How can I get rid of these artifacts. This pixilation unwanted effect only shows up on this part of my render. It's the only portion that actually uses "light through transparency." I brought up the photon count and I do have interpolation checked. What setting can I move to avoid this.

Now it's time to start carefully, slowly increasing a couple of other settings: Photon Map Accuracy (PMA) and Lighting Quality - both found just a little further down the list in the GI portion of the Render Room. PMA will help even out the increased photon count and create better distribution. Play with the PMA setting a bit before adjusting anything else. I suspect bumping this up to 20 or 30 percent may fix the issue. Changing the Lighting Quality setting will also help but you can't control it with as much detail. However, it is usually part of a good solution to the issue you have here. Just remember to adjust only one parameter at a time so you know which change is helping you get closer to your goal. ;) Mark

Thanks Mark. My PMA is a 31% and the Lighting Quality is at Best. I guess I will increase the PMA to 40%? The interpolation setting is at 57%. Dose this have any bering with this issue?

uncheck interpolation (no interpolation).

Interpolation allows Carrara to guess at photon placement - the lower the precision setting, the more Carrara guesses. The payoff if faster render times. Miss Nancy's advice is good if you are doing a single image. However, if you're working with an animation, you may want to try settings between 85 and 100 percent on the interpolation slider because of time per frame on render. 100 percent precision IS different than the No Interpolation option you get when selecting the check box. The 100 percent accuracy will still provide faster results than those you get when simply unchecking the interpolation option. Additionally, one possible assist that I forgot to mention was to turn on the Improved Edges option. Sometimes this will help when using transparency and sometimes it does nothing at all. I've worked on several assignments very similar to what you show in your preview image. There is not a single "bullet-proof" method of fixing the issue because of other variables. The biggest variable is what is doing the GI lighting. If you are only using lights, it's much easier. If you're using an HDRI or Background map, things can get a little more complicated. Mark

Thanks, both but I added a pretty complex shader to the render and I am really taxing my systems. One single "Sun" light and one spot. I turned interpolation off and things are crawling big time. I have a G5 dual 2.3 and a MacBook 2.0 dual core crunching at it at the time. I will probably let it render over night and see how things turn out. I am still using Carrara 5 Pro, any improvement on render times with Carrara 6? Is the upgrade worth it? I am pondering whether to get it nor not.

Great job.

At the current deal, the update price to C6 is a bargain to good to miss. C6 is as good an upgrade as C5 was from C4.

If you are using HRDI and Sky Lighting, sometimes turning off Interpolation is all you can do.

yep, it's gonna be slow. there are several other settings one can cut down on (with interp. off) to speed it up. see mark's 1st post above.

You can also look into Pixel Accuracy, sometimes that affects the blotchiness. Another option I have used is to group everything together except the glass or transparent objects. Group those objects in their own group. Save the scene, then save it under a different name. Go to the original scene and turn the visibility off for the transparent group. Turn off the transparency options for GI and render it, it should be much faster and easier to control the blotchiness. Save that image. Now, in the other scene, make the other group not visible. You really dont even need GI at this point, take the image from before and use it as a backdrop. Then render. In your scene this might work. But in some scenes, the reflections that you want on the glass would be gone. That is where options such as unseen by camera but still seen in reflections helps, but Carrara lacks that option at the moment. The only time I use transparency with GI is when I need some caustics from the transparent object, otherwise I dont use it, if I can get away with it. Either way, if you want to troubleshoot the blotchiness, I would first make the transparent objects not visible. Then render. You might have a very clean image at this point. If not I would adjust the settings without the transparent objects to get it clean. Once clean without the transparent objects, you have found the minimum settings. Once you add the transparent objects back in and checked light through transparency you might have some more blotchiness, just keep at it. I have found that scenes with transparency can take forever to troubleshoot until you establish the minimum quality settings needed without transparency as a baseline. From there it is often easier. Another thing to consider. It may not apply to this scene, but for interior shots I have had much better luck by using a photon emitter as opposed to a real light. A photon emitter is just an object that has a value or color in the glow channel. Most of the time you will have to use the multipy option with a color. Say pure white with the 0-1000 scale. Doing it this way I have found that blotchiness is less of a problem than relying on a bulb, distant or even spotlight. You also get very soft shadows this way. I will usually place the object outside a window, then it will cast "photons" or light into the scene. The GI (photon mapping) handles the bounced light after this point. Finally, often times ambient occlusion is enough to sell a shot, especially a product shot. The SkyLight option as well is often enough. But when I need full blown GI, personally, I have had better luck using a photon emitter. It really depends if you have the time or not, especially if it is for a client. In a production environment, GI is often too slow, which is why it is generally faked, with Ambient Occlusion and good texturing. Every scene is different though. HTH Donnie