[Josephus Holt]

I've searched the posts concerning this problem but don't find any particular solution to try...seems very scene-dependent. I'm modeling in Rhino and exporting via dxf to C4D using the Maxwell plugin (latest) there to render out. I tried eliminating a particular MXM that I thought might be the problem (there are actually very few materials assigned at this point...just mostly lights), and although it seemed to reduce the amount of black spots, it did not eliminate them (it was a modified AGS glass).

I have not used any SSS....will try now to run with all AGS eliminated to see what happens. Just have no idea if the problem is with the geometry, normals, or materials at this point. I have been seeing that exporting Rhino geometry into C4D gives me some unexpected normals at times.

I've made mention of running into this problem in another post but as no suggestions for help were forthcoming, thought I would try a more direct approach here.

This is my first serious work to get a top quality render with Maxwell and after having worked so long/hard this is really quite discouraging.

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[Mihai]

Did you try removing the coating component from the lamp shades?

[Josephus Holt]

yes...removed the coating component, made no difference.

Am running another one at this moment with all AGS off...so far at SL14 I'm not seeing any black dots.

I'll try running another version with an AGS created with the wizard...just not sure which AGS I used, but I think it's one I either downloaded from the MXM site or was in the library.

update at SL 15.31...seeing four black dots now

[Mihai]

Did you change anything to your emitter geometry? Do any of them have long irregular triangles?

[Josephus Holt]

I'll need to wait until I'm done with this render to check....kind of hard to do with Maxwell running, even on this machine.

UPDATE: I checked the emitters, and there are a number of them which were triangulated with one very short leg and two very long legs....most of the undercounter accent lights have this issue. I will triangulate them in a more regular pattern and see what effect that has....will run it overnight and let you know in the morning how it went.

[yolk]

i like the image..just photoshop some semitransparent wings on the black dots and the image will be perfect

[Bubbaloo]

I noticed you mention the dxf format. When you import into c4d does it have welding options? I'm still standing by the black dot problem being an SSS component in there somewhere... Did you pull any materials from the mxm site that might have SSS? Anyway, if there is SSS and the dxf model is not properly welded, it will result in non-closed meshes that cause these black dots when SSS is used...

Maybe try welding vertices in your scene anyway?

[Josephus Holt]

i like the image..just photoshop some semitransparent wings on the black dots and the image will be perfect

I'm afraid that would be no yolk with my client

Bubbaloo, thank you much for your suggestion....since I want to find out the root of the problem, I'll go with Mihai's suggestion first and get the emitter triangles to be more "regular". I did not have this problem at first, and I keep merging the Rhino-generated dxf files every iteration....it might be some of the emitter geometry I created in Rhino. If that doesn't get it, then I"ll look at welding vertices as you suggest....but I really don't have any SSS in there at this time.

[Josephus Holt]

I'm not sure if this was the right way to do it, but the emitters that had the very irregular triangles I made as Cinema4D N-gons...not sure if that fixes that problem or not. I'm running another view and at SL11 already am seeing two dots

I'll let this one run a while and see where it goes. If it gets too "dottie", I'll redo the emitters that seemed to be a problem...will use simpler geometry.

If I'm still seeing specs in the morning I guess that I'll have to do some welding

[Bubbaloo]

N-GONs for emitters are a definite no-no! There was a test posted a while ago comparing n-gons to triangles as emitters and the results with the n-gons were very bad. Sorry can't find the old topic.
(I still say it's SSS)

[Josephus Holt]

I'll take your word for the Ngons, although turning them off during this render did not remove the dots, which are fewer by the way.

So if I have a very long linear light...let's say 96 inches by 4", what is the best geometry for that?

Hope I find out soon what is causing this...the time to search it out is killing me.

[JDHill]

Maybe a silly question, but can you explain a little bit on why you are moving this over to Cinema? Do you still see the issue if you use the Rhino plugin to render? What I'm driving at is this: is the Rhino > DXF > Cinema path introducing something that's causing the issue, or is it already present when you're still in Rhino?

[arch3990]

I only had the problem with these black dots when I overclocked my dual Opteron 885 from 2.60 GHz to 3.00 GHz. If you wanted to overclock on this Platform you had to raise the FSB (Memory) with "clockgen".

The overclocked system went stable with all sorts of benchmarks, etc. But in Maxwell these black dots appeared.

Perhaps there might be a problem with memory or memory settings.

[kami]

the problem is getting more and more interesting when hardware reasons come into consideration as well

but I have the same question as JD: why do you export from rhino into c4d? It's a work step more and you a potential source for errors ...

or if you cannot avoid it: try exporting as .obj and see if it differs ...

you could split that very long light into 4 pieces (mesh-wise) which gives you 8 triangles per surface.

[Matthias Rudolph]

in C4D you can use the function "optimize" under functions.
1. switch so vertex mode, select all your verticies
2. go to functions and select "optimize". The optimize functions deletes unused points and also welds points within a specified tolerance! use this function..if 0.01 doesnt help, try 0.1 or so..