#Aspect ratio?
5 messages in this thread
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
Hi,
During the Renaissance, the perfect frame must had a dimension of 4 unity long
and 3 height. In a 640 x 480 you got that ratio (160×4)(160×3). So we say that
the aspect ratio is perfect or have a value of one. In a 320×200 the aspect
ratio is not 1. To have a ratio of one the height must be at 240 instead of
200. To find the aspect ratio of a non classical frame :
(320×200)the irregular / (320×240)the classical = .833333.
Have a good day,
Pierre
The Aspect Ratio as referred to by the 3DS Rendering Configuration
dialog box is the aspect ratio of the _pixels_, not of the overall
screen. The specified resolution (width x height) designates the
aspect ratio of the overall screen. Some display resolutions have
different pixel aspect ratios than others.
<<The Aspect Ratio as referred to by the 3DS Rendering Configuration dialog box
is the aspect ratio of the _pixels_, not of the overall screen.>>
I was aware of this I just wanted to find out the formula/algorithm used to
determine the final area of the scene covered by a single pixel. It appears
this is dependent on the pixel shape(aspect ratio) and the aspect ratio
produced by the image height/width ratio. Could you please give me more
details?
Thanks.
David "Many aspects" Gould
Hi David,
<< I was aware of this I just wanted to find out the formula/algorithm used to
determine the final area of the scene covered by a single pixel..>>
I can't help you with the formula but on a similar but not-too-related subject,
have you review the following file?
File Info for CAMERA.ZIP
Section: Software Dev. Kits Contributor: 73172,1351 Size: 7511
Submitted: 5/19/94 Type: Binary Accesses: 71
Title: Thread outlining a test of 3ds FOV
Keys: 3DS FOV CAMERA
A thread primarily between John K. Jordon and Michael E. Bartlett and their
scientific experiments to test the accuracy of 3DS' cameras FOV.