As some of you already might know, I’m working on my first little animation movie. Modeling and texturing were going fine and I really made some progress so I had a good eye on the project.
But when I recently made a test render of a car in the (unfinished) city, some black dots appeared on some places of the car (on reflective materials such as chrome,…). After searching through this forums, I thought it was a problem with the lamps I used for the headlights of the cars. Because they weren’t really necessairy I just deleted them but unfortunatelly the black dots were still there. I experimented with some other lights and enabled/disabled AO but I always get the black dots.
At this point I’m pretty sad because I realise that my whole project will fail if I can’t fix this problem. I hope that you guys can give me some advice or help. I just don’t know what to do.
You blender-pro’s are really my last hope.
To make clear what the problem is, I describe the scene here and post some screenshots & renders:
A little car is standing in front of some houses (which are part of a bigger village, which isn’t finished yet). A Sun is used and AO is turned on to brighten it al up a bit. I use the internal renderer because it’s fast and I like the result (except for the dots of course). I did one test with yafray and I didn’t get the dots but using yafray for the animation is not a real solution for me.
picture one: internal render (with black dots)
picture two: yafray render
picture three: the setup
Well, that problem is actually not that uncommon but sadly, sadly I can’t recall any solution which worked all the time. It rather seems to be a problem of the internal rendering engine - maybe the developers would be of more help than us?
Although I do hope that you get everything sorted out, eventually, it looks great…
sorry, I don’t really know the cause. It does remind me of some of the many issues I had when I wrote a simple raytracer.
anyways have you tried changing the octree resolution (scene buttons, next to and underneath the render button)? that technically should not change the correctness of a render, only memory use/time, but it may do something. with strange bugs you never know what might change behavior.
Can you post a .blend file at all? What OS are you on? And what build are you using, the official release? Or a custom one? Perhaps could you try a different one from graphicall.org and see if it make s a difference? I have an uninformed guess that it may be due to over-optimisation in the compiler when that Blender was built.
I can’t see what you are talking about - those images are too small to see anything other than the fact that you might need more samples in AO to improve the graininess.
Can you post a closeup crop?
Are you sure you haven’t accidentally duplicated the chrome objects so that you have 2 copies of the mesh on top of each other (I know its a basic question but it does catch us all out at some time or other).
I agree with Broken as I seem to remember this may have something to do with builds optimized for SSE2 & 3 chips. Posting a .blend may be the only way to get this solved. It seems that this is becoming quite common lately but I have never had this issue and I use ray traced reflections regularly on AMD Turion64 X2 under WindozeXP and Ubuntu64 Feisty.
I raised the octree resolution from 128 to 256, set AO to 16 with the distance to 4 and -especially for goosey ;)- made a bigger render but unfortunatelly the black dots are still there. :mad:
@PapaSmurf: if I don’t use AO, I need some other lamps and then I still get the problem. And actually I really like the result with AO on (except for the black dots of course).
@Broken: beside the fact I’m a kind of Blendernoob, I’m defenitely a computernoob. :o So I try my very best to answer your question as good as possible!
-I use an official version of Blender 2.44 (downloaded from the official site)
-My pc runs on Windows XP (home edition). some more info about it (don’t know whether it’s important or not): it’s a pentium 4 3.6GHz and I have a NVIDIA GeForce 6600
-I’ll try to post the .blend somewhere asap.
While trying to upload the .blend file somewhere I suddenly realised that the textures would be gone when some of you rendered it. Just out of curiosity I saved the file in a different map (so that Blender doesn’t find the textures) and rendered it again. I was very surprised to see that not only the textures but also the black dots were gone! It is still not a solution for my problem because I really want to use self-made textures but maybe it is important to understand the problem? I hope it helps.
ps: for my textures I use different kind of filetypes: jpg, png & psd. Png & psd are very useful for me because they support alpha.
pps: posting the .blendfile isn’t important now I guess?
Interesting…so you don’t have the problem when you remove your textures? Could it be that these textures are .psd files? As for me, I do have quicktime but I always avoid the .psd format since it sometimes gives weird results. Have you tried .png or .tga instead? Both should be able to replace the need for .psd files you use.
Not for any different features, but merely because it’s compiled with cygwin, which is a different system to the official builds. If it renders ok, it’ll give us some clues that it may be related to compiler optimisations.
@RamboBaby: Thanks for the tip about packing the file (never heard about that :o) but uploading the file on that site doesn’t work fine. Someone knows another site to upload files?
@Conz3D: I do have AO on and there’s a world texture but deleting the texture doesn’t solve the problem: the black dots are still there.
@Broken: As you suggested, I downloaded the file, unzipped it but when I try to run it then I get an error: the program can’t start up because ‘SDL.dll’ can’t be found.
Pfff, seems like nothing works fine for/with me… Or am I just a giant noob?
You should probably have an sdl.dll from your main blender installation. Copy the dlls from your blender folder to where the newly downloaded blender is - it should work then.
I installed that version and had to copy some files from the official Blender 2.44-map (also had to rename one file -> pthreadVC2.dll to pthreadGC2.dll) but it worked! No more black dots here
Very very interesting. My guess is that th edots are caused by some kind of compiler optimisation used to make the official build. I really don’t know that much about that kind of thing, but I’ll raise it on the main coders mailing list.
I’d like to add a big “Thank you” as well (especially @broken) since this topic comes up from time to time and I never had a proper solution or even a clue. Now there might be a chance that there is a real solution coming up.
Or am I just a giant noob? 
