Everything related to the integration for Rhinoceros.
By Wynott
#395740
I'm having a problem in a scene with relatively shallow water and caustics.

Although the maxwell sea tiles appear to be seamless (edge vertices are coincident) in the editor, when rendered out the caustics clearly show hard edges where the sea tile edges fall.

The effect gets more pronounced with higher SL numbers, which is why I missed this in the draft stage... Only became really obvious after going to 25.

Any ideas?
#395741
Hard to say without references, but my first instinct would be to disable any bump-mapping (and/or displacement, or mapped transmittance) in the material and see if the behavior persists (if you already know where to expect the artifacts, you can render just a small region to high SL relatively quickly). My reasoning being: where the texture is tiled, you will have a seam, and if the texture is not perfectly seamless, then normals will be bent discontinuously across the seam, producing an effect similar to what I think you are describing.

A corollary would be: leave the bump enabled, but apply non-zero offset to its texture; if the artifacts follow the texture offset, it's likely to be related to what I'm saying above, while if not, then it would be tied to the mesh geometry (generated by the extension) itself.
#395742
OK I think you're definitely on the right track with the bump map...

Disabling it however makes the caustic effect go away entirely, which isn't really a good option.

I think my bump map tiles properly... When I offset it in photoshop it looks visually seamless. It's set to meters. I suppose it's possible that it's not tiling across the surfaces correctly?

Looks to me like something else technical is happening. It's a consistent edge everywhere, not like fading in places as I would expect where the tiling happens to be closer to seamless? I'm not sure if that makes any sense.

Attached screen... maybe helps.

https://drive.google.com/open?id=0B-YR1 ... Hl4RjN1cE0
By JDHill
#395743
Yeah, I'm not sure what to make of that. I can't tell whether that image is using offset in the textures (in other words, whether the effect follows the tiling of the sea, or the tiling of the texture).

I wonder what would happen if you used two (or more) identical BSDFs, with the bump texture parameters (modulating scale, offset, rotation) set up differently in each (and making sure not to use global bump). Just in case your bump map is somehow biased toward one direction or another. I'd also experiment with different bump values (I usually find I don't need much, and that too much just results in ugly/weird shading); of course I don't know what value you are using, but I'm talking pretty low -- in the low single digits.

As this is not really plugin-specific, you might want to post about it in the main forum and see if you get better input there.
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By Mihai
#395753
Wynott wrote:
Mon Oct 16, 2017 8:46 pm

Disabling it however makes the caustic effect go away entirely, which isn't really a good option.
But aren't there any waves in the sea geometry itself? That should be the primary source of caustics and you wouldn't even need to mess with bump maps. Can you pack & go a simple scene to see what's going on?

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