View Full Version : Texture changes over Screamernet

07-10-2007, 11:28 AM
I have a sphere textured with the standard layer system. It has three texture layers for color only:
1. Dented colored blue at 70% opacity, Additive Blending, no env, no ref obj.
2. Previous Layer mode Gradient with three color keys from white to green.
3. Turbulence colored 255 white, no env, no ref obj.
Base color = 0 black, Lum= 100%, Dif = 0%, Spec = 0%, Trans = 0%, and Ref = 0%.

When rendered over Screamernet, the Dented texture is being rendered differently on each machine as though they are using a different seed value... that is, the pattern of the texture for only the Dented layer changes, the Turbulence texture layer remains fixed. The textures are all rather large and devoid of high-freq detail so they appear blurry since this is a reflection/refraction environment for shards of broken glass as well as a background element, so the pattern shift isn't too noticeable in the rendered images, especially since it's just the additive blue splotches that are changing and not the prominent base white to green Turbulence.

All the rendering machines are identical (a lab of 12 Dell Precision 490's all having the exact same hardware and OS/software image using Ghost). Screamers are using the -3 mode and are told to render batches of 50 frames each (of a 1600 frm animation), so it's easy to spot when the texture jumps from one pattern to another. In fact, this change in Dented texture even occurs on SINGLE machines running 2 instances of LWSN!!

What could be the cause of this?

07-10-2007, 11:38 AM
These two images demonstrate the issue, which doesn't show up until frames 765/766 (16 and 66 being the transition frame number between batches of 50 frames for each screamer instance... that is, rendering started on frame 216, thus one node renders 216-265, the next 266-315, the next 316-365, etc, etc.)

Do an A/B compare to see the shift in the blue splotches.

07-10-2007, 07:06 PM
I didn't notice such thing before on my LWSN, but if you want quick way to fix it - bake procedural texture to image, after that it'll be the same..

07-12-2007, 12:10 PM
I'm wondering if it has something to do with the blending mode or that particular procedural (dented).

I guess by the silence no one has experienced this or has an answer. The potential problem with baking textures is what if I had this one animated.

Well, if no one has time on their farm to render a quick test with Dented set to Additive over normal Turbulence, then I guess I will have to investigate further when this particular project is done in a week or two. Just wish I could find out sooner from someone in this network.

07-12-2007, 12:30 PM
If you will provide example scene & objects, I will try rendering it..

07-12-2007, 02:01 PM
I've also had a similar problem. Sometimes, one or two nodes would spit out frames with textures that looked like they were using a different seed value. But if I would stop the render and start again, they may be fine and others would do this. This would happen across pc's that had different processors but it would also happen across our Dell Bladeserver which (in theory) has all identical processors. It doesn't always happen but when it does I end up wasting a lot of time deleting the offending frames and re-rendering and watching to make sure another node isn't doing the same thing.

07-13-2007, 09:34 AM
Like I said, it's just a sphere with the three texture layers as I explained above, nothing hard to make yourself, but here it is anyway. Thanks for the help. I wish Newtek would address this thread.

10-16-2008, 10:48 AM
Bumping this old thread because the latest version of 9.5 still has this problem.