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Scene file format

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Contents

Introduction

In order to pass scene data for rendering, either the luxrender API or the .lxs file format can be used. While the API and the .lxs file format are closely related, this document only covers the description of the .lxs file format. This should aid both exporter writers and those wishing to gain more control over the rendering process.

Basics

An .lxs file is an ASCII text file with a full description of the scene to be rendered. As scene descriptions can get quite large, there is a mechanism to break the scene description down into more manageable pieces: the description can be spread over several text files. The suggested organization is the following:

  1. A main scene file with extension '.lxs'. For example: 'scene.lxs'
  2. An included Material file with suffif '-mat' and extension '.lxm'. For example: 'scene-mat.lxm'
  3. An included Geometry file with suffix '-geom' and extension '.lxo'. For example: 'scene-geom.lxo'
  4. An optional Volume file with suffix '-vol' and extension '.lxv'. For example: 'scene-vol.lxv'

You can include each additional file into the scene file via the "Include" statement:

Include "scene-geom.lxo"

Coordinate System

LuxRender uses a 3D coordinate system where the Z axis points upward and where positive increments of the Y coordinate move away from the camera. This is consistent with Blender's coordinate system. If you need to write an exporter from a program that uses a Y-up system, you need to swap the Y value with the Z value when writing the LuxRender file. In addition, if positive values of the original Z axis move the object toward the camera, you will need to multiply that value by -1 when exporting to Lux.

Basic Structure

While the contents of .lxs files may vary considerably, even the simplest scenes will have the following: a camera specification, at least one light source, a film specification, transformations, primitives, materials, textures and so on...

The following example .lxs file will be the example used in all following explanation:

#This is an example of a comment!
#Global Information
LookAt 0 10 100 0 -1 0 0 1 0
Camera "perspective" "float fov" [30]

Film "fleximage"
"integer xresolution" [200] "integer yresolution" [200]

PixelFilter "mitchell" "float xwidth" [2] "float ywidth" [2]

Sampler "lowdiscrepancy" "string pixelsampler" ["lowdiscrepancy"]

#Scene Specific Information
WorldBegin

AttributeBegin
	CoordSysTransform "camera"
	LightSource "distant"
		"point from" [0 0 0] "point to" [0 0 1]
		"color L" [3 3 3]
AttributeEnd

AttributeBegin
	Rotate 135 1 0 0

	Texture "checks" "color" "checkerboard"
		"float uscale" [4] "float vscale" [4]
		"color tex1" [1 0 0] "color tex2" [0 0 1]

	Material "matte"
		"texture Kd" "checks"
	Shape "disk" "float radius" [20] "float height" [-1]
AttributeEnd

WorldEnd

Global vs Scene Specific Information

Notice that in the .lxs file structure, global information is given before scene specific information.

Global information

This is information that describes how the scene is going to be rendered; it includes types of and settings for the camera, sampler and film and so on. While the position and rotation of a camera may be considered part of the specific scene description, the camera defines the final render area and is therefore more important to the rendering process than say, geometry. This data is given at the top of the .lxs file.

LookAt

The Lookat transformation takes 3 vectors as options:

LookAt0 0 0
0 0 0
0 0 0

The first vector (0 0 0 in my example) is the position of the camera.
The second vector (0 1 0) is the position of the target of the camera.
The last vector (0 0 1) is the up vector.

This is quite a simple transformation, which allows you to specify 2 points, one where the camera is located and another point of 'interest'. This can also be given as a unit vector. The up vector is a unit vector which defines how the camera is help up, it should point upwards of your camera, eg if it is held straight, it will be 0 0 1 (+Z up)

Scene specific information

Geometry, materials, textures - these obviously affect the final image but have no bearing on how the scene is to be rendered. This data is given between the WorldBegin and WorldEnd statements after the global information. More on these statements and the 'Attribute' statements a little later.

The distinction between the global information and the scene specific information is not arbitrary. LuxRender processes and "locks" global information first before looking at scene specific information. This implementation would allow you to tessellate geometry based on what is viewed from the camera, for instance.

Components of a .lxs file

Notice these features occur frequently throughout the .lxs file:

  • Comments

Any text on a line beginning with a # is ignored by the parser. Often these are useful to give readable descriptions of what you are doing!

  • Statements

'WorldBegin' and 'AttributeEnd' are examples of statements. These are important in describing the properties of whole blocks of data.

  • Identifiers

'Camera', 'Sampler', 'Texture' and 'Material' are some examples of identifiers. These indicate what aspect of the scene is being described.

  • Types

These are given in quotes, often after an identifier to specify an implementation to use. For example, by giving the type "perspective" after the 'Camera' identifier, the renderer can use the intended camera model.

  • Parameters

Parameters typically consist of two parts: the type of parameter followed by the parameter name in given in quotes, followed by the actual value of the parameter given. The type of a parameter can be an integer, a float, a point, a normal, a color, a bool or a string. Continuing our example, the field of view ('fov') needs to be passed to our camera and as this parameter is of type float, we type "float fov" [30]. Note that as 'Rotate' and 'LookAt' take a predetermined amount of numbers and types of arguments they do not need parameter types or quotes.

Importance of parameter types

It is important to explain why you need to specify whether you are giving an integer or float every single time you give a parameter. It may seem like that tedium should be taken care of automatically, but LuxRender would be far less flexible if that were the case. LuxRender is based on plugins, functional sections of code that the core renderer does not need to know anything about. By specifying the parameter type, LuxRender can handle new plugins in a uniform way, allowing developers to realise new features quicker. To reiterate, the parameter types are:

Type Description Example
integer     a whole number 1, 2, 3 ...
float a number with a decimal point [1.67], [2.54] ...
Note the square brackets given around the values.
point declares a point, given by three floating point values [45.000 12.000 0.900]
vector a vector, specified the same way as a point. [12.000 3.120 1.100]
normal a normal (unit vector) same as a point.
color RGB color [r g b] expressed in decimal notation ([0.123 1.0 0.245])
bool Boolean ["true"] , ["false"]
string string, non-escaped, surrounded by quotes "simple.exr", "lux.png".

Arrays are created by specifying more than one value inside brackets, separated by space. So a point or a vector is actually an array of floats. In this tutorial we will indicate this by using [n] after the type name, where n is the number of elements required. For example, a valid float[4] would be [0 1 2 3].

Transformations

Any number of transformation can be applied to a section of the scene. To make the transformation "local" it's advisable to enclose them between "TransformBegin" and "TransformEnd". These two commands define a block that is then removed when the TransformEnd command is reached. From that point on, the previously defined, possibly global, transformations will be restored. For example:

TransformBegin
  Rotate 90 0 1 0

  Shape "cone"
TransformEnd

The following transformation commands are available:

Command Description Example
Rotate Rotates an entity by a given number of degrees around a given axis.
The first parameter is the rotation in degrees, the following parameters indicate the X, Y and Z axis.
A 0 means to leave the axis unaffected, a 1 means to rotate on that axis.
Rotate 180 1 0 0
Rotates the object around the X-axis 180°
Scale Adjusts the size of an entity by a given factor.

