CompuServe Messages

#Aspect ratio?

    26-Feb-95 23:12:01
Sb: #Aspect ratio?
Fm: David Gould 100424,2533
To: Erik Reitan 76702,1321
Could you please give me some more detailed information on how 3DS uses the "Aspect Ratio" setting to determine the output pixel? Specifically I want to know how you derive the settings: 640×480 with 1.0 aspect 320×200 with 0.82 aspect Is it: 480/640 x 4/3(aspect ratio of the computer screen) = 1.0 200/320 x 4/3(aspect ratio of the computer screen) = 0.82 For example from a camera viewport I start a rendering at 640x480x1. Since the viewport I see from the 3D Editor isn't exactly the same shape as the final output how can I be exactly certain that what I see in the 3D Editor will appear in the final rendering? The only way I can be sure is by experimentation, which isn't very accurate. How does 3DS determine the area covered by the final image? Does it use the centre of the viewport as the middle of the final image then determine, using the aspect ratio and width and height of the final image, the exact area of the actual scene to be displayed? If this is the case then I can scale the image in half horizontally by using 240×480 with an aspect ratio of 2 rather than creating an image of 640×480 with an aspect ratio of 1 and then using video post to shrink it by half horizontally. So, it seems, that it is possible to perform a wide variety of different images scales simply by altering the image width, height, and most importantly, the aspect ratio directly in the renderer rather than altering an original image. Am I correct and could you please give me details on how 3DS maps from scene coordinates to image coordinates? Thanks. David "A_spect in my eye" Gould