Render Problem- Strange artifacts showing up on final render

[cindylyoung]

This model has rendered fine in the past. Now certain patches do not render in some frames, creating a flickering effect. I've uploaded a .mov file so you can see what's happening. I've also uploaded an image that I rendered previously. You can see that it rendered fine. I've been using A:M for years and this is the first time I've seen this happen.

Any insight is much appreciated.

 

Thanks

[robcat2075]

I've uploaded a .mov file so you can see what's happening.

 

the mov is only 91 bytes and won't play. Try uploading again.

 

 

however, are you using a different version of A:M than before?

[Gerry]

Hi cindylyoung - Tried to look at your .mov in three different browsers and just got a white "?". Can you upload a different version of the .mov?

 

If this QT is a render right out of A:M you might try exporting it out of QT to a new .mov.

 

Gerry

[cindylyoung]

Oops. Grabbed the wrong file. That one wasn't self-contained

 

Robcat2075, your questions is a good one. I upgraded to 15.03 recently, probably after I did the render that worked. Not sure exactly when. If that's the problem, do you have any idea how to fix it?

punctalPlugSmall2.mov

[robcat2075]

Nice eyelashes!

 

That does look odd. It's like you've caught A:M subdividing its patches.

 

Is there any chance there are duplicate or internal patches at those black spots? I'm just wild guessing here.

 

 

 

Does this happen from any camera angle at any distance and any lighting? Or just this case?

 

If you remove the decals or turn off hair does that change anything? Is there a material on that skin? if you remove that what happens.

 

I'm just thinking that some small change might give someone a clue.

 

 

What was your previous version? Can you reinstall it?

 

If you can load this into two different versions of A:M and get different results that would be something to report to AMReports with renders from each.

[Rodney]

Cindy,

First things first... other than the artifacting... that is one very nice render (the modeling, the animation/camera work etc)!

 

It'd be nice to see a wireframe or shaded wireframe rendering as that'd show us where the patches are.

I think we can guess by the artificating however.

 

Its it possible that you've got the older porcelain material on the model? (any materials applied to that area for that matter?)

If yes, if you take the material off will the artifacting go away?

 

I ask as several years ago A:M changed how porcelain materials work.

 

Also... don't hit me here... silly question that has to be asked:

Did you check your normals?

[Paul Forwood]

Are you using SSS on her face?

[Master chief]

i know that when i get something like this it usually means its caused by a double line ie two identical lines on the same spot connected to the same area , may have been caused during upgrade,

 

my 3 cents

[alano]

This looks similar to a problem I'm having with decals on v15. The decal somehow spreads to nearby patches and leaves solid color patch-like artifacts. Support has been no help and I'm still at a loss. Do you have an old copy of the model without decals to render with the new version?

 

Alan

[cindylyoung]

I'd be really surprised if there were any internal patches, but I'll check to be sure. Will check normals. (I would have had to have done something really goofy)

There is no material on the skin, and the only surface attribute I've set is is diffuse color. I've got a decal for the eyebrows of course.

I'll try rendering from a different camera. I did move this camera and the problem didn't go away

I'll also try turning off hair, removing decals.

Sorry, haven't got a clue what SSS is.

 

Will post some results later today

 

(P.S. Thanks for the nice feedback on the render).

[robcat2075]

This looks similar to a problem I'm having with decals on v15. The decal somehow spreads to nearby patches and leaves solid color patch-like artifacts. Support has been no help and I'm still at a loss. Do you have an old copy of the model without decals to render with the new version?

 

Alan

 

This is jogging my memory about something I ran into between v10.5 and V11.

 

it seems with V11 a decal with an alpha channel or transparency needed to completely cover any patch it came into contact with or the patch would go transparent. They didn't flicker though.

 

The solution was to first hide all but the patches the decal would be visible on and make sure the decal was bigger than that area. Then apply.

 

try a render with the decals removed as a first test. and if that gets rid of the flicker try remaking your decals as above.

