Khronos Public Bugzilla
Bug 302 - <perspective> in <optics>: Formula for calculation of <aspect_ratio> is incorrect.
<perspective> in <optics>: Formula for calculation of <aspect_ratio> is incor...
Status: NEW
Product: COLLADA
Classification: Unclassified
Component: Specification
1.5.0
All All
: P3 minor
: ---
Assigned To: Fabrice Robinet
COLLADA Work Group email alias
:
Depends on:
Blocks:
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Reported: 2010-05-16 05:15 PDT by Heinrich Fink
Modified: 2014-01-07 10:23 PST (History)
1 user (show)

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Description Heinrich Fink 2010-05-16 05:15:33 PDT
hi there,

On pg. 149 in 1.5 spec, and pg. 127 in 1.4 2nd edition spec: 

The "Details" section states to derive the aspect_ratio as the ratio between the angle xFov and yFov (aspect = xFov/yFov). This, however, is mathematically not correct. The correct formula should be: 

aspect_ratio = tan(xFov/2) / tan(yFov/2) 

This accounts for both, 1.4 2nd edition and 1.5 specification. The bug reporter does not allow multiple selections, therefore I selected the most recent.

cheers, 

Heinrich