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Otterman
12-10-2015, 03:26 AM
Hi fellow wavers

I have come across this issue where the edge of the geometry when against a background renders with really rubbish aa's.

It is essentially a HDR lighting rig so the backplate is rendered (no geometry) = edge with geometry is screwed up anti alias

but the shadow catcher (geometry) = edge with other geometry antialias is good.

Im using ExTrader, working in linear workspace and rendering in 32bit with multiple render passes. The majority of them seem fine but Z space, Radiosity (attached) for example are screwed. Weirdly the alpha is also screwed but converting it to 8bit fixes it. This does not fix the others though.


Anyone else come across this and know how to fix it? I know I can fix it by placing geometry behind the subject matter I want to avoid this.

omichon
12-10-2015, 05:35 AM
Could it be a Premultiply / Unpremultiply Alpha issue ?
Just a thought.

lardbros
12-10-2015, 08:37 AM
Could it be a Premultiply / Unpremultiply Alpha issue ?
Just a thought.

I was thinking the same, especially as the alpha looks fine. Try turning off Unpremultiply Alpha on the output settings.

If you load both the image, and the alpha into Photoshop, and then take the main RGB pass and make a mask using the alpha... i'm sure the nasty edges would disappear.

Otterman
12-10-2015, 09:35 AM
hum within Lightwave settings alpha was set to Premultiply and 32bit. Extruder is a different animal though and has different settings. I will look into this and experiment. Thanks guys