[cindylyoung]

It seems that the problem has something to do with the decal. When I remove the eyebrow decal it renders fine. I've opened the decal art in Photoshop and made sure the the edges are really nice and clean (no almost transparent pixels scattered about) and reapplied the decal and although it isn't as bad, the problem is still there. The decal is a 24-bit PNG. A different camera/position made no difference.

 

Robcat-I encountered that problem with the eyelashes initially. The decal transparency area didn't cover the entire eyelash model so there was a corner that was not transparent. I solved that the way you suggested. This is different. I made my eyebrow decal with lots of canvas around it so I could extend the decal beyond the area I had selected to apply it to. But now that I've done that the artifacts are showing up right near the eyebrows. That's why I thought It might have something to do with almost transparent pixels.

 

There are no double splines (I've done that before so I know what that looks like)

punctalPlug_Camera2.mov

[HomeSlice]

Maybe you can try converting the PNG decal to a TGA with alpha channel and see if that fixes it?

[robcat2075]

Just to make sure I'm explaining my idea clearly....

 

suppose you have a decal that makes a blue cross on the mesh like in this picture:

 

 

 

a bitmap like the orange rectangle that just barely contains the cross would cause my disappearing patch problem.

 

a bitmap like the green rectangle that completely overlaps all patches that the blue cross contacts, and was applied with all the patches marked with a red X hidden, solved my problem.

 

You may have done this already, but I wasn't sure from your description.

 

Anyway, finding that this is decal-related is progress!

[Master chief]

id suggest that just to test and see if its just the decal / patch's , you move the decal to a random place on the face and render , may look silly but if every thing renders correctly then its the location , if not its the decal itself.

 

also you might want to post the model so that some of are more experty users (robcat) can take a look , if for reason that we don't need to know about you cant simple say that.

[cindylyoung]

Hi Robert, yup that's what I did. See attached screen shot.

 

I also tried saving the PNG as a TGA with an alpha channel and the results are no better.

[cindylyoung]

Further to other suggestions:

•put the decal somewhere else on the face and the patches surrounded the decal

•put the decal on the old flour sack and the patches appeared there as well

 

So it seems it is the decal in regardless of whether it is PNG or TIF. Note that I'm using a PNG transparency map on the eyelashes they are working fine.

 

I'm attaching the various decals I've tried.

[robcat2075]

Hi Robert, yup that's what I did. See attached screen shot.

 

I also tried saving the PNG as a TGA with an alpha channel and the results are no better.

 

Just to try... respline that eyebrow area so the decal isn't hitting any five-point patches. It shouldn't matter, but....

[largento]

You know, looking at your video render, I was reminded of an issue I ran into last year.

 

I had taken a model I created using the Mac version of A:M and brought it into the Windows version to animate and when I rendered it, random patches would disappear from frame to frame.

 

At the time, the only think I could think was that it had something to do with the porcelain material, but I never did figure out what was causing it.

[alano]

I have some new information though I'm not sure what it means. I created a single 4-patch and added a decal with transparency that has given me trouble: Sample 1. I then deleted the decal, added one over the whole patch (no transparency) which rendered as expected. I then added my transparency decal and it also worked as expected: Sample 2.

 

sample1.mov sample2.mov

 

I'm confused.

 

Alan

[cindylyoung]

OK. I tried what you suggested Alan but it made no difference. (I applied a decal without transparency, then deleted it and applied decal with transparency.)

I finally resorted to creating my decal with a background with the same RGB values of my surface. I applied it and I am relieved to say that you can't see where the patch ends. This is a work-around and certainly is not ideal but it works in this case. I can't think of anything else to try.

punctalPlug_snippet.mov

[robcat2075]

OK. I tried what you suggested Alan but it made no difference. (I applied a decal without transparency, then deleted it and applied decal with transparency.)

I finally resorted to creating my decal with a background with the same RGB values of my surface. I applied it and I am relieved to say that you can't see where the patch ends. This is a work-around and certainly is not ideal but it works in this case. I can't think of anything else to try.

 

You should make an AMReport of this, showing the different results you get with different versions of A:M.