dirty alpha channel...

[apoc519]

did you turn the reflectivity to 0 and specular to black on the use background shader? Thats fixed the problem for me before

[mandark1011]

looks like the surface has cast and recieve shadows turned on.
if your only looking for a clean dust pass you should turn render stats off except for primary vis and smooth shading

[apoc519]

but you'd want the ground plane to receive shadows, no? Just not cast them

[mandark1011]

depends if your looking for a "clean" alpha for just the particles or a particle and shadow pass for them, either way it does look like a render stats issue i believe

[thomwickes]

Yeah, sorry - not entirely clean - i'd like the shadows in there too. I'm pretty sure i turned off 'cast shadows' but i didn't turn the reflectivity to 0 and specular to black on the use background shader. I just stuck it on and hoped for the best.

I'm not at home right now but I have a few things to try when I get back.

Thanks!

[thomwickes]

done - it was the render stats thing, but still usefull to know about the reflectivity/specular thing.

Thanks

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