Particle Problems...

[xynaria]

I think one thing for folks to know here is are the triangles showing due to failure of the opacity mapping on the edges of the triangles and if so would using instanced partiles where it might be feasible to do something about it help??? :)

[Brain_Donor]

:lightbulb

oops one thing i forgot to mention is that it only happens when it passes in front of some volume light..... with out the wolume light on its fine..... i think i have done the necessary exclusions ... but i may have missed something.... some hidden option i mean .. nothing obvious.....

[Toxie]

When you make a particle system with a material with an opacity map on it you should always make sure that materials specular level and glossiness are set to zero with the illumination set to 100 (optional) that should fix the problem :)
Attached below is a cloud of smoke I made with a standard 3d studio max particle emitter :)

[Chris]

If it is happening with Volume Fog it could be the 'fog not obeying opacity of objects bug'

I've done some cuttin & pastin from the discreet FAQ about this problem:

lots of renderers exhibit this phenomenon. It's because the fog is a z-buffer effect and doesn't take into account the alpha channel correctly. That's normal. The same phenomenon can be seen in MAX scanline, Mental Ray, PRMan, and BMRT.

Some possible solutions:

1) Activate "exponential" switch in the fog settings. This doesn't do anything but shift the problem into a smaller zone and, if you're really lucky, shift the problem outside the zone where your opacity mapped objects exist. It's a quick thing to try though.

2) (my favourite) Render a beauty pass with fog ON, and render a separate matte pass with fog OFF. Composite together using the matte pass as the new alpha channel.

3) For the most power, put your "fogging" in the material, as a falloff map, distance based. This is my favourite when time allows because it gives you control to fog different objects by different amounts, and excluding objects from fog is simple. Depending on how many different materials are involved, you could be in for a rather small or extremely large task. MAXscript might assist in automating this.

4) Some volume fog plugins by 3rd parties might be worth investigating. Results may vary and the rendering will probably be slower.

Martin G Foster

[Brain_Donor]

cheers for the advice guys.... ill try those things out and get back... :D

[Brain_Donor]

CHRIS youre a life saver........

the exponential on the volume light worked :)

thanks a lot man dont think i would ever have found that.......

now to render the blooody thing :P

[edaddy]

i might be a little late on this one : but oh well. . . . .. .

use 'facing' particles, make them 2-sided, opacity map them(radial) and make ALL of the colors darker, the whitest white in the middle should be grey, on the pic i saw posted on this thread the smoke looked way too thick, but everyone else pretty much solved it for ya -- ;)

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