BiDir Advanced Settings
Posted: Wed Mar 31, 2010 5:13 pm
I'm trying to do a test render where there is a light source inside of a glass container. If I render the scene with Pathtracing mode, or MLT, I can get the glass to clear, eventually. MLT clears better than Pathtracing. Shadowed areas of the scene, however, remain somewhat grainy, even after rendering to 10,000 samples per pixel.
If I use BiDir with either rendering method, the glass container the light is in ends up with a number of ugly spotty artifacts that never clear, no matter how long I leave the rendering to cook. Almost like the glass has a number of tiny imperfections or bubbles in it, distorting what can be seen through it.
My question is, are there some "better" settings to use than the defaults in the "Advanced Settings"? I tried smaller (0.001) and larger (0.1) settings for Max Change, each of which had a dramatic effect on the quality of the render but really didn't solve the problem. (The smaller value made the render look like a kind of sketchy Van Gogh, the higher value make the glass look like a Serrault - all dots.) I'm doing a test right now with the Max Num. Consecutive Rejections set to 500 (from the default of 1000). But basically I'm muddling around in the dark. The MLT render without BiDir produced the cleanest results (aside from the shadows) but took a fairly long time.
Is this a limitation of BiDir, or a flaw in the algorithm?
I'll post some demonstration renders once this latest test finishes rendering some time tomorrow. But I thought maybe someone would have some advice on other setting adjustments to try. The scale of the test scene is small - the objects are in the 10cm to 15cm range in size (a drinking glass, a glass container with a cylindrical light, and a solid sphere).
If I use BiDir with either rendering method, the glass container the light is in ends up with a number of ugly spotty artifacts that never clear, no matter how long I leave the rendering to cook. Almost like the glass has a number of tiny imperfections or bubbles in it, distorting what can be seen through it.
My question is, are there some "better" settings to use than the defaults in the "Advanced Settings"? I tried smaller (0.001) and larger (0.1) settings for Max Change, each of which had a dramatic effect on the quality of the render but really didn't solve the problem. (The smaller value made the render look like a kind of sketchy Van Gogh, the higher value make the glass look like a Serrault - all dots.) I'm doing a test right now with the Max Num. Consecutive Rejections set to 500 (from the default of 1000). But basically I'm muddling around in the dark. The MLT render without BiDir produced the cleanest results (aside from the shadows) but took a fairly long time.
Is this a limitation of BiDir, or a flaw in the algorithm?
I'll post some demonstration renders once this latest test finishes rendering some time tomorrow. But I thought maybe someone would have some advice on other setting adjustments to try. The scale of the test scene is small - the objects are in the 10cm to 15cm range in size (a drinking glass, a glass container with a cylindrical light, and a solid sphere).