Scale .1 .2 .3
Scales in the X-direction to 10%, the Y-direction to 20%, and the Z-direction to 30%

Translate Moves an entity in a given direction by a vector. Translate 10.1 20.2 30.3
Moves the center 10.1 units in the X-direction, 20.2 in the Y-direction, and 30.3 in the Z-direction

Alternatively you can use a transformation matrix within an Attribute or Object block:

Transform [scale_x 0.0 0.0 0.0 0.0 scale_y 0.0 0.0 0.0 0.0 scale_z 0.0 move_x move_y move_z 1.0]

When a Transform statement is used in conjunction with an ObjectInstance statement, the transform will be applied relative to the source object. For example, the following scene snippet adds an instance of a previosuly defined object called cube_1 by applying some transformation:

TransformBegin
Transform [
0.104530  0.232589  0.124276  0.000000
-0.263707  0.091819  0.049964  0.000000
0.000741  -0.133942  0.250055  0.000000
0.325424  -0.962074  0.479735  1.000000
]
ObjectInstance "cube_1"
TransformEnd

The transform is not applied in World Coordinates, instead it is relative to the transforms of cube_1. If an exporter needs to obtain the relative matrix, the following formula, in pseudo-code, can be used:

Matrix m1 = sourceObject.getWorldSpaceMatrix()
Matrix m2 = instanceObject.getWorldSpaceMatrix()
  
Matrix luxTransform = m1.inverse() * m2

Attributes

  • WorldBegin

The WorldBegin attribute indicates the end of the global information and the beginning of the scene specific information.

  • WorldEnd

The WorldEnd attribute indicates the end of the scene specific information and marks the end of the file (if no comments follow).

  • AttributeBegin

The AttributeBegin attribute indicates the beginning of the description of an unnamed object. In case the object needs to be referenced (for example by instances), use ObjectBegin instead.

  • AttributeEnd

AttributeEnd marks the end of the description of an unnamed object.

  • ObjectBegin

The ObjectBegin attribute indicates the beginning of the description of a named object, which is useful for creating instances. It must be followed by a string, indicating the name of the object.

  • ObjectEnd

ObjectEnd marks the end of the description of a named object.

  • ObjectInstance

If a named object is created, it can be referenced in multiple objects. These objects can be ordinary unnamed objects that use an ObjectInstance line instead of a shape definition. It must be followed by a string with the name of the object to instance.

Identifiers

The following identifiers can be included in the scene:

  • Camera
  • Sampler
  • Film
  • PixelFilter
  • Shape
  • Accelerator
  • Material
  • Texture
  • Volume
  • Light
  • SurfaceIntegrator
  • VolumeIntegrator

Each of these shall be covered in turn.

Camera

The following camera types are available. Each of them is a plugin. The default camera type is 'perspective'.

  • perspective (default)

The most common camera, resemble most closely what is seen by the human eye or a pinhole camera.

  • environment

Denotes a type of camera which maps the whole of the environment around the camera to an image.

  • orthographic

The standard orthographic camera: parallel lines stay parallel and a sense of depth is lost.

  • realistic

A physically-based camera model that loads lens descriptions files to realistically generate camera rays and weights.

Common Camera Parameters

There are parameters specific to a particular camera implementation and general parameters for all cameras. Here are the common parameters:

name type description default value theoretical range suggested range
hither float Geometry closer than this distance will not be rendered 10 − 3 0 - ∞ 0 - 10 000
yon float Geometry further than this distance will not be rendered 1030 0 - ∞ 0 - 10 000 (always bigger than hither)
shutteropen float The time in seconds at which the virtual shutter opens 0.0 0 - 1
shutterclose float The time in seconds at which the virtual shutter closes 1.0 0 - 1
lensradius float Default (0) for pinhole camera with whole scene in focus, increase for depth of field and focus effects. Ignored by environment and realistic cameras 0.0 0 - ∞ 0 - 1
focaldistance float Focal distance of the virtual lens. Use the control focus in depth of field effects. Ignored by environment and realistic cameras 1030 0 - ∞ 0 - 10 000
frameaspectratio float This is normally computed from resolution but can be overridden here. Ignored by realistic camera computed from given resolution 0 - ∞ 1 - 10
screenwindow float[4] Specifies area in camera that the virtual film occupies - the bounds in screen space. Crops the camera viewport. (Ignored by realistic camera.) Values are: xmin xmax ymin ymax. entire screen space dependent on frame aspect ratio (xresolution/yresolution):
If aspect_ratio > 1: -aspect_ratio aspect_ratio -1 1
Otherwise: -1 1 -1/aspect_ratio 1/aspect_ratio

Specific Camera Parameters

'environment' cameras do *not* support depth of field parameters lensradius and focaldistance as indicated above. 'realistic' cameras don't support lensradius, focaldistance, frameaspectratio and screenwindow either. However, the 'perspective' and 'realistic' cameras do have some specific parameters:

perspective

name type description default value theoretical range suggested range
fov float This is the field of view for the camera - this specifies the solid angle viewed. The fov value is the angle spanned by the smallest dimension of the image (width/height). An fov of 49.13 is equal to a focal length of 35mm. 90 0 < x < 180 1 - 179
lensradius float This value defines the lens radius. Values higher than 0 enable DOF and control its amount. To calculate the lensradius based on the f/stop number use the following equation.

lensradius = (focallength_in_mm / 1000.0) / ( 2.0 * fstop )

Example: 0.00625 = (35 / 1 000.0) / (2.0 * 2.8)

0.00625 x ≥ 0 0 - 0.4
autofocus bool Enable/disable the autofocus feature. It is useful to automatically calculate the focal distance when lens radius > 0.0 (i.e. depth of field enabled). false
focaldistance float This value controls the focal point of the scene, the distance from the camera at which objects will be in focus. It has no effect if the Lens Radius is set to 0. It is specified in meters. This value is not needed when using autofocus. 0.0 0 < x 0 - 200
blades integer This value controls the number of blade edges of the aperture, values 0 to 2 defaults to a circle. 6
distribution string This value controls the lens sampling distribution. Non-uniform distributions allow for ring effects. Valid values include: "uniform", "exponential", "inverse exponential", "gaussian", and "inverse gaussian". uniform
power integer This value controls the exponent for the expression in exponential distribution. Higher values gives a more pronounced ring effect. 1

realistic

This camera type is not currently functional and should thus not be present in the user interface.

name type description default value
specfile string The .dat lens specification file which can be found in the cameras/realistic directory ""
filmdistance float Distance from the film to the backmost lens component (milimeters) 70.0
aperture_diameter float The aperture diameter of the aperture stop 1.0
filmdiag float Film diagonal size 35.0

Sampler

Here are the sampler types. Each one is a separate plugin.

  • random (default)

Completely random sampler

  • lowdiscrepancy

Generates a low discrepancy sequence that evenly samples values, given a target number of samples per pixel

  • metropolis

Generates random values that are then slightly mutated, according to the Metropolis algorithm

  • erpt

Similar to the Metropolis sampler but the Energy Redistribution Path Tracing algorithm is used

Samplers Parameters

These samplers accept the parameters below. Valid values for pixelsampler are hilbert (since v0.6), linear, vegas, lowdiscrepancy, tile (or alias grid), and random.

NOTE: grid pixel sampler is mainly intended for long run rendering with Network rendering. It is quite important to use this kind of pixel sampler in order to improve the cache coherency and to reduce the network bandwidth usage.

random

name type description default value theoretical range suggested range
pixelsamples integer Number of samples per pixel / pass 4 x ≥ 1 1 - 512
pixelsampler string Pixel sampler algorithm to use: hilbert, linear, vegas, lowdiscrepancy, tile (or alias grid) or random vegas

lowdiscrepancy

name type description default value theoretical range suggested range
pixelsamples integer Number of samples per pixel / pass 4 x ≥ 1 1 - 512
pixelsampler string Pixel sampler algorithm to use: hilbert, linear, vegas, lowdiscrepancy, tile (or alias grid) or random vegas

metropolis

name type description default value theoretical range recommended range
maxconsecrejects integer Number of consecutive rejects before a next mutation is forced. Low values can cause bias 512 x ≥ 0 0 - 32768
largemutationprob float Probability of generating a large sample mutation 0.4 0 ≤ x ≤ 1 0 - 1
mutationrange float Maximum distance in pixel for a small mutation \frac{(render_{width} + render_{height})}{32.}
usevariance bool Use the variance hint provided by some integrators to alter sample acceptance false

erpt

name type description default value theoretical range recommended range
initsamples integer Number of warm-up samples 100000
chainlength integer Number of mutations from a given seed 2000 x ≥ 1 1 - 32768
mutationrange float Maximum distance in pixel for a small mutation \frac{(render_{width} + render_{height})}{50.}

Film

There is currently only one film type:

  • fleximage (default)

A flexible film, being able to output several buffers, with some image normalization options.

