LuxRender Cameras
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LuxRender supports four different camera types. The differences between the camera types and the available settings are explained below.
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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.
depth of field: lens radius and focus distance
The 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, this is defined by lens radius. The default value (0) results in an image where everything is in focus. Larger values result in a shallower depth of field.
Focus distance is the distance between the point in the scene that will be in focus and the camera plane.
note that for the different examples, different objects have been used to focus on; the Lens Radius value does not influence the focus distance
shutter
The opening and closing time of the shutter can be entered here. This will be useful once a motion blur feature has been implemented.
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.
clipping
Camera clipping hides part of the scene, based on the distance to the camera plane. There are two settings, hither and yonder. When hither is set to 0 and yonder 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.
realistic camera
As its name indicates, the realistic camera is the camera type that most closely matches a real photographic camera. The difference between this camera and the ordinary perspective camera is that the realistic camera calculates the way light is distorted by the lens, whereas the perspective camera uses a much simplified camera model that resembles a pinhole camera. Hence, the realistic camera is capable of showing lens characteristics like barrel distortion and vignetting. LuxRender contains camera data for a small number of cameras; these can be chosen as a preset. It is also possible to supply your own camera model if you happen to have this information available as a .dat file.
field of view
The lens data file of a realistic camera corresponds to a camera with a certain focal length. However, the program can generate a similar lens with a different focal length (and thus field of view) by scaling the lens data.
film size
This value indicates the size of the diagonal of the camera film in millimeters.
film distance
This value indicates the distance between the film and the backmost lens element. Changing this to a different value than the default for the lens will result in an image that is out of focus.
aperture
The depth of field can be influenced by setting the aperture of the camera. The values correspond to the ones found on a real photographic camera; lower values result in a shallower depth of field.
camera data file
The realistic camera can use one of the four preset cameras, or it can use a user provided .dat file. Such a file needs to be in the file format as indicated in the paper by Kolb, Mitchel, and Hanrahan.
focus distance / shutter / clipping
These settings work the same way as the perspective camera settings.
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.
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.
clipping / focus distance / shutter
These settings work the same way as the perspective camera settings.