Two potential bugs

stefanj · Post by **stefanj** » Mon Jan 21, 2008 5:37 pm

I'm on PC, 8 core, using LW9.3 and Kray RC7.

After rendering is done, a black stripe comes over the rendered pixels.

There?s also a problem with crashing when images have been added to a surface, and has lost its reference: ?(none)?.

-StefanJ

Post by **silverlw** » Mon Jan 21, 2008 5:55 pm

8cores! Nice ;D Does this problem occur when you render the scene in lower resolutions also? Does the problem occur with only one core?

NiGMa · Post by **NiGMa** » Tue Jan 22, 2008 5:56 am

I noticed you are using the wrong plugin file, your render window says lightwave 7

stefanj · Post by **stefanj** » Tue Jan 22, 2008 12:17 pm

Silverlw: Yeah, the 8 core mac machines are awesome. We installed XP, though, cause we found slight performance boosts on the Windows system both in terms of OpenGL and rendering. And also cause versions always comes later to Mac, which sucks too hard to live with.

NiGMa: Yeah, you got it. My "auto scan" feature in LW found the wrong plugin. So correcting that sure fixed the black line, plus some irradic crashing behaviour. But in fact, the new version was surprisingly slow compared to the old! I found out that it was my AmbOcc-nodes hooked up to all surfaces' diffusion channel that made it crawl. Turning that off gave me back render performance. So I guess I'm back to rendering a seperate AmbOcc pass using LW, and comping it into the frame in PhotoShop.

A little PS in the end here: Any of you guys have tips when it comes to window glass and reflections? Because the alpha channel features in Kray seem to be a little half baked, I have to use a very inconvenient method of rendering the glass seperatly, and comping it in as a reflection pass in PhotoShop. Suggestions?

-StefanJ

phile_forum · Post by **phile_forum** » Tue Jan 22, 2008 3:43 pm

stefanj wrote:After rendering is done, a black stripe comes over the rendered pixels.

Uh oh. I also saw this today, after a 55-minute render! Very reminiscent of the dreaded antibanding bug from a couple of betas ago. I wasn't present when the render completed so I don't know at exactly what point the black band appeared but it must have been after the antialiasing completed. The band covered almost the entire render.

Lots of LW volumetrics in the scene, and I was rendering a limited region.

I'm using OB6.5 for LW9.2+ on LW9.3.1 32-bit edition, WinXP 64-bit.

UPDATE: I rendered the scene again. The black band reappeared, after the antibanding pass. Also, I saw small black squares in the render prior to antibanding - very much like the old reflection bug from the early days of Kray.

Phil

Post by **silverlw** » Tue Jan 22, 2008 5:05 pm

Could you isolate what causes the black squares and send the scene please? Volymetrics is a bit untested so there might be something there.

phile_forum · Post by **phile_forum** » Tue Jan 22, 2008 5:17 pm

Looks like it is related to antibanding: putting "dither simple;" in the tailer gets rid of the black stripe. However, the black square remains (see below, circled in red).

It's a commercial project, but the client has kindly given permission to release the scene/model to the Kray developers (only). How do I get it to you?

UPDATE: It is related to the hypervoxels. Switching them off (just by unticking the Hypervoxels 3.0 entry on the Volumetrics tab of the Scene Effects panel) cures both the black stripe and black squares problems. Further investigations point to the surface characteristics of the hypervoxels, since rendering with the default hv surface settings works OK.

Phil

Post by **silverlw** » Tue Jan 22, 2008 8:07 pm

You can email me at silverlw@kraytracing.com or support@kraytracing.com
That black dot causes antibanding to fail and render half screen black.

Post by **silverlw** » Wed Jan 23, 2008 10:26 am

Thanx for scene

phile_forum · Post by **phile_forum** » Wed Jan 23, 2008 10:42 am

No problem. One other thing: the bug is also related to the use of a limited area - if you render the scene exactly as I sent it, the black stripe will appear. If you change the size of the limited area, it may not. Very odd!

Phil

Post by **silverlw** » Wed Jan 23, 2008 9:11 pm

Just tried your scene but it renders perfectly for me with limited region. No squares or no black band
Im on lw 9.3.1 and Kray64bit Amd Dualcore 4400+
I will let G look at it also since he runs on intel i think

Darn.. Now you got me playing with caustics and your cool scene... Im gonna send you the scene back with some minor changes when im done.

phile_forum · Post by **phile_forum** » Thu Jan 24, 2008 12:22 am

Silverlw wrote:Im on lw 9.3.1 and Kray64bit Amd Dualcore 4400+

I had a feeling this would be a difficult one! All I can say is that it is entirely consistent here. I'm on an Intel Q6600.

Is 9.3.2 the latest LW beta?

Phil

phile_forum · Post by **phile_forum** » Fri Feb 01, 2008 3:08 pm

Been investigating this scene again and found if I untick "show particles" in the Hypervoxels 3.0 panel, the black stripe does not always appear. However, I still get a few small black squares.

So I guess Grzegorz will have to investigate the volumetrics support a bit.

This render is straight out of Kray - final will require a bit of colour correction & stuff.

Phil

Post by **silverlw** » Fri Feb 01, 2008 4:56 pm

Kray renders that glas very slow and G investigates why.

www.kraytracing.com