Specific Film Parameters

fleximage

name type description default value theoretical range recommended range
xresolution integer The number of pixels in the xdirection 800 x ≥ 1 1 - 10000
yresolution integer The number of pixels in the ydirection 600 x ≥ 1 1 - 10000
cropwindow float[4] Values describing render region that range from min (0) to max (1) in order xmin, xmax, ymin,ymax. (0,0) is top left (0,1,0,1) all values: 0 ≤ x ≤ 1
gamma float Gamma correction value 2.2 x ≥ 0 0 ≤ x ≤ 5
premultiplyalpha bool Multiplies the pixel colours by the pixel's alpha value before writing the image. Used to encode alpha in images without an alpha channel false
colorspace_red float[2] The xy chromaticity coordinates of the red primary in the target color space. Used for low dynamic range output (and OpenEXR if write_exr_applyimaging is enabled). Default color space is SMPTE. [0.63 0.34]
colorspace_green float[2] Same as colorspace_red but for the green primary. [0.31 0.595] both values: 0 ≤ x ≤ 1 both values: 0 ≤ x ≤ 1
colorspace_blue float[2] Same as colorspace_red but for the blue primary. [0.155 0.07] both values: 0 ≤ x ≤ 1 both values: 0 ≤ x ≤ 1
colorspace_white float[2] Same as colorspace_red but for the white point. [0.314275 0.329411] both values: 0 ≤ x ≤ 1 both values: 0 ≤ x ≤ 1
write_exr bool Toggles the .exr (OpenEXR) output false
write_exr_channels string Which channels to write for OpenEXR output. Valid values are "RGB", "RGBA", "Y" and "YA". "RGBA" is RGB with alpha, "Y" is luminosity, and "YA" is luminosity with alpha. "RGB"
write_exr_halftype bool Indicates if the half-float (16bit) type should be used for OpenEXR output. true
write_exr_compressiontype string Which compression scheme to use for OpenEXR output. Valid values are "RLE (lossless)", "PIZ (lossless)", "ZIP (lossless)", "Pxr24 (lossy)" and "None". "PIZ (lossless)"
write_exr_applyimaging bool Specifies if the imaging pipeline (for tone mapping, bloom etc) should be used for OpenEXR output. Use "false" to get the raw HDR output. "true"
write_exr_gamutclamp bool Specifies if out-of-gamut colors should be clamped for OpenEXR output. "true"
write_exr_ZBuf bool Specifies if the Z-Buffer should be used for OpenEXR output. Will be added as a separate channel in the OpenEXR file. "false"
write_exr_zbuf_normalizationtype string Specifies which normalization, if any, is applied to the Z-Buffer before being added to the OpenEXR file. Valid values are "Camera Start/End clip", "Min/Max" and "None". "None"
write_png bool Toggles the .png low dynamic range tonemapped output. true
write_png_channels string Same as write_exr_channels, but for PNG output. "RGB"
write_png_16bit bool Toggles 16 bit per channel PNG output. false
write_png_gamutclamp bool Toggles clamping of out-of-gamut colors for PNG output. true
write_tga bool Toggles the .tga low dynamic range tonemapped output false
write_tga_channels string Same as write_exr_channels, but for TGA output. "RGB"
write_tga_gamutclamp bool Toggles clamping of out-of-gamut colors for TGA output. true
write_tga_zbuf_normalization string TBD N/A
ldr_clamp_method string Method used to clamp out-of-gammut colors after tonemapping. Valid values are "lum", "hue" and "cut". First two tries to preserve luminosity and hue, respectively, of the color. "cut" will simply clip large values. "lum"
write_resume_flm bool Toggles the rendering resume output. Luxrender will auto-resume a rendering if the resume file exists. (NOTE1: the resume feature doesn't include any sanity check, do not forget to erase the file if you are starting a new rendering or you have modified the scene description. NOTE2: the resume file is usually read between 10-30 secs after the start of the rendering. NOTE3: this feature works well only with progrsive pixel samplers.) false
restart_resume_flm bool Disables starting from an existing flm file, whilst still writing a new one if above param is true. false
filename string The suffix used for all file output "luxout"
writeinterval integer The interval in seconds between all image writes 60 x ≥ 1 1 - 36000
displayinterval integer The interval in seconds between display updates 12 x ≥ 1 1 - 36000
reject_warmup integer The minimum number of samples per pixel before rejecting samples 12 x ≥ 0 1 - 50000
haltspp integer Stop the rendering when the average number of samples per pixel is higher or equal to the chosen value. The rendering will stop at the next valid Sampler/PixelSampler state in order to not introduce bias (i.e. few more samples can be required to reach that state). A value less or equal to 0 disables this option. 0 x ≥ 0 0 - 50000
halttime integer Stop the rendering when the time elapsed form the start is higher or equal to the chosen value (defined in seconds). The rendering will stop at the next valid Sampler/PixelSampler state in order to not introduce bias (i.e. few more samples can be required to reach that state). A value less or equal to 0 disables this option. 0 x ≥ 0 0 - 86400
tonemapkernel string The tone mapping kernel used for low dynamic range output (and OpenEXR if write_exr_applyimaging is

enabled). Valid values are "reinhard", "linear", "contrast" and "maxwhite".

"reinhard"

Tonemapper Parameters

Fleximage accepts the following parameters for the various tone mapping kernels:

reinhard

name type description default value theoretical range recommended range
reinhard_prescale float Defines the amount of pre-scale 1.0 x ≥ 0 0 - 8
reinhard_postscale float Defines the amount of post-scale 1.0 x ≥ 0 0 - 8
reinhard_burn float Defines the amount of burn 6.0 x ≥ 0 0 - 8

linear

name type description default value theoretical range recommended range
linear_sensitivity float Sensitivity of the film (in ISO). 50.0 x ≥ 0 6 - 6400
linear_exposure float Exposure time of the film in seconds (currently not tied to shutter opening). 1.0 x > 0 0.0005 - 60
linear_fstop float F-stop value. 2.8 x ≥ 0 0.7 - 96
linear_gamma float Gamma value (separate from the FlexImageFilm's gamma parameter). 1.0 x ≥ 0 0 - 5

contrast

name type description default value theoretical value recommended value
contrast_ywa float Ywa parameter for the contrast tone mapping kernel. 1.0 x > 0 0 - 20000

maxwhite

The maxwhite kernel has no parameters.

Filter

Here are the pixel filter types. Each one is a separate plugin:

  • box
  • triangle
  • gaussian
  • mitchell (default)
  • sinc

Filter Parameters

box

name type description default value theoretical range recommended range
xwidth float Half-width (or radius) of the filter in the x direction 0.5 x > 0 0.1 - 2
ywidth float Half-width (or radius) of the filter in the y direction 0.5 x > 0 0.1 - 2

triangle

name type description default value theoretical range recommended range
xwidth float Half-width (or radius) of the filter in the x direction 2 x > 0 0.1 - 2
ywidth float Half-width (or radius) of the filter in the y direction 2 x > 0 0.1 - 2

gaussian

name type description default value theoretical range recommended range
xwidth float Half-width (or radius) of the filter in the x direction 2 x > 0 0.1 - 2
ywidth float Half-width (or radius) of the filter in the y direction 2 x > 0 0.1 - 2
alpha float Gaussian rate of falloff. Lower values give blurrier images. 2 x > 0 0 - 10

mitchell

name type description default value theoretical range recommended range
xwidth float Half-width (or radius) of the filter in the x direction 2 x > 0 0.1 - 3
ywidth float Half-width (or radius) of the filter in the y direction 2 x > 0 0.1 - 3
B float B parameter for the mitchell filter in the range 1/3 0 ≤ x ≤ 1 0 - 1
C float C parameter for the mitchell filter in the range 0..1. 1/3 0 ≤ x ≤ 1 0 - 1

sinc

name type description default value theoretical range recommended range
xwidth float Half-width (or radius) of the filter in the x direction 4 x > 0 0.1 - 5
ywidth float Half-width (or radius) of the filter in the y direction 4 x > 0 0.1 - 5
tau float Width of the filter window. Should not be larger than the radius of the filter. 3 x > 0 0.1 - 5

Shape

Here are the shape types. Each one is a separate plugin.

