Glitch in render ?

I have been rendering some particle based animation with simple lights however I am getting lines across the render, I thought it was at random as it only appears on the odd frames flickering but I am now wondering if it is an miss render and is a edge from the Cubes that is the particle emitter.

Its a little dark, but I hope you get the idea, its a black line across the grey background

Any ideas of possible fixes ?

looking at it when animating i think it is more a glitch as it moves across the screen, pretty much in the centre - its like tape drop out or something - have tried on mac pro and mac book so Its not a graphics card issue 2.47 & 2.46 same results.

It’s hard to tell something, not knowing what is actually expected to be seen.
And is there any geometry in this pic?
A blendfile would help perhaps?


im in production of making the film and so I do not want to release the blend file until after the event - its a little hard to explain though - there is nothing to see it should all be grey.
here is the line across the entire render there should be no line. there is no geometry only particles.

If there’s no object in front of the camera, this dark grey is a colour choosen in the Worldpanel.
Is there any texture mapped to the world?
And there are no particles in this frame, or I’m unable to see them.
The Emittermesh is outside this frame too?
So that’s really a shot in the dark.:slight_smile:
I would check the distance and limit values of camera, lights and shadows.
Applying dither to the render could be another try.

Sorry, this might be no help.


yes grey is from world panel.
no texture
the emitter mesh is in frame

Ill check distance and limits on camera, light and shadows and try dither too.

Hmm had a go at most settings did not seem to make much of a difference.
and I realised that my world panel in fact set to black its the lights that create the grey… hmm I adjusted quite a bit on the lights…

I just had another guess,
You’re rendering fields.
Usual when rendering fields, you will see artifacts (mouseteeth or combartifacts) on every first frame a particle appears, this looks quite different, but as I do not know how your particles look like, perhaps try it once progressive without fields.


this sounds like a good guess … I am firing a lot of particles off during a camera move…ok fields was off - so i turned it on seemed to make it worse - how do I do progressive ?

Could be a alising problem. Is that line at the place your emitter ends?
Try making the emitter visible and see if the line corresponds to an artifact produced by the emitter. Maybe it is castin shadows or something.
Also try the Full Sample Aliasing but be aware that this introduces extra time for compositing. Oh and Save Buffers must be activated for it.

Thanks - it seems random on the screen - one thing I have not tested is whether frame 1001 for example always has the ‘glitch’ line… then I can check if its the emitter doing something as well,

have found that it is a specific frames - no luck so far - have tried compositing nodes as well - cant see much when I turn on the emitter.

Have you tried rendering without a background using the “Key” setting then compositing the result over a still image of a background? That line is probably zero-alpha just like the world background so this would likekly solve your problem while reducing render time.

rendering with key has same problem - I think it is related to the halo light I am using as turning off halo and then render RGBA and pressing A in render (as I cant see anything with Halo off) I cant see then glitch where as all other times I can see the glitch

I have had a number of PM and email conversation with Patel in trying to fix my problems, we have not been able to resolve the issue, Patel gets it more than I do so here is a summary of the things tried and any other suggestions warmly welcomed.

Put the particle system and the spotlight in 2 renderlayers, or by putting the spotlight in an extra Layer and using the Layerbutton in the LampPanel. - did both

glitch is still viewable when pressing A with RGBA on

The textures are just cloud based textures

I think the Halos were not able to handle the doubled animation. Animated Camera on a path. Perhaps using only one , either the path or the keyed animation wouldn’t have made such trouble. - removed path

It was no more visible after the changes, but I only rendered about 100 frames (2000 to 2100)and the glitches just might have moved to another place
If not, it’ be wonderful.

In the moment I’ve isolated it to just one camera with 1 parented halospot .(No constraints, No path) And this reproduces the artifact with the camera animated just upwards very slowly. Nothing else, just a slow move in global Z
My sample has 400 frames and there were only 2 bad ones though.
Not animating the camera and animating the unparented spot alone upwards the z axis gives glitches as well.

I’ve just tried it, because I thought it could be a bug to be tracked.

Patel sorted it out ! Thanks again

I rotated both of your halospotlamps only about 2 degrees around the x axis by just grabbing their ROTX IPO upwards in y.
I’ve done this to make shure they are not pointing exactly vertical in the cameraview, in hope to avoid them drawing horicontal lines in the frames. (Possibly an interpolation issue)

Thanks to Patel & others - see for info on first screening

Nice to see your project is finished.

I’m looking forward to see the film (and hear the N:I:N)

GL, Pat