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piRoN
05-05-2014, 08:28 PM
Hi folks, long-time Lightwave user, first time help-requester.

Doing a bit of spacey stuff for a film at the moment, and I've come across a bit of a vexing bug that's doing my head in. While I was putting together some atmospheric effects for my Saturn scenes, I noticed I was suddenly getting a sort of embossed edge on the rings, even though the surface is supposed to be 100% transparent at the edges of the geometry. After a lot of dicking around troubleshooting, I managed to track it down to some sort of weird behaviour between the volumetric lighting and the transparency of the ring material. To illustrate, I've replaced the rings' transparency map with just a flat black map to highlight the problem - obviously the rings should be totally invisible here because the surface is fully transparent:

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When rendering, in the initial radiosity pass the rings show up as a hole in the volumetric lighting, which is fine, but it seems almost like the subsequent rendering isn't matching up the edges of where it's drawing in that part of the image. If that makes sense. Playing with the antialiasing settings can minimise the effect slightly, but there's always an ugly, weirdly aliased line where the edge of the ring geometry sits.

Geometry-wise, the ring is a single-sided affair with a double-sided surface on it, so there are no real edges there.

Any ideas?

djwaterman
05-05-2014, 11:12 PM
I really don't know but have you tried making the rings a two sided solid rather than a zero thickness single sided polygon.

Also, I'm not sure there would be any volumetrics happening around Saturn.

piRoN
05-06-2014, 12:09 AM
I really don't know but have you tried making the rings a two sided solid rather than a zero thickness single sided polygon.

Yeah, I tried a couple of variations on that theme when I was troubleshooting, but the problem seems to be purely in how Lightwave is rendering the volumetrics.


Also, I'm not sure there would be any volumetrics happening around Saturn.

Yep, there's some heavy artistic license here - these scenes are serving a more poetic role in the film, so realism has to take a back seat. Lots of nebulae, dustclouds, beams of light, and additional psychedelia that mirror the narrative direction of the main plotline.

gerardstrada
05-06-2014, 02:11 AM
Any ideas?
Looks like you need to enable Volumetric Antialiasing.



Gerardo

piRoN
05-06-2014, 07:19 PM
Looks like you need to enable Volumetric Antialiasing.

Ding ding! We have a winner! Thanks mate.

Took me a while to find that option - it seems like it would make much more sense to put it in the render panel with the rest of the AA settings.