  • cone
  • cylinder
  • disk
  • heightfield
  • hyperboloid
  • lenscomponent
  • loopsubdiv
  • nurbs
  • paraboloid
  • plymesh
  • sphere
  • trianglemesh
  • mesh

Specific Shape Parameters

These parameters are specific to individual shape plugins. There are no common parameters.

Cone

name type description default value
cone::radius float The radius of the cone. 1.0
cone::radius2 float The radius of the cone upper face in case of a cone frustum (available since v0.7). 0.0
cone::height float The height of the cone - along the z axis 1.0
cone::phimax float The angle (degrees) swept out by the cone round its circular base 360.0

Cylinder

name type description default value
cylinder::radius float The radius of the cylinder 1.0
cylinder::zmin float The position of the bottom of the cylinder along the z axis -1.0
cylinder::zmax float The position of the top of the cylinder along the z axis 1.0
cylinder::phimax float The angle (in degrees) swept out by the cylinder 360.0

Disk

name type description default value
disk::height float The location of the disk (which is flat) along the z-axis 0.0
disk::radius float The radius to the outer rim of the disk 1.0
disk::innerradius float The radius to the inner rim of the disk - defines a "hole" in the disk 0.0
disk::phimax float The angle (degrees) swept out by the disk 360.0

Height Field

name type description default value
heightfield::nu integer Number of points in the u axis none - must be specified
heightfield::nv integer Number of points in the v axis none - must be specified
heightfield::Pz float[nu*nv] The height of each point in the grid none - must be specified

Hyperboloid

name type description default value
hyperboloid::p1 point The hyperboloid lies between p1 and p2. Here p1 defines the start of the hyperboloid 0 0 0
hyperboloid::p2 point The hyperboloid lies between p1 and p2. Here p2 defines the end of the hyperboloid 0 0 0
hyperboloid::phi float The angle (in degrees) swept out by the hyperboloid 360.0

Subdivision Surfaces

name type description default value
loopsubdiv::nlevels integer The level of subdivision applied to the base mesh 3
loopsubdiv::indices integer[n] Indices of the cage mesh - using the same format as used in the triangle primitive none - must be specified
loopsubdiv::P point[n] Vertex positions of the cage mesh - using the same format as used in the triangle primitive none - must be specified
loopsubdiv::uv float[2*n] Vertex texture coordinates of the cage mesh - using the same format as used in the triangle primitive none - optional
loopsubdiv::displacementmap string The name of a float texture to use as displacement map none - optional
loopsubdiv::dmscale float Scale the output of displacement map by the specified value (use negative value in order to invert the map) 0.1
loopsubdiv::dmoffset float Translate the output of displacement map by the specified value 0.0
loopsubdiv::dmnormalsmooth bool Interpolate normals in order to get a smooth output true
loopsubdiv::dmsharpboundary bool The output mesh will have the same boundary of the cage mesh if this flag is true, otherwise the boundary will be interpolated as well false

Lens Component

This shape is primarily used by the realistic camera. Lens are approximated by a sphere section.

name type description default value
lenscomponent::radius float The radius of the sphere 1.0
lenscomponent::zmin float The position of the bottom of the sphere along the z axis -radius
lenscomponent::zmax float The position of the top of the sphere along the z axis radius
lenscomponent::phimax float The angle (in degrees) swept out by the sphere 360.0
lenscomponent::aperture float The aperture of the lens 1.0

NURBS

name type description default value
nurbs::nu integer Sets the number of control points in the u direction none - must be specified
nurbs::nv integer Sets the number of control points in the v direction none - must be specified
nurbs::uorder integer The order (surface degree + 1) in the u direction Defines how many nearby control points affect each control point none - must be specified
nurbs::vorder integer The order (surface degree + 1) in the v direction. Defines how many nearby control points affect each control point none - must be specified
nurbs::uknots float[nu+uorder] (eg. if nu = 2 and uorder = 2 we have a float[4] such as (1,1,1,1)) The knot vector in the u direction none - must be specified
nurbs::vknots float[nv+vorder] The knot vector in the v direction none - must be specified
nurbs::u0/nurbs::v0 float The u and v coordinates from which NURB surface evaluation starts uknots[uorder-1]/vknots[vorder-1]
nurbs::u1/nurbs::v1 float The u and v coordinates from which NURB surface evaluation ends uknots[nu]/vknots[nv]
nurbs::P point[nu*nv] P specifies regular control points on the NURBS surface none - one of either P or Pw must be specified
nurbs::Pw float[4*nu*nv] Pw specifies rational control points on the surface which include a weight value for each control point none - one of either P or Pw must be specified

Paraboloid

name type description default value
paraboloid::radius float The radius of the paraboloid 1.0
paraboloid::zmin float The position of the bottom the paraboloid along the z axis 0.0
paraboloid::zmax float The position of the top the paraboloid along the z axis 1.0
paraboloid::phimax float The angle (in degrees) swept out by the paraboloid 360.0

PLY Mesh Loader

name type description default value
plymesh::filename string The .ply filename to load none
plymesh::smooth bool Toggles smoothing of the mesh faces false

Plymesh example:

AttributeBegin # Plymodel
     NamedMaterial "plymodel"
     Shape "plymesh"
     "string filename" ["c:\\blender\\models\\plymesh.ply"]
AttributeEnd

Sphere

name type description default value
sphere::radius float The radius of the sphere 1.0
sphere::zmin float The position of the bottom of the sphere along the z axis Set to - sphere::radius
sphere::zmax float The position of the top of the sphere along the z axis Set to - sphere::radius
sphere::phimax float The angle (in degrees) swept out by the sphere 360.0

Triangle Mesh

There are two types of triangle mesh: barytrianglemesh and waldtrianglemesh. Both have the same below parameters but waldtrianglemesh uses a better intersection algorithm. Using only trianglemesh defaults to the barytrianglemesh which is better tested.

name type description default value
trianglemesh::indices integer[n] An array indexing the triangles found in the P array. The three vertices of the ith triangle are given by 3i, 3i+1, 3i+2. This provides the ordering of the triangles none - must be specified
trianglemesh::P point[n] An unordered list of vertex positions in the triangle mesh. Ordered with trianglemesh::indices none - must be specified
trianglemesh::N normal[n] Per vertex normals over the triangle mesh none - optional
trianglemesh::S vector[n] Tangents given at each vertex. Tangents are perpendicular to normals none - optional (deprecated)
trianglemesh::uv float[2*n] Texture coordinates (per vertex) none - optional
trianglemesh::st float[2*n] Texture coordinates (per vertex) none - optional

Mesh

Available since v0.6.

