Strange artifacts

[daug]

Unfortunately LW's content manager does not handle content on different drives so it just quits. I don't want to spend $50 on a plugin that I will not use more than a couple times. The scenes has enough images and objects in it that I don't want to shuffle around the content manually. Any other ideas?

[phile_forum]

I've run into a very similar problem today. Little black squares showing up on glass areas. My glass recipe has gradients on both transparency and reflectivity - not sure if that's a factor but I thought I'd mention it.

Anyway, the problem for me was definitely related to undersampling. Switching this off appears to eliminate the black squares.

Phil

Edit

Turns out it's not that simple after all. Just did another render of the same scene with no undersampling but much lower FG settings and the black squares are back. Smaller, but back. They cluster on reflections. It's possible they are associated with reflections of reflective surfaces.

[daug]

Although I haven't had much time to mess around with the scene, I noticed that even after removing my glass object and turned off undersampling, I still had some minor black squares also.

[phile_forum]

Odd, but here it is... The black squares only appear in the second and subsequent times I render with Kray. The first render after starting LW is always black-square-free.

Here's the test:
1. started LW. Rendered -> no black squares.
2. Rendered again without changing any settings at all -> black squares appear.
3. Quit LW.
4. Restart LW.
5. Rendered -> no black squares.
6. Rendered again -> black squares reappear.

NB the shared GI file setting was set to Save, so it's not an effect from loading an old GI file because I'm calculating a new one each time.

Phil

[jure]

That is realy weird thing. Would it be possibly to post your bugy scene so I can try it in beta version and see if it's fixed allready?

[phile_forum]

Right, I seem to have identified the cause of the problem. It's a pretty specific set-up in my case!

One of the surfaces in my scene has a bump channel with a gradient layer. This gradient layer was supposed to use a weight map as its input parameter, but the weight map was missing - I guess I originally made the surface for another model and then re-used it in this scene.

Disabling the layer with the incorrectly assigned weight map cures the problem - I can now make the black squares come & go at will.

Note, however, that the black squares do not appear on the faulty surface itself, but on transparent or reflective surfaces elsewhere. There is still also the unexplained weirdness regarding the first render being OK and subsequent ones showing the black squares.

Anyway, here is a test scene which, on my system, will render OK the first time, but show black squares after that. To kill the problem, simply untick the top layer of the bump channel in the surface called PVC.

I'm using Kray 1.612 demo on Lightwave 7.5d

Phil

[jure]

Thank you for this scene! I'll pass it forward to G. to fix this bug.

[phile_forum]

I notice a few people have downloaded the scene now. Has anyone replicated the problem?

Just interested...

Phil

[jure]

Yes I've tested it and I get the same bug problem here. But it will be fixed in next release.

[gtanski]

Its another incarnation of
http://www.kraytracing.com/forum/viewtopic.php?t=205
and
http://www.kraytracing.com/forum/viewtopic.php?t=124

or it does not appear anymore. That could be missing uv map bug, that was fixed some time ago.