I’ve been working on rendering the particle hair I made with the PRT Hair modifier and I’ve run into two separate (I think) issues.
Whenever I try to save out a partition of the PRT Hair, so I don’t have to deal with the extra file bloat of the Hair and Fur modifier, and bring it back in via a PRT Loader, it always renders as a paler version of the PRT Hair render. It’s like the Gamma got screwed up or something. I save out a single partition and when I bring it back in with the PRT Loader the particle count is exactly the same as the PRT Hair particle count. So I’m not missing anything and I don’t think loading in more partitions would help. I’ve attached a pic comparing the two in the RAM viewer.
The other issue involves the Shadow Generator. You can see in the V-Ray render of the girl that there is a weird shadow artifact on the side of her cheek and I can’t seem to figure out what is causing it. I had the same problem generating shadows for the hair on her head too. Parts of it were fine, but there were areas in shadow that were not supposed to be. Could this have something to do with my Matte Objects? Do Matte Objects need to be fully enclosed geometry? The back of the model has some missing geometry that I cut out because I thought it wasn’t necessary… I’m using three Max spotlights to light the scene and I’m generating shadows with all of them.
Regarding the first issue - are you using the Marschner Hair shader? If yes, did you remember to save both Normal and Tangent channels when you output your particles? If you forgot the Tangent, the shading would be off because the shader depends on both channels! You can see this when looking at the Memory Channels rollout - anything listed on it should be available when rendering, and if you forgot to save one of those channels, it would explain the difference…
Regarding the shadows generator problem - what type of light are you using? Omni, Spot or Direct?
If it is Omni, have you tried a Spot?
Ah, okay. I wasn’t aware that it was necessary. But now it makes sense. If I had used a Per-Particle Channel for one of the Marschner parameters, I would probably have made the connection earlier that I would need to add that particular channel to the save list as well.
Thanks for that! Sometimes it’s the simplest stuff that proves to be the most perplexing to fix!
As for the lights, yes, all three are Max Spotlights. All the Max settings are default except that Decay = Inverse Square.
They all have the same Krakatoa Shadows settings:
Resolution = 1024
Sample Count = 5
Sample Spacing = 0.15
Exponential Spacing is on (default)
Geometry Shadows are on and set to V-Ray Shadows
Transparent Shadows = on
Area Light is checked on
Samples = 64
Hmm, I am unsure what the cause for that shadow problem is. I am sure you could turn shadows on and off to figure out which one is causing it. But I don’t think there is an obvious problem with your settings. That being said, computers tend to do what we tell them. There must be something that in the end of the day will make sense of sorts I just don’t know what it is…
Thanks, Bobo. While trying to figure out the problem I turned off all the lights except for one and checked them in turn. Each light individually seemed to cast the shadows correctly, but as soon as I turned on more than one the artifacts would pop up. Very weird and frustrating!
I will do some experiments starting with a new scene and import my lights and Matte Objects one by one. Once I solve the issue I will post it here just in case someone else might have the same problem.