name type description default value
mesh::N normal[n] Per vertex normals over the mesh none - optional
mesh::P point[n] An unordered list of vertex positions in the mesh. none - must be specified
mesh::acceltype string Accelerator structure to use (auto, bruteforce, grid, kdtree, none, qbvh) "auto"
mesh::displacementmap string Name of the texture used for the displacement none - optional
mesh::dmscale float Scale of the displacement (for an LDR map, this is the maximum height of the displacement in meter) 0.1
mesh::dmoffset float Offset of the displacement 0
mesh::dmnormalsmooth bool Smoothing of the normals of the subdivided faces true
mesh::dmsharpboundary bool Try to preserve mesh boundaries during subdivision false
mesh::nsubdivlevels integer Number of subdivision levels 0
mesh::quadindices integer[4*q] An array indexing the quadrilaterals found in the P array. The three vertices of the ith quadrilateral are given by 4i, 4i+1, 4i+2, 4i+3. This provides the ordering of the quadrilaterals none - must be specified
mesh::quadtype string Select the intersection routine used for quadrilaterals (quadrilateral) "quadrilateral"
mesh::subdivscheme string Subdivision algorithm (loop) "loop"
mesh::triindices integer[3*t] An array indexing the triangles found in the P array. The three vertices of the ith triangle are given by 3i, 3i+1, 3i+2. This provides the ordering of the triangles none - must be specified
mesh::tritype string Select the intersection routine used for triangles (auto, bary, wald) "auto"
mesh::uv float[2*n] Texture coordinates (per vertex) none - optional

Accelerators

Here are the accelerator types. Each one is a separate plugin.

  • tabreckdtree or kdtree (default)
  • unsafekdtree
  • qbvh
  • sqbvh
  • none

Specific Accelerator Parameters

These parameters are specific to individual accelerator plugins. There are no common parameters:

Kdtree

name type description default value
kdtree::intersectcost integer Parameter that specifies how computationally expensive ray-object intersections are expected to be. This is used to control the kdtree built. 80
kdtree::traversalcost integer Computational cost expected for traversing a ray through the kdtree 1
kdtree::emptybonus float Promotes kd-tree nodes that represent empty space. 0.5
kdtree::maxprims integer Maximum number of primitives in a kdtree volume before further splitting of the volume occurs. 1
kdtree::maxdepth integer If positive, the maximum depth of the tree. If negative this value is set automatically. -1

Unsafe Kdtree

This accelerator is not thread-safe and so its use should be avoided.

name type description default value
unsafekdtree::intersectcost integer Parameter that specifies how computationally expensive ray-object intersections are expected to be. This is used to control the kdtree built. 80
unsafekdtree::traversalcost integer Computational cost expected for traversing a ray through the kdtree 1
unsafekdtree::emptybonus float Promotes kd-tree nodes that represent empty space. 0.5
unsafekdtree::maxprims integer Maximum number of primitives in a kdtree volume before further splitting of the volume occurs. 1
unsafekdtree::maxdepth integer If positive, the maximum depth of the tree. If negative this value is set automatically. -1

QBVH

This accelerator is a variant of the BVH accelerator that has 4 children per node instead of two and uses SSE instructions to traverse the tree. It uses much less memory than kd-tree while providing an equivalent speed.

name type description default value
qbvh::maxprimsperleaf integer The maximum number of primitives in a tree node 4
qbvh::fullsweepthreshold integer The number of primitives that triggers partial scanning to determine the splitting plane 4 * maxprimsperleaf
qbvh::skipfactor integer How many primitives will be grouped together when partial scanning is done to determine the split plane 1

SQBVH

Varient of the QBVH accelerator that uses spatial-splits. This accelerator can be faster than the normal QBVH, but may use more memory and take longer to build.

name type description default value
qbvh::maxprimsperleaf integer The maximum number of primitives in a tree node 4
qbvh::fullsweepthreshold integer The number of primitives that triggers partial scanning to determine the splitting plane 4 * maxprimsperleaf
qbvh::skipfactor integer How many primitives will be grouped together when partial scanning is done to determine the split plane 1

Materials

Here are the material types. Each one is a separate plugin.

  • carpaint
  • glass
  • glossy
  • matte (default)
  • mattetranslucent
  • metal
  • mirror
  • mix
  • null
  • roughglass
  • shinymetal

Common Material Parameters

Here are the common parameters for materials. Note that float and color textures are described in the 'Texture' section.

name type description default value
bumpmap float texture The floating-point texture for use as a bump map None

Integrator Dependant Parameters

The following material parameters are available on all materials for the stated Integrators:

name type integrator description default value
compo_visible_material bool distributedpath XXX true
compo_visible_emission bool distributedpath XXX true
compo_visible_indirect_material bool distributedpath XXX true
compo_visible_indirect_emission bool distributedpath XXX true
compo_override_alpha bool distributedpath Override the alpha value in the output image for hits on this material false
compo_override_alpha_value float distributedpath Value to set alpha to when overridden 0.0

Specific Material Parameters

These parameters are specific to individual material plugins.

Car Paint

The available names for the carpaint material are:

  • "ford f8"
  • "polaris silber"
  • "opel titan"
  • "bmw339"
  • "2k acrylack"
  • "white"
  • "blue"
  • "blue matte"

Other parameters are only necessary if no name given.

name type description default value
carpaint::name string The name of the car paint model to use "ford f8"
carpaint::Kd spectrum texture Diffuse component "ford f8" data
carpaint::Ks1 / carpaint::Ks2 / carpaint::Ks3 spectrum texture Specular component of layers "ford f8" data
carpaint::R1 / carpaint::R2 / carpaint::R3 float texture Fresnel constants of layers "ford f8" data
carpaint::M1 / carpaint::M2 / carpaint::M3 float texture Microfacet roughness of layers "ford f8" data

Glass

name type description default value
glass::Kr color, texture The reflectivity of the surface [1.0 1.0 1.0]
glass::Kt color, texture Fraction of light transmitted through the surface [1.0 1.0 1.0]
glass::index float, texture The index of refraction for the glass surface 1.5
glass::cauchyb float, texture Cauchy B coefficient 0.0
glass::film float, texture The thickness in nanometers of the thin film coating (0.0 disables) on the surface 0.0
glass::filmindex float, texture The index of refraction of the thin film coating on the surface 1.5

Glossy

name type description default value
glossy::Kd color texture The coefficient of diffuse reflection 0.5
glossy::Ks color texture The coefficient of specular reflection 0.5
glossy::Ka color texture The coefficient of absorption of the coating layer 0.0
glossy::uroughness float texture The roughness of the surface in the u direction 0.1
glossy::vroughness float texture The roughness of the surface in the v direction 0.1
glossy::d float texture The depth (thickness) of the coating layer for absorption effects. (0 = disables) 0.0
glossy::index float texture IOR of the coating. 0.0

Matte

name type description default value
matte::Kd color texture The diffuse reflectivity of the surface 1.0
matte::sigma float texture The sigma parameter in the Oren-Nayer shader in degrees. Zero for pure Lambertian reflection 0.0

MatteTranslucent

name type description range default value
matte::Kr color texture The diffuse reflectivity of the surface 1.0
matte::Kt color texture The diffuse transmitivity of the surface 1.0
matte::sigma float texture The sigma parameter in the Oren-Nayer shader in degrees. Zero for pure Lambertian reflection 0.0 - 90.0 0.0

Metal

These are the possible inbuilt metal names:

  • "amorphous carbon"
  • "silver"
  • "gold"
  • "copper"
  • "aluminium"
name type description default value
metal::name string The name of the desired inbuilt metal or nkdata file. 1.0
metal::uroughness float texture Roughness of the surface in the u direction from 0 to 1. Rough surfaces have blurry highlights 0.001
metal::vroughness float texture Roughness of the surface in the v direction from 0 to 1. Rough surfaces have blurry highlights 0.001

Mirror

name type description default value
mirror::Kr color texture The reflectivity of the mirror 1.0
glass::film float texture The thickness in nanometers of the thin film coating (0.0 disables) on the surface 0.0
glass::filmindex float texture The index of refraction of the thin film coating on the surface 1.5

Mix

name type description default value
mix::namedmaterial1 string The name of the first material to mix None
mix::namedmaterial1 string The name of the second material to mix None
mix::amount float texture The value or texture to mix by 0.5

Null

The Null material takes no options.

