Fur shadow artifacts

[Mzigaib]

I have my fur applied to my character and the lighting and the look of the fur are ok for me, for this stage it has no animation the problem appears when I try to do a turntable and in some frames I see black spots, scratches(yes, weird) appearing and disappearing on my fur, its like in some frames my fur were messed in some small parts, My first guess was a shadow map resolution problem, I cranked up my shadows to 2000X2000 and 4X4 pixel samples and still the problem persists.

I am using Micropolygon render with 2 spots and one point light and also using depth map shadows like I said, the rest of the settings are pretty much as the default.

For the turntable I used 2 takes to render, one just to generate the shadow map.

I would post the render but it's from work so I can't.

I'll try to replicate the problem but for now if anyone has any tip about how to find the problem I would really appreciate, I really need a help with this one.

Thanks.

Edited February 16, 2011 by Mzigaib

[Mzigaib]

Update:

I just notice that is not the hole fur, after I did increase the shadow map resolution I am just having problems in this case just in the head and I did notice that if I try to render the same frame with the problem again, sometimes the problem doesn't happen at all.

I am also using a farm to render.

I'll try to increase the resolution again but still any tip would be very welcome.

Thanks.

Edited February 16, 2011 by Mzigaib

[Mzigaib]

Update:

It's not a shadow problem, because I can see the spots through my color and diffuse passes, those spots are like holes on the fur and if I render the same frame again the holes appear in different locations.

Any tips?

[yongbin]

if you use catmull-rom(or the other) filter, try use gaussian.

[Mzigaib]

Thanks for the feedback, I'll try that.

I'm attaching four frames of the region that I am having the problem, if you load on Mplay and play it at 1 fps you can see the problem.

They're rendered in the same frame one after another, each render shows different spots in different places, I am just having this problem in the head the only thing I can tell is that it's the piece that has more polygons.

If anyone has any idea of what possibly could cause this issue please share.

Thanks.

fur_spots.rar

Edited February 18, 2011 by Mzigaib

[Mzigaib]

Update:

It's not a pixel filter problem, because I tested and the issue remains.

And it seems to be a issue that appears only in distance if I render closely on the face I don't see the problem.

I just don't know what I could adjust to make the problem go away.

Edited February 18, 2011 by Mzigaib

[Mzigaib]

Update:

I've increased the samples to 16X16 and rendered at 1920X1080 and I am still having the same issue, I've render some frames and I am attaching the Quicktime with turntable to illustrate my problem, is focused on the part that is happening the issue, you can jump frame by frame to see it better.

I would thank if anyone could take a look at.

Thanks.

fur_spots2.rar

[Mzigaib]

Update:

Now I am having problems on render, I am getting the error:

UT_NetPacket::read: No such file or directory

Anyone knows what could cause this?

Update:

I think I got to solve this modifying the resolution of the shadow map, I was having problem with 1000X1000 if I set this to 1024X1024 it doesn't give an error, weird right?

Edited February 23, 2011 by Mzigaib

[Mzigaib]

Anyway I am still having problems in certain regions of my fur, maybe it has to do with the way that I am trying to do the turntable.

My character is not rigged, I was hopping that I could get to do the turntable by just rotating the source skin node, it kind of works but the direction of the fur doesn't update as it rotates, so I had to hack the guide node inside the fur asset and reorient my fur direction attribute, it works fine for the rotate but I am certain that it must be a better way to do it without hacking the fur asset.

Said that I am still having problems with the areas where the fur is more dense, the holes on the fur are still appearing, I am hopping that someone could help me with this, starting maybe for a better way to just rotate my character to do a turntable without hacking the fur asset.

Thanks.

[Marc]

Hey

I just took a look at your render and I was going to say pretty much what you seem to have figured out. I can't remember the exact solution, but if you don't groom your fur in the right place then it won't stick/rotate with your skin. So without seeing your file it's possible that you setup the fur incorrectly and it's doing weird things. I've seen it a lot .

Since you can't post your file here I highly recommend sending it to SESI to ask them for help. They'd quickly be able to identify the problem and tell you what to do to fix it.

Sorry I couldn't be more help.

M

[Mzigaib]

Hey

I just took a look at your render and I was going to say pretty much what you seem to have figured out. I can't remember the exact solution, but if you don't groom your fur in the right place then it won't stick/rotate with your skin. So without seeing your file it's possible that you setup the fur incorrectly and it's doing weird things. I've seen it a lot .

Since you can't post your file here I highly recommend sending it to SESI to ask them for help. They'd quickly be able to identify the problem and tell you what to do to fix it.

Sorry I couldn't be more help.

M

Thanks you for the help Marc!

I'll try a little more before go to the SESI guys, but I've figured it out the turn table stuff, I was rotating the skin geometry without rigging the character, I also forgot to tell that I am newbie on the fur stuff, said that I've learned that the best way to rotate you fur is rigging the skin and rotate the bones, in my case a simple turn table I used a single bone, which worked fine. Now I am left with the spots problem.

I will be working a little more to try to solve this problem, any more tips would be welcome.

Anyway thanks for the help.

Edited February 28, 2011 by Mzigaib

[Mzigaib]

It seems that my spot problems just happen when my character is still on the turn table, I am not saying that I solved the problem I am saying when it has movement the spots are not appearing, which is good news.

Now I am having a motion blur issue, if I turn motion blur on the render time increases a lot, I am using micropolygon to render with depth map shadows. Is it normal that the render time increases this much with motion blur on?

Thanks.

Edited February 28, 2011 by Mzigaib

[Marc]

How much is too much? Motion blur should increase the render times, but not to ridiculous amounts.

M

[Mzigaib]

More than doubles the time, with the motion blur geo and xform samples to 2.

[Mzigaib]

Update:

Using deformation blur really increases a lot render time, I am trying to use geometry instead but I didn't got it to work yet, Any tips?

Update:

I couldn't make the fur work with geometry blur, I don't know what I can possibly doing wrong.

Anyway any tips regarding motion blur would be nice.

Edited March 10, 2011 by Mzigaib

[Mzigaib]

Anyone knows how to make geometry blur work with fur?

Edited March 11, 2011 by Mzigaib

[Mzigaib]

Anyone knows if the Dicing/Shading Quality should work on fur? I am trying to increase this value but it seems nothing is happening.