View Full Version : Anybody tried Imporance Sampling with strange results?

12-14-2014, 03:51 PM

I tried to render something with a HDR background (via HDR Light Studio) and the new 2015 importance sampling.
This is the result:

The next one is without importance sampling:

Should I contact support?

12-14-2014, 04:30 PM
Awesome. Yes, I'd send the two pics as well, they might know what it is just by looking. Use that Submit New Report thing on your account page.

12-14-2014, 07:45 PM
In my Dielectric test scene, I got what would appear to be the opposite. With IS on, the render looked great; same as in earlier versions but faster. With IS off, there were salmon-colored soft spots on the ground plane. Nothing hard-edged like yours. Seems to me that the renders should look nearly similar, on or off, but faster/cleaner when on.

12-15-2014, 09:32 AM
Opposite for me too. In all the tests I did, ON produced great results and OFF splotches all over the place. Could you double check your scene? If you're still getting it, may be post it here so we can test.

12-15-2014, 03:23 PM

attached are the objects and the scene (the objects are a mixture of rounding, sub-d and frozen sub-d due to the fact that i don't know what to use when and therefore use everything at the same time).

I can't post the textures as they are not mine.

The HDR panorama is:
08-21_Swiss_A.hdr (15000 x 7500 around 300 mb)

which was a free gift from http://noemotionhdrs.net
You can download it here:

The floor textures I bought some time ago from
It is the wood-flooring-014 set which was part of the wood package I got.

As said, I put the HDR into the background feature of HDR Light Studio. As you can see it gets downsampled there when I use it with the LW plug in. It's for preview, not for final render.

On top of that the schlick's approximation node form
was used. I heard about it in the pluto station thread (but for the render I activated the preprocess switches).

Please also check the image processing in Layout. I use a setup which gerardstrada posted to answer my question about antialiasing. For the render settings erikals introduced the "limit dynamic range" to me in the same thread (and a lot more frindly people shared their know how in other threads).

and now after writing all this, the next render with importance sampling finished. Guess what, no green spots. I don't have a clue what's going on. The only thing I did, was to copy the scene and objects to prepare them for the "for forum" posting and reattached the textures for testing?

Whatever, I post it anyway.

Render with importance sampling

HDR Lightstudio setting