Rough Glass

name type description default value
roughglass::Kr color texture The reflectivity of the surface 1.0
roughglass::Kt color texture Fraction of light transmitted through the surface 1.0
roughglass::uroughness float texture Roughness of the surface in the u direction from 0 to 1. Rough surfaces have blurry highlights 0.001
roughglass::vroughness float texture Roughness of the surface in the v direction from 0 to 1. Rough surfaces have blurry highlights 0.001
roughglass::index float texture The index of refraction for the glass surface 1.5
roughglass::cauchyb float texture Cauchy B coefficient 0.0

Shiny Metal

name type description default value
roughglass::uroughness float texture Roughness of the surface in the u direction from 0 to 1. Rough surfaces have blurry highlights 0.001
roughglass::vroughness float texture Roughness of the surface in the v direction from 0 to 1. Rough surfaces have blurry highlights 0.001
shinymetal::Ks color texture The coefficient of glossy reflection 1.0
shinymetal::Kr color texture The coefficient of specular reflection 1.0
glass::film float texture The thickness in nanometers of the thin film coating (0.0 disables) on the surface 0.0
glass::filmindex float texture The index of refraction of the thin film coating on the surface 1.5

Texture

General Syntax

Texture NAME color|float|spectrum TYPE <values>

Where NAME is a quoted string, and TYPE is one of the types listed below. The second parameter for a texture denotes if this texture defines values of type color, float or spectrum.


Textures are declared differently from what we have seen so far. An example of a texture declaration is:

Texture "checks" "color" "checkerboard"

'checks' is the name given by the user to the texture. This name is arbitrarily chosen by the user to refer to in the material declaration. In order to tell a "matte" material to use a checkerboard texture for diffuse reflectivity, in this example you would type:

Material "matte" "texture Kd" "checks"

Again, note that you refer to a texture, you type "texture param" "name" where param is the parameter you want the texture to modulate and name is the name you have assigned the texture. color refers to the texture type which can be "color" or "float". Note the US English spelling of the word.

Texture Types

There is no default texture type. The texture types are:

Type Description
bilerp  !TBD
blackbody Definition of the color temperature expressed in Kelvin. For example:
Texture "LampTemp" "color" "blackbody" "float temperature" [6500]
checkerboard A checkerboard. Useful to visualize the geometry flow.
constant A constant value for a color, expressed in [r g b], for example:
Texture "SolidColor" "color" "constant" "color value" [1.000 0.910 0.518]
dots  !TBD
fbm  !TBD
imagemap A texture defined with an external image.
marble Procedural marble.
mix A mix of two textures based on a third value that can be either a constant or bitmap-based. Useful to define transparency maps.
scale Used to mix (multiply) a bitmap with a color.
uv  !TDB
windy  !TBD
wrinkled  !TBD
blender_clouds Blender clouds procedural noise.
blender_musgrave Blender Musgrave procedural noise.
blender_marble Blender Marvbble procedural noise.
blender_wood Blender Wood procedural noise.

Common Texture Parameters (2D)

Only 2D textures share any parameters: these are 'bilerp','imagemap','uv','checkerboard' and 'dots'. Note that checkerboard can also be a 3D texture and that u,v coordinates are used.

name type description default value
mapping string Texture mapping to use. Can be "uv", "spherical","cylindrical" or "planar". "uv"
uscale/vscale float The scaling of the u/v texture coordinates. Only applies to "uv" mapping. 1
udelta/vdelta float u/v offset for "planar" or "uv" texture mappings. 1
v1/v2 vector The two vectors that define the plane for "planar" mapping (1,0,0) and (0,1,0) respectively

Common Texture Paramaters (3D)

name type description default value
translate vector Translate transformation for 3D texture space 0 0 0
rotate vector Rotate transformation for 3D texture space 0 0 0
scale vector Scale transformation for 3D texture space 1 1 1

Specific Texture Parameters

These parameters are specific to individual texture plugins:

name type description default value
constant::value color/float texture The constant value of this texture. 1
scale::tex1/tex2 color/float texture The textures to multiply by the "scale" texture 1
mix::tex1/tex2 color/float texture The two textures (of the same type) to mix with the "mix" texture. 0 and 1 respectively
mix::amount float texture The degree of mix between the two textures while linearly interpolating between them. 0.5
bilerp::v00/v01/v10/v11 color/float Four values to bilinearly interpolate between. 0,1,0 and 1 respectively
imagemap::filename string Path to the image file to use. Required. No default.
imagemap::wrap string How to wrap the texture using "repeat", "black" (black beyond texture) or "clamp" (clamps to border color) Required. No default.
imagemap::maxanisotropy float The eccentricity of the ellipse used in the EWA algorithm 8
imagemap::trilinear bool Toggle trilinear filtering on from the default (better but slower) EWA algorithm. false
imagemap::filtertype string one of: "bilinear", "mipmap_trilinear", "mipmap_ewa", "nearest". "bilinear"
imagemap::channel string one of: "mean", "red", "green", "blue","alpha", "colored_mean". "mean"
checkerboard::dimension integer Specifies whether a 2D or 3D checkerboard texture is being used. Values can be either 2 or 3. Defaults to 2.
checkerboard::tex1/tex2 color/float texture The texture to use for even/odd squares of the checkerboard. 1 and 0 respectively
checkerboard::aamode color/float texture For 2D checkerboard only - the antialiasing mode to use: "closedform","supersample" or "none". "closedform"
dots::inside/outside color/float texture The colour or the dots/their background. 1 and 0 respectively
fbm::octaves integer The number of octaves to use in the spectrum. 8
fbm::roughness float The "bumpiness" of the texture. 0.5
wrinkled::octaves integer The number of octaves of to use in the spectrum. 8
wrinkled::roughness float The "bumpiness" of the texture. 0.5
marble::octaves integer The number of octaves to use in the spectrum. 8
marble::roughness float The "bumpiness" of the texture. 0.5
marble::scale float Scaling factor for the noise input. 1
marble::variation float moderates perturbation magnitude 0.2

Blender procedural textures emulation

LuxRender includes some code imported (indeed with author's permission) form the Blender sources in order to emulate Blender procedural textures. The list is of supported textures is:

  • blender_clouds
  • blender_musgrave
  • blender_marble
  • blender_wood

A usage example:

Texture "mat_proc::col1" "color" "constant" "color value" [1.0 1.0 1.0]
Texture "mat_proc::col2" "color" "constant" "color value" [1.0 0.0 0.0]
Texture "mat_proc::blender_musgrave" "float" "blender_musgrave"
Texture "mat_proc::mix" "color" "mix" "texture tex1" ["mat_proc::col1"] "texture tex2" ["mat_proc::col2"] "texture amount ["mat_proc::blender_musgrave"]
Texture "mat_proc::Kd.scale" "color" "scale" "texture tex1" ["mat_proc::mix"] "color tex2" [0.900000 0.900000 0.900000]
MakeNamedMaterial "mat_proc" "string type" ["matte"] "texture Kd" ["mat_proc::Kd.scale"] "float sigma" [0.000000] "float bumpmap" [0.000000]
Texture: blender_clouds
name type description default value
type string Color type. One of: 'default', 'color' default
noisetype string Noise type. One of: 'soft_noise', 'hard_noise' soft_noise
noisebasis string Noise basis type. One of: 'blender_original', 'original_perlin', 'improved_perlin', 'voronoi_f1', 'voronoi_f2', 'voronoi_f3', 'voronoi_f4', 'voronoi_f2f1', 'voronoi_crackle', 'cell_noise' blender_original
noisesize float 0.25
noisedepth integer 2
bright float Brightness 1.0
contrast float 1.0
Texuture: blender_musgrave

