Hi Larry,
Thanks for the quick response. We have spherical harmonic coefficients stored
in Pixar's env maps. I am trying to swap us to use OpenExr's env maps (via
OpenImageIO in a RSL Plugin ). This will allow us to control the caching of
this LUT separate from PRMan's texture cache. When I read in the two maps, the
values differ by as much as 0.1. I am pretty sure I have accounted for the
difference in env map encoding between the two. I wrote a little python script
to create the unit sphere for the two encodings. Rendering with the two unit
sphere maps also gives me at least 0.03 in error. Increasing the resolution
decreases it to some extent. I am pretty sure I am point sampling the tex file
too. But, I am checking with the PRMan folks to make sure.
Would you expect so much error between the two? Any ideas on where I may be
going wrong?
Thanks,
Ryan
On Thursday, November 14, 2013 6:58 PM, Larry Gritz <[email protected]> wrote:
Yeah, that looks like it should do it. Between the zero derivatives and the
width==0, and the InterpClosest (to prevent true interpolation), you ought to
be point sampling.
Is this not working as expected? What happens?
On Nov 13, 2013, at 9:53 PM, ryan heniser <[email protected]> wrote:
How do I point sample a env map with an environment call? I thought it would be
something like
>
>// Initialize texture options for point sampling
>gTexOpts.nchannels = 3;
>gTexOpts.firstchannel = 0;
>gTexOpts.swrap = TextureOpt::WrapPeriodic;
>gTexOpts.twrap = TextureOpt::WrapClamp;
>gTexOpts.samples = 1;
>gTexOpts.mipmode = TextureOpt::MipModeNoMIP;
>gTexOpts.interpmode = TextureOpt::InterpClosest; // Force closest texel
>gTexOpts.conservative_filter = false;
>gTexOpts.sblur = 0;
>gTexOpts.tblur = 0;
>gTexOpts.swidth = 0;
>gTexOpts.twidth = 0;
>
>
>const Imath::V3f zero(0,0,0);
>
>bool ok = gTexSys->environment(filename, gTexOpts, r, zero, zero, test);
>
>
>Ryan
>_______________________________________________
>
>
--
Larry Gritz
[email protected]
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