This is a detail of two renderings both identical except that one has the "gamma correction" enabled at a value of 1.2. "Best" anti-aliasing was used for both.

Note the black specks all over fine detail in the lower one (gamma enabled)

(This image is jpeged for the post and has lost some quality)

Has anyone seen this before?

Thanks
Ed

1.) Nice render! 2.) Very bizarre. I normally don't do the gamma correction until post processing. Never even tried actually. This might be something to send to Eovia. -Kix

I've had black flecks like that in RDS, too. I've never figured out what caused it and have just tediously corrected them in Photoshop. Hmmm.... And I agree with Kix -- nice render! - Dex

Thanks for the compliment! I guess I'll send it on to Eovia... and stop using gamma correction:-) I'll post any info I get. Thanks Ed

Eovia said this is a bug that they are working on. I discovered that by increasing the shadow sensitivity to .5 I could improve the render. Thanks all Ed

i would also recommend doing the gamma correction in post. you'll just have far better control over it. that image is really looking nice. i love the detail in it. -pix

Maybe I should add that reason I was playing with gamma corrections is that the manual states: "The global illumination renderer performs more than a correction for the image when the gamma correction is turned on. It also makes sure the textures are correctly taken into account in the lighting process." Apparently this is not the case or not important? Ed

Well, I'm not sure I understand exactly what the "texture correction" entails, but I've done a few GI renders and haven't had any problems. Sometimes textures or lighting setups need to be tweaked here and there, but nothing has been noticably wrong.

Also, unless this is part of an animation, or there are other elements / lighting effects that you intend to show in your image, you really don't need to be using GI. I don't see anything in your image that couldn't be achieved by putting a spot beneath the scene set to not cast shadows, a couple spots outside the scene also w/ shadows off, and then adding a few bulb lights as needed around the space.

In fact, the underside of the microscope where the lenses protrude from is so dark, that it almost looks as if you're not using GI at all. So why take the hit in render time if you're not going to reap the benefits visually?

Just a thought. I don't mean to bust on you choice of execution or anything. There may be an element I'm not aware of that led you to this decision. OK, stepping off soap box now. : )

I still love the detail on the lenses.

-pix

Thanks for the comments but I did have a specific idea in mind I thought GI would be good for. That's why I bought C2 in the first place. However as you can see from the streaks in this test render it seems Carrara is unable to cope with global illumination. Eovia reports that this is yet another bug in the renderer which "they will fix in a future release". Yeah and charge me another few hundred dollars. I've sent them 2 bug reports in as many weeks they should be paying me. Quirky programs are the name of the game but if in the end you can't produce then it's all just a waste of time. Feeling peevish... ED