LuxRender Cameras - LuxRender Wiki
Luxrender GPL Physically Based Renderer

LuxRender Cameras

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LuxRender supports three different camera types. The differences between the camera types and the available settings are explained below.

perspective, orthographic and environment camera


Contents

Perspective Camera

The perspective camera is a camera type that is similar to cameras in most 3d packages: it does create a perspective image out of a three dimensional scene, but it does not aim to represent the imperfections and distortions that lenses of photo cameras typically create.

Field of View

The value for field of view indicates the angle between the camera and the leftmost and rightmost visible points in the scene (or the top- and bottommost points, if the image is vertical). The exporter normally gets this information from the selected camera in the scene, but the value can be overridden.

view angles of 70, 40 and 20 degrees


Depth of Field: lens radius, f-stop, focus distance, and light distribution

Depth of field indicates how sharp (infinite depth of field) or blurred (shallow depth of field) objects that are not in focus appear. For the perspective camera in LuxBlend, this is defined by the "lens radius" which calculates aperture diameter, or the f-stop value, f-stop being 1/focal length, thus larger f-values will result in a smaller aperture diameter and thus deeper depth of filed. The default lens radius value (0) calculates at infinite f-stop, and thus an image where everything is in focus. Larger lens radius values result in a more shallow depth of field.

The alternative method (and only one available in LuxBlend25) is to define an f-stop value in the camera tab (This is the method used on real cameras). With f-stop, smaller numbers create a more shallow depth of field.

Focus distance is the distance between the imaginary plane in the scene that will be in focus and the camera imaging plane. You can either use an object or a distance to set the focus distance. An easy way to use this feature in Blender is to create an Empty object, place it where you want the camera to focus and select it in Depth of Field box.

Various lens radius settings, from left to right: 0, .05, .1
Note that for the different examples, the focus distance is the green sphere in the front. As the lens radius increases, the background becomes more blurry. Lens radius setting is not currently available in LuxBlend25


Various f-stop settings, from left to right: .5, 1.5, and 4
Note that for the different examples, the focus distance is the green sphere in the front. As the F-stop is increased the background objects become more in focus


LuxRender also allows for some modifications to the distribution of light across the focus disk or circle of confusion. The distribution and quality of this light is generally called bokeh. This is achieved through the blade number and distribution parameters. Blade number is the number of blades that make up the iris of a lens. A blade number of zero simulates an infinite blade number of a perfect circle, and will result in bokeh disks that are circular. Almost all lenses, when wide open, have their blades concealed behind a circular disk in the lens, and thus are circular, but at any other f-stop, the light traveling through the lens is exposed to the blades, and their number and shape will be revealed by the shape of the bokeh disks in the image. More expensive lenses traditionally have more blades, eight or more, while cheaper lenses average six. As no lens distributes light uniformly across the focus disk, some non-uniformity is desirable for photorealistic imaging. Refer to the images below for a starting point for these parameters.

Uniform depth of field light distribution across the bokeh disk at power settings of 0, 10, and 100, with a six bladed iris.
Note that the power setting has little or no effect on the uniform distribution parameter, remaining uniform.


Exponential depth of field light distribution across the bokeh disk at power settings of 0, 1, and 10, with a six bladed iris.
Note that at the power setting of 0 the lens closely mimics the light distribution of a catadioptric lens.


Inverse Exponential depth of field light distribution across the bokeh disk at power settings of 0, 1, and 10, with a six bladed iris.
Note that this is simply the inverse of the exponential setting, and that higher power settings closely mimic a catadioptric lens.


Gaussian depth of field light distribution across the bokeh disk at power settings of 0, 1, and 10, with a six bladed iris.
Note that the power setting has little or no effect on the non-uniform distribution of light across the bokeh disk.


Inverse Gaussian depth of field light distribution across the bokeh disk at power settings of 0, 1, and 10, with a six bladed iris.
Note that the power setting has little or no effect on this no-uniform distribution of light across the bokeh disk.


Shutter

The shutteropen and shutterclose entries in the .lxs file are typically used for Motion Blur.

Lens Shift

A shift lens is a lens that can move the position of the horizon up or down without introducing perspective distortion in the vertical direction. Amongst others, this can be useful for architectural perspectives where most of the subject is above the horizon.

The unit of measurement for lens shift is the size (either horizontal or vertical, depending which of the two is biggest) of the image. For example, using a horizontal value of 0.5 will result in an image whose left edge is straight in front of the camera.

a normal perspective view from a horizontal camera; the same view with the camera tilted vertically; the same view using lens shift instead of camera tilt


Clipping

Camera clipping hides part of the scene, based on the distance to the camera plane. There are two settings, Start and End. When Start is set to 0 and End to a value bigger than the size of the model, everything will be visible. The geometry that is hidden by the camera clipping is still taken into account for the lighting calculations.

no camera clipping; start set to 30; end set to 50


Orthographic Camera

The orthographic camera creates an orthographic projection of the scene. This can be used to create straight projections (like a top view or a frontal view) and axonometric projections.

a camera that is looking in a horizontal or vertical direction creates a projection, a tilted camera creates an axonometric view


Scale

The scale value sets the scale of the view. The scale number indicates how many model units fit in image. For example, at a scale of one, one model unit will fit exactly in the width of the image (or the height, in case the height is bigger than the width) and at a scale of one hundred, one hundred model units will fit in the image.

Clipping / Depth of Field / Focus Distance / Shutter / Lens Shift

These settings work the same way as the perspective camera settings.

Environment Camera

The environment camera creates a 360 degree image from the current camera position. If the camera is completely horizontal, this results in a panoramic image. Amongst others, this can be used to create high dynamic range environment images for image based lighting.

rendering generated with an environment camera

Clipping / Focus Distance / Shutter

These settings work the same way as the perspective camera settings.