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Posted 27 November 2012 - 07:18 AM
“If I understand the standard right it is legal and safe to do this but the resulting value could be anything.”
Posted 27 November 2012 - 08:02 AM
Edited by Hodgman, 28 November 2012 - 12:29 AM.
Posted 27 November 2012 - 08:24 AM
Posted 27 November 2012 - 08:53 AM
That's what I thought at first, but I was confused with the vector/cone thing. I wasn't sure how the cone would be defined from the vector (how wide should the cone be?)Isn't an azimuth/elevation pair just another way of representing a direction, which is the same thing as a surface normal?
Given two directions, you could define a cone, which could describe some slice of a sphere, which is a solid angle....?
This actually makes a lot of sense - so when they say "integrate over a hemisphere of inward directions" it's just a shortcut to say "divide the hemisphere's surface into lots of infinitesimally small, same-area cells with solid angle and angles "? And they use the solid angle notation for conciseness instead of messing around with double integrals ... right, I think I understand. Thanks!If you want to numerically integrate some quantity over the sphere (often just a half sphere when you are doing graphics), you can quantize the azimuth and elevation and you'll get a partition of the sphere into cells. When you want to sum up you'll multiply the value of the function in a cell times the cell's solid angle. Perhaps that's the kind of usage of solid angles that you have seen?
“If I understand the standard right it is legal and safe to do this but the resulting value could be anything.”
Posted 28 November 2012 - 07:47 AM
Edited by ZBethel, 28 November 2012 - 07:52 AM.
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