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View Full Version : Strangeness in wind glass render, possibly with regard to caustics and reflection.



Beerbaron
05-01-2010, 06:42 PM
I am doing a wine glass, and it is having some issues:

http://img62.imageshack.us/img62/3297/wineglassd.jpg

Firstly, there is some reflection strangeness, just below the rim of the glass. It looks like the inside of the glass is reflecting some of the gold treatment around the lip, but from the geometry of the glass and the camera angle, it shouldn't be there, and it looks very strange.

Secondly, in the base of the glass are a lot of very dark patches, probably from caustics, that I don't like. I tried to put an area light behind the glass to try and make some fill, but it didn't help. How can I deal with this?

Any other suggestions about the image would be appreciated. Thanks.

Beerbaron
05-01-2010, 07:35 PM
Even from a higher angle, there are strange reflections around the lip:

http://img532.imageshack.us/img532/1216/higherangle.jpg

Beerbaron
05-01-2010, 08:46 PM
Adding some geometry near the lip fixed the first issue, but the other issue remains:

http://img440.imageshack.us/img440/3682/corrected.jpg

serge
05-02-2010, 04:56 AM
If it's the reflection of the black background, then it's correct. What happens if you change the colour of the background?

Also, what happens if you check the "Limit Dynamic Range" option (under Image processing)? This could help with some AA issues I'm seeing.

Lastly, I don't suspect this to be the case, but if you've set the Ray Recursion Limit very low, you could try increasing that.

Iain
05-02-2010, 04:57 AM
Caustics in LW are flaky to say the least.
To get the best from them, use a light just for that purpose that doesn't affect anything else and position it close to the glass.

Mess around with the settings but accuracy has to be really high (into the thousands if I remember my tests) and crank up the AA.