CompuServe Messages

#Radiosity

    31-May-95 16:48:14
Sb: #171481-#Radiosity
Fm: Paul Lempke 71460,1037
To: Marion K. Marks 70700,2777
I enjoyed catching up on this thread and a have a few comments -FWIW. 1, 2, & 3 point perspective are manual construction techniques that don't bear much resemblance to the algebraic perspective method used by typical 3D renderers wherein a point in space is projected onto a frame standing between the object and the viewer. If you hold an empty frame up in front of you and look down the hall, you will see that straight lines really are straight. The frame that we view graphics through determines a lot of how we percieve these things and since the frame is itself an external object in our field of view our perception of it is subject to illusion as well. If the image is large enough to immerse yourself in, then the image/object will exhibit the same distortions that you mentioned -it is a matter of scale and reference. One cheap way to distort your images is to cut a matte that bows in slightly all around -the matte will look straight and the image will have the curvature that you are looking for. This essentially corrects for the disparity in scale between the scene and the size of the rendering. ( Ever notice how Zenith flat CRT's always appear to bow in?) Hand held prints of small objects in a shallow space should need no predistortion. Similarly wide screen movies of architectural spaces shouldn't either, but when you squeeze a building into a TV set then you might want to. An image processing routine (IXP) should work fine, I bet Mirage would do it.