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Artefact dots in pine leaves
show user profile  McArno
Hi,

I'm having a problem with bright dots in the middle of the pine tree. Weirdly this is only visible on the RGB pass, not in lighting, GI, reflections, refractions etc. I'm using V-Ray as rendering engine and also it's native materials. Since it is only happening with the pines, it should be a material related issue, but I haven't been able to figure it out.

Any suggestions would be kindly appreciated.

dots_in_pines.jpg
read 299 times
4/28/2016 2:20:54 PM (last edit: 4/28/2016 2:21:23 PM)
show user profile  9krausec
Here is what I would do until I found honed in on the issue (not saying it's right). Also the below probably isn't applicable as these artifacts aren't showing up in passes, but...

Turn off GI
test render
Apply same simple material to everything (or vray material override)
test render
Turn off all lights and replace with single dome light w/o any texture
test render
Export as OBJ/Alembic - Import
test render

How are you setting up your materials? I assume opacity maps for the pines or are they actual geo? If so I'd look at how you are generating the opacity. Maybe cut the opacity map and test render to see if that is the source of the problem?

Just spit balling. Break it down until you find the issue.






- Portfolio-




read 278 times
4/28/2016 7:41:51 PM (last edit: 4/28/2016 7:41:51 PM)
show user profile  FX
From the looks of it the material on the front tree is the issue, it's creating the dots only where it overlaps the trees at the back.
I've never seen dots like that before, looks like unfinished pre-passes.

read 265 times
4/28/2016 9:34:17 PM (last edit: 4/28/2016 9:35:33 PM)
show user profile  McArno
Thanks for your feedback.

I'm using Vray 2 sided material. Tried disabling translucency map, no effect. Changed Opacity map blur from 0,01 to 1 which coused major white areas.
For lighting I'm using HDRI dome light, no other light sources.
Disabling Opacity map loses dots, but of course it makes all twigs look like blocks.

So finally I decided do create my own opacity map (instead of using default Evermotion one) and now it renders just fine. Don't know why there's a difference in render, as in visual observation they look the same.

I made a comparison image of the textures in case anybody is interested to see the difference:
pine_leaf_comaprison.jpg
read 252 times
4/29/2016 11:52:30 AM (last edit: 4/29/2016 11:53:33 AM)
show user profile  FX
Ah, Evermotion "Ready to Render".....badly :)


read 247 times
4/29/2016 11:55:53 AM (last edit: 4/29/2016 11:55:53 AM)
show user profile  TiMoN
Pine trees have needles though, not leaves..
My unhelpful comment for the day. Carry on.

Terribly boring signature.
read 239 times
4/29/2016 1:21:19 PM (last edit: 4/29/2016 1:21:19 PM)
show user profile  9krausec
That's interesting McArno as an opacity map is just a simple black and white map. I would be curious as to the format of evermotion's opacity map and the one you created..

Also it's interesting to note that Renderman vs Arnold vs Vray all handle the same opacity maps differently (as far as the output).





- Portfolio-




read 231 times
4/29/2016 3:20:29 PM (last edit: 4/29/2016 3:20:29 PM)
show user profile  FX
The original map looks pixelated, maybe needed a slight blur.


read 229 times
4/29/2016 3:22:35 PM (last edit: 4/29/2016 3:22:35 PM)
show user profile  McArno
I tinkered on with my own opacity map, by deleting almost half of the needles (to have less dense looking pine branches in render). However, what is interesting there, is that as I made it less dense, the rebel bright pixels came back.
I tried to remedy the situation by increasing rendering resolution from FullHD to 4k, but it only made bright pixels smaller (see attached image>). I also lowered color thrs to 0,014 and noise trsh to 0,03.
pine_with_bright_pixels.jpg

@9krausec > Both opacity maps are 8-bit RGB JPG-s.
@FX > Blur wouldn't probably help much. Though the original map had some tiny needle deletion leftover stripes on the map. I originally suspected those to be guilty of the bright pixel syndrome, but it seems it's because of the less dense opacity map...
read 216 times
4/29/2016 9:05:06 PM (last edit: 4/29/2016 9:12:46 PM)
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