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In this section, we will discuss the screen-to-raster projection, whose job it is to figure out how to get that screen rectangle onto the raster.
Screen-to-raster geometry
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Perspective (l) and Orthographic (r)
Screen Window
The screen window is the rectangle which is the intersection of the perspective viewing pyramid or orthographic viewing box with the screen plane and can be set for each camera. It is this rectangle which is then projected onto the display device by the screen-to-raster transformation.
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Take care when using field of view and screen window at the same time. The field of view does not specify the viewing angle through the specified screen window -- it specifies the viewing angle through the (-1,1,-1,1) window by moving the screen plane. The screen window is then computed relative to this moved screen plane. In practice, this is hard to control, and is only used in rare circumstances.
Field of view geometry
Conclusion
The viewing transformation has lots of controls, but typically they are not all used together. Rather, a couple important controls are set and the rest are left at their default values. There are a few simple rules to follow when tuning the viewing transformation:
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