In order to select this kind of texture in Blender use Blender Texture Button(F6) -> Texture -> Texture Type = Musgrave

name type description default value
blender_musgrave::h float Blender Texture Button(F6) -> Musgrave -> H 1.0
blender_musgrave::lacu float Blender Texture Button(F6) -> Musgrave -> Lacu 2.0
blender_musgrave::octs float Blender Texture Button(F6) -> Musgrave -> Octs 2.0
blender_musgrave::gain float Blender Texture Button(F6) -> Musgrave -> (Ridget Multifractal, Hybrid Multifractal) Gain 1.0
blender_musgrave::offset float Blender Texture Button(F6) -> Musgrave -> (Ridget Multifractal, Hybrid Multifractal, Hetero Terrain) Ofst 1.0
blender_musgrave::noisesize float Blender Texture Button(F6) -> Musgrave -> NoiseSize 0.25
blender_musgrave::outscale float Blender Texture Button(F6) -> Musgrave -> iScale 1.0
blender_musgrave::type string Blender Texture Button(F6) -> Musgrave -> Type (valid values: multifractal, ridged_multifractal, hybrid_multifractal, hetero_terrain, fbm) multifractal
blender_musgrave::noisebasis string Blender Texture Button(F6) -> Musgrave -> Type (valid values: blender_original, original_perlin, improved_perlin, voronoi_f1, voronoi_f2, voronoi_f3, voronoi_f4, voronoi_f2f1, voronoi_crackle, cell_noise) blender_original
blender_musgrave::bright float Blender Texture Button(F6) -> Colors -> Bright 1.0
blender_musgrave::contrast float Blender Texture Button(F6) -> Colors -> Contrast 1.0
Texuture: blender_marble

In order to select this kind of texture in Blender use Blender Texture Button(F6) -> Texture -> Texture Type = Marble

name type description default value
blender_marble::noisesize float Blender Texture Button(F6) -> Marble -> NoiseSize 0.25
blender_marble::noisedepth integer Blender Texture Button(F6) -> Marble -> NoiseDepth 2
blender_marble::turbulance float Blender Texture Button(F6) -> Marble -> Turbulence 5.0
blender_marble::type string Blender Texture Button(F6) -> Marble -> Soft/Sharp/Sharper (valid values: soft, sharp, sharper) soft
blender_marble::noisetype string Blender Texture Button(F6) -> Marble -> Soft Noise/Hard Noise (valid values: soft_noise, hard_noise) hard_noise
blender_marble::noisebasis string Blender Texture Button(F6) -> Marble -> Sin/Saw/Tri (valid values: sin, saw, tri) sin
blender_marble::noisebasis2 string Blender Texture Button(F6) -> Marble -> Type (valid values: blender_original, original_perlin, improved_perlin, voronoi_f1, voronoi_f2, voronoi_f3, voronoi_f4, voronoi_f2f1, voronoi_crackle, cell_noise) blender_original
blender_marble::bright float Blender Texture Button(F6) -> Colors -> Bright 1.0
blender_marble::contrast float Blender Texture Button(F6) -> Colors -> Contrast 1.0
Texture: blender_wood
name type description default value
type string Color type. One of: 'bands', 'rings', 'bandnoise', 'ringnoise' bands
noisetype string Noise type. One of: 'soft_noise', 'hard_noise' soft_noise
noisebasis string Noise basis type. One of: 'blender_original', 'original_perlin', 'improved_perlin', 'voronoi_f1', 'voronoi_f2', 'voronoi_f3', 'voronoi_f4', 'voronoi_f2f1', 'voronoi_crackle', 'cell_noise' blender_original
noisebasis2 string One of: 'sin', 'saw', 'tri' sin
noisesize float 0.25
turbulence float 5.0
bright float Brightness 1.0
contrast float 1.0

Volume

Here are the volume types. Each one is a separate plugin. There is not default type.

  • exponential
  • homogenous
  • volumegrid

Common Volume Parameters

Here are the common parameters for volumes.

name type description default value
sigma_a colour The absorption cross section. 0
sigma_s colour The scattering cross section. 0
g float The phase function asymmetry parameter. 0
Le colour The volume's emission spectrum. 0
p0 point One corner of the bounding box defining the volume calculations. 0 0 0
p1 point The second corner of the bounding box defining the volume calculations. 1 1 1


Specific Volume Parameters

These parameters are specific to individual volume plugins:

name type description default value
exponential::a/b float exponential::a and exponential::b are the parameters in the ae^{-bh} formula 1
exponential::updir vector The "up" direction along which to compute height. (0,1,0)
volumegrid::nx/ny/nz integer Each of these parameters denote the number of voxels in the x,y and z directions respectively. 1
volumegrid::density float[nx*ny*nz] The array of density values. 0

Light

General Syntax:

LightSource TYPE <parameters>

Where TYPE in one of the following:

  • area
  • distant
  • goniometric
  • infinite
  • point
  • projection
  • sky
  • spot
  • sun

There is no default type.

For convenience, it's possible to specify the sunsky light which automatically creates a sun and sky light with the same parameters.

Examples

Here are some examples of light declarations:

Type Code
Point Texture "pL" "color" "blackbody" "float temperature" [6500.0]
LightSource "point" "texture L" ["pL"] "float gain" [1.0]
Spot Texture "Spots::L" "color" "blackbody" "float temperature" [3200.00]
LightSource "spot" "point from" [0 0 0] "point to" [0 0 -1] "float coneangle" [70] "float conedeltaangle" [5]
   "texture L" ["Spots::L"] "float gain" [1.50]

Common Light Parameters

These parameters are applicable to all light plugins:

name type description default value
importance float It is part of the Rendering Hints framework. It is a user defined value > 0.0. It can be used by a light strategy as weight for choosing which light source to sample more (available since v0.7). 1.0

Specific Light Parameters

These parameters are specific to individual light plugins:

name type description default value
area::L color The color of the light. 1 1 1
area::nsamples integer The suggested number of shadow samples when computing illumination from the given light. 1
distant::L color The color of the light. 1 1 1
distant::from/to point The two points defining the light direction. Default is down the z axis. 0 0 0 and 0 0 1
goniometric::I color The color of the light 1 1 1
goniometric::mapname string The filename of the goniometric file (goniometric diagram of light distribution) no default
infinite::L color The color of the light. 1 1 1
infinite::nsamples integer The suggested number of shadow samples when computing illumination from the given light. 1
infinite::mapname string The filename of the environment map for an infinite area light. If not provided, a solid color is used. no default
point::I color The color of the light. 1 1 1
point::from point The location of the point light. 0 0 0
projection::I color The color of the light. 1 1 1
projection::fov float The field of view in terms of angular spread along the shorter image axis. 45
projection::mapname string The filename of the image to project. required - no default
sky::gain float Gain (aka scale) factor to apply to sun/skylight. 0.005
sky::nsamples integer The suggested number of shadow samples when computing illumination from the given light. 1
sky::sundir vector Direction vector of the sun. 0 0 1
sky::turbidity float Turbidity can go from 1.0 to 30+. 2-6 are most useful for clear days. 2.0
sky::aconst/bconst/cconst/dconst/econst float Perez function multiplicative constants. 1.0
spot::I color, texture The color of the light. 1 1 1
spot::from/to point Points defining the axis of the spot light. Default is down the z-axis. 0 0 0 and 0 0 1 respectively.
spot::coneangle float The angle in degrees of the spotlight cone. 30
spot::conedeltaangle float The angle at which the spotlight intensity starts to fade from the edge. 5
spot::gain float The intensity of the spot light  
sun::gain float Gain (aka scale) factor to apply to sun/skylight. 0.005
sun::nsamples integer The suggested number of shadow samples when computing illumination from the given light. 1
sun::sundir vector Direction vector of the sun. 0 0 -1
sun::turbidity float Turbidity can go from 1.0 to 30+. 2-6 are most useful for clear days. 2.0
sun::relsize float Relative size to the sun. 1.0

Surface Integrator

Here are the surface integrator types. Each one is a separate plugin.

