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Strange opacity behaviour when rendering paths

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Tim BentleyStrange opacity behaviour when rendering paths
by on May 8, 2012 at 11:12:10 pm

I hope someone can spare a moment to take a look at this weird problem - I've searched everywhere for 4 hours :-(

The movement across the map is done using a camera, and all layers are 3D. The 'links' are done very simply with trim paths and a glow filter - although they are 3D, they all sit at 0 on the z-axis. The strange thing is, it looks fine in the comp window and ram previews beautifully - plus, it wasn't doing it until fairly recently, when I added a lot more 'links'.
I'm fairly experienced with After Effects and I'm CERTAIN I've tried everything obvious - OpenGL is off, multi-frame off etc. and there doesn't seem any explanation why these 'links' are at full opacity (as they should be throughout) until the camera moves, then they all kind of 'strain' into translucency before going back to opaque when the camera doesn't move.

It's very far from finished, but I can't start adding all the other elements until this is sorted.

Huge thank you in advance!

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Dan FredleyRe: Strange opacity behaviour when rendering paths
by on May 9, 2012 at 4:51:00 am

A. Try taking the glow off (Try using a duplicated fast blur layer instead)
B. Try bringing the links to -.5 in Z space

Dan Fredley

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Tim BentleyRe: Strange opacity behaviour when rendering paths
by on May 9, 2012 at 9:17:44 am

Thank you very much for your reply Dan,

The glow doesn't affect this issue - I'd already tried.

Your suggestion works for the z-axis. In fact, I had already tried moving each one -1 further along than the previous, but after the 18th layer, it was -18 along the axis and practically in line with the camera, causing lots of problems. Stupidly, I didn't think of moving them all up together by a small increment.

Having said that, I find this odd. If this is the only fix, it seems counter-intuitive. Maybe I spend too much time in Photoshop, but to me the layer order on the Comp should be telling After Effects where each layer sits in relation to the next, especially where you have lots of layers on the same point in the z-axis. Is this not the case? Do I need to budge things a tiny bit backwards or forwards so it's clear which one is above or below the next?

Anyway, hopefully that's solved the problem, and thanks again for your reply. I'd be curious to know why, although I have close to 60 'link' layers, it's OK for them to sit on the same z position, but not the single base layer beneath?!


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Dan FredleyRe: Strange opacity behaviour when rendering paths
by on May 9, 2012 at 9:26:51 am

Occasionally I run into this issue, but unfortunately I have no explanation why it happens--by all means your layer logic is correct, it just seems AE gets confused when two layers occupy the same space. Another solution would be to just add a 2D adjustment layer between the base layer and the link layers to give a definite barrier so they never cross. But it depends on how much interaction you need between layers.

I'm not sure if the close proximity of the camera affects it either. Maybe try putting a camera way back and zoom in just to see if you have the same issues. Working in microspace in AE is never fun, but it seems every client wants us to zoom way out then zoom way in.

Dan Fredley

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Tim BentleyRe: Strange opacity behaviour when rendering paths
by on May 9, 2012 at 9:48:12 am

How fantastic - your adjustment layer suggestion seems to work as well (and I prefer it as a workaround, it's somehow 'cleaner')! I can sort of understand why this happens - like you say, thanks to the client, I've had to work in microspace (the camera lens is practically touching the sodding map) so it doesn't seem surprising that after effects is trying to 'place' the layers in 3D space, and in doing so is overriding the layer ordering in the comp itself.

Also, bringing the camera way back helps, although there's still a bit of hesitant opacity jigging about. It's funny really, because there must be some kind of 'conflict' going on in