William F Pokorny <ano### [at] anonymousorg> wrote:

> Bill W. - Is there a reason for using uv_mapping with map_type 0 over
> map_type 1 only in the image_map block? I think what you have OK, but
> it's not how I would have coded the mapping. :-)

Well I didn't code it either - IIRC, it was a code block that someone suggested
when I was trying to use an hdr environment to get a better looking render.

The scene looked flat, and I figured that maybe he was just using a "background"
and not exploiting the full benefit of the (what seemed to me to be) and hdr
image.

So I just dipped into the archive, found the scene, and copy-pasted.

"Because I'm lazy, and don't know anything about all those specialized options
and flags....?"  :)

Good points below, I figured there was also some sort of randomization invoved
with radiosity, but didn't know what, or if it was user controllable.   I just
felt that we'd deal with that issue if and when it came up.

> Random thoughts / questions.
> ---------------------------
>
> - With .exr and .hdr images the file gamma should always be left at 1.0.
> These files have values in both the [0,1) range and [1,1+]. This means
> any gamma other than 1.0 creates adjustments which move in opposite
> directions depending upon whether particular color channel values at a
> given pixel <1 or >=1. It 'should be' any .hdr, .exr file one finds out
> and about was written at a gamma of 1.0. IIRC, POV-Ray itself cannot
> write .hdr / .exr files at other than 1.0.
>
> - With .exr and .hdr images, interpolation is I believe iffy. The image
> interpolation code was written for [0,1] ranges. I usually use no
> interpolation with high dynamic range images and move to higher
> resolution environment maps if need be. However, I've not 'really'
> looked at how the different interpolation options work with typical .exr
> and .hdr images.
>
> - With respect to blotchiness frame to frame, remember, v3.7 introduced
> the radiosity high reproducibility option. Use High_Reproducibility /
> +HR on the command line or in the ini file. An more reliable alternative
> is to use single threads for each frame (+wt1). This, though, might lead
> one to manually break up the rendering of frames into buckets to make
> use of all your cores / threads.
>
> - Puzzling to me - some of the dark grid lines on the screen flicker in
> and out of existence during the render...? Unsure why this would happen
> unless perhaps using method 3 anti aliasing? If using method 3 remember
> you need to specify the seed used (can't recall the ini/command line
> option +ss maybe?) to keep results consistent render to render.
>
> Bill P.

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