  • bidirectional (default)
  • directlighting
  • exphotonmap
  • path
  • distributedpath

Rendering Hints Surface Integrator Parameters

Rendering Hints has been introduced in release 0.7. They are supported by the following Surface Integrators: Directlighting, Exphotonmap, Path.

Common Surface Integrator Parameters

name type description default value
shadowraycount integer Define the number of shadow rays traced 1

Light Strategies

Light Strategies define how the light sources are sampled. There are several strategies available:

  • one - randomly pick a light to sample;
  • all - samples all lights and averages;
  • auto - choose to use "one" if there are more than 5 light sources in the scene and "all" otherwise;
  • importance - uses user defined light importance to pick lights to sample more;
  • powerimp - uses user defined light importance and light power to pick lights to sample more;
  • allpowerimp - uses user defined light importance and light power to pick lights to sample more. Traces at least one shadow ray per light source;
  • logpowerimp - uses user defined light importance and the logarithm of light power to pick lights to sample more;

Specific Surface Integrator Parameters

These parameters are specific to surface integrator plugins. There are no common parameters.

Bidirectional

name version type description default value
bidirectional::eyedepth 0.5 integer The maximum length of an eye subpath 8
bidirectional::lightdepth 0.5 integer The maximum length of a light subpath 8
bidirectional::eyerrthreshold 0.6 float The minimum probability for russian roulette eye subpath termination 0.
bidirectional::lightrrthreshold 0.6 float The minimum probability for russian roulette light subpath termination 0.

Directlighting

name version type description default value
directlighting::lightstrategy 0.7 string See #Light Strategies "auto"
directlighting::maxdepth 0.5 float The maximum recursion depth for ray casting. 5
directlighting::strategy 0.5 string Deprecated. Old version of directlighting::lightstrategy. "auto"

Exphotonmap

name version rendering mode type description default value
exphotonmap::lightstrategy 0.7 directlighting/path string See #Light Strategies "auto"
exphotonmap::renderingmode 0.6 directlighting/path string Select the rendering strategy between "directlighting" (v0.5 rendering mode) and a new mode "path" (available since v0.6). "directlighting"
exphotonmap::strategy 0.5 directlighting/path string Deprecated. Old version of exphotonmap::lightstrategy. "auto"
exphotonmap::causticphotons 0.5 directlighting/path integer Set the size of the caustic photonmap. 20000
exphotonmap::indirectphotons 0.5 directlighting/path integer Set the size of the indirect photonmap. 200000
exphotonmap::maxdirectphotons 0.5 (removed in 0.6) directlighting/path integer Set the maximum number of the direct photon traced. 1000000
exphotonmap::directphotons 0.6 directlighting/path integer Set the size of the direct photonmap. 200000
exphotonmap::radiancephotons 0.6 directlighting/path integer Set the size of the radiance photonmap. 200000
exphotonmap::nused 0.5 directlighting/path integer Set the number of photon used in irradiance computation. 50
exphotonmap::maxdepth 0.5 directlighting/path integer Set the maximum number of specular bounces. 5
exphotonmap::finalgather 0.5 directlighting bool Enables/disable final gather step. true
exphotonmap::finalgathersamples 0.5 directlighting integer Set the number of samples used in the final gather step. 32
exphotonmap::maxdist 0.5 directlighting/path float Set the maximum distance of photon included in irradiance computation. 0.5
exphotonmap::gatherangle 0.5 directlighting float Set photon gathering angle. 10.0
exphotonmap::gatherrrstrategy 0.6 directlighting string Russian roulette strategy to use: "efficiency", "probability", "none" . efficiency
exphotonmap::gatherrrcontinueprob 0.6 directlighting string Russian roulette continue probability. Used when strategy "probability". 0.65
exphotonmap::photonmapsfile 0.6 directlighting/path string If the file exists load the photon maps from the file otherwise save maps to it. None
exphotonmap::distancethreshold 0.6 path string Fallbacks to path tracing when rendering corners in order to avoid photon leaks. Enabled by default. Same value of maxdist

Path

name version type description default value
path::lightstrategy 0.7 string See #Light Strategies "auto"
path::maxdepth 0.5 integer The maximum length of a path. 16
path::strategy 0.5 string Deprecated. Old version of path::lightstrategy. "auto"

DistributedPath

This table has been updated to be version 0.7 compliant.

name version type description default value
path::strategy 0.7 string Strategy to use: "all" samples all lights and averages, "one" which randomly picks a light at each step, "auto" which choose to use "one" if there are more than 5 light sources in the scene and "all" otherwise. "auto"
path::directsampleall 0.7 bool Include diffuse direct light sample at first vertex. "true"
path::directsamples 0.7 integer The number of direct light samples to take at the eye vertex. 1
path::indirectsampleall 0.7 bool Include diffuse indirect light sample at first vertex. "false"
path::indirectsamples 0.7 integer The number of indirect light samples to take at the remaining vertices. 1
path::diffusereflectdepth 0.7 integer The maximum recursion depth for diffuse reflection ray casting. 3
path::diffusereflectsamples 0.7 integer The number of diffuse reflection samples to take at the eye vertex. 1
path::diffuserefractdepth 0.7 integer The maximum recursion depth for diffuse refraction ray casting. 5
path::diffuserefractsamples 0.7 integer The number of diffuse refraction samples to take at the eye vertex. 1
path::directdiffuse 0.7 bool Include diffuse direct light sample at first vertex. "true"
path::indirectdiffuse 0.7 bool Include diffuse indirect light sample at first vertex. "true"
path::glossyreflectdepth 0.7 integer The maximum recursion depth for glossy reflection ray casting. 2
path::glossyreflectsamples 0.7 integer The number of glossy reflection samples to take at the eye vertex. 1
path::glossyrefractdepth 0.7 integer The maximum recursion depth for glossy refraction ray casting. 5
path::glossyrefractsamples 0.7 integer The number of glossy refraction samples to take at the eye vertex. 1
path::directglossy 0.7 bool Include glossy direct light sample at first vertex. "true"
path::indirectglossy 0.7 bool Include glossy indirect light sample at first vertex. "true"
path::specularreflectdepth 0.7 integer The maximum recursion depth for specular reflection ray casting. 3
path::specularrefractdepth 0.7 integer The maximum recursion depth for specular refraction ray casting. 5
path::diffusereflectreject 0.7 bool Enable Rejection for Diffuse Reflection. "false"
path::diffuserefractreject 0.7 bool Enable Rejection for Diffuse Refraction. "false"
path::diffusereflectreject_threshold 0.7 integer The Average Threshold to reject. 10.0
path::diffuserefractreject_threshold 0.7 integer The Average Threshold to reject. 10.0
path::glossyreflectreject 0.7 bool Enable Rejection for Glossy Reflection. "false"
path::glossyrefractreject 0.7 bool Enable Rejection for Glossy Refraction. "false"
path::glossyreflectreject_threshold 0.7 integer The Average Threshold to reject. 10.0
path::glossyrefractreject_threshold 0.7 integer The Average Threshold to reject. 10.0

Volume Integrator

Here are the volume integrator types. Each one is a separate plugin.

  • emission (default)
  • single


Common Volume Parameters

Here are the common parameters for volume integrators. There are no plugin specific parameters:

name type description default value
stepsize float The stepping distance to use along a ray while performing the ray marching algorithm 1