Well, 4 hours and no answer from C yahoogroups so I'll try here...

Often my soft shadows produce an block-shaped area where the shadow is lighter as in this image below. The settings used are included - there is one bulb in the scene set to softshadows with a radius of one.

Have I asked yet another unanswerable question? : ) I would think some of the C3 producers/advanced users would know this - perhaps none are around. (Yet I see them answering other questions... oh well)

My gut reaction is that you have found a chink in the shadow armor. Do you have the quality of the shadow set to it's highest level for the light source? I've had similar problems with the old soft shadows model which was in C2 but from what I can see here, you must be using the new raytraced soft shadows. If this is a spline model, it's possible you have some weird quirk in the cross section at this juncture. A previous post in this forum discussed this concerning a sword I had made. I never really understood it and never went back to investigate it. That's as close as I'm going to be able to get ya. -Kix

Thanks, Kixum. I think the quality is set high enough. Actually, it's set to excellent but there is a "Best" after that. Perhaps I'll try that and I'll adjust the pixel depth once more and see what I get. Thanks in the meantime.

I have noticed that the interpolation is on the default value, try to increase it, probably will work:-) TOXE

Actually, I'm pretty sure you've found one of two bugs in Indirect Light that are plaguing me. This problem is random, and it makes hideous dancing square artifacts in animations. I'm using the Mac version of C3 and I've found that increasing Photon Count above 2000 seems to make things worse. Are you on Mac or PC?

See if the problem goes away if you re-render with Indirect Light turned off.

BTW, the other bug I've found: glowing objects do not illuminate their surroundings. If I suspend a glowing sphere above a white plane, there is no illumination. Strangely, the photon map looks good. Even more strange, if the glowing sphere is placed near the intersetion of two perpendicular white planes (or any other objcects that would reflect light at each other), the planes illuminate each other with the invisible reflected light!

This image is looking down about 60 degrees over an upright plane with a 2" glowing sphere on the other side suspended a couple of inches above the floor plane. It illustrates a really bad instance of the random square problem. Also, all visible illumination is IL reflected from the upright onto the floor - take away the upright and nothing but the glowing sphere is visible.

If anyone else has time to try this, please let me know so I can say if this is a Mac-only problem when I send a bug report.

But if it's indirect lighting, doesn't that mean a source can't directly illuminate anything? Which you partially confirmed by turning it off.

I'm sorry, I was a little unclear - shouldn't have gone off-topic with my second bug!

Turning on Indirect Light should cause surrounding objects to be lit. The C3 manual, p. 554: "Without Global Illumination, the glow will only make the object brighter, but if you enable the Indirect Lighting option, a glowing object will act as a light source."

I did not turn off Indirect lighting. I removed an object (the upright) that the light could bounce off. The result was no illumination on the floor plane (bug #2). With the upright present, illumination shows up with the severe rectangular artifacts in my image (bug #1).

If you look at 3ddave44's problem image, the artifacts extend outside of the shadow region, which made me think this is the same as my bug #1 instead of a soft shadow problem.

BTW, changing Lighting Quality seemed to reduce but never eliminate bug #1.

Hi Folks,
I got the shadow artifact fixed. TOXE, you were in the right area, except that the interpolation should be decreased rather than increased. Douglas Alden Peterson answered me on the yahoogroup post.

So Ralphh, try your work with interpolation unchecked or decreased to 0%.

See? : )

Thanks, folks, for your help!
Dave

Thanks for passing along the tip, Dave. I looked up "Interpolation" in the manual, it is apparently a shortcut to reduce render time, so it makes sense that turning it off is helpful.

The artifacts are still there, but greatly reduced. The image above is of the worst out of 108 frames.The direct lighting in your scene is probably washing out what's left of the artifacts. My scene is a deliberate I-L torture test.

One more thing about these artifacts, they are VERY annoyingly random. Two successive renders of the same scene with exactly the same setting yield different illumination levels from I-L and may or may not contain visible artifacts. My animation's I-L still flickers like a fire, and the dance of the rectangles goes on.

I really admire what Carrara can do, but it's just THIS close to being perfect for what I have in mind... :-(

I had and got rid of it... I remember boosting the photon count to get rid of the blocks. But maybe it was the interpolation. Or just plain luck. Or all those other corners I looked in. It happens mostly with planes isn't it? The parts where no shadow interactions i,s are sometimes colored slightly lighter. So maybe it also has to do with the quality settings of the lights you use, when using the soft shadow option. The default is 'fast', which sounds not too good. I hate it when I solve a problem by changing too much parameters at a time, so I can't remember which did the magic thing. Or which combination.

Ralphh - those setting still show you at 50% precision of interpolation. In my post about the image that worked, I said that was turned off. I don't know if you tried that but do. The only thing is it actually slows down the render time to have the interpolation down or off. But in my case, it worked. Actually, I see now that you have it unchecked but I'm not convinced the % amount is still not being taken into consideration. That's why I also suggested have that % down to zero as well as the setting unchecked. I had caustics in another render still render though I had unchecked it. There was still a value (though greyed out) in the setting. So try turning the slider down to zero as well.

GOOD LUCK!
Dave

Dave, thanks, but moving the interpolation slider from 50 to 100 to 0 seems to not affect the rectangle problem if the box is unchecked.

I remember another post several weeks back, someone was complaining about their animation having gritty, jumpy I-L (in C2.1). Possibly related to what I'm seeing. Hope this is something Eovia is already working on.

On the plus side, with interpolation off increasing the photon count definitely helps the flickering I-L light level, so I'm very grateful for knowing about that.

Sorry for highjacking your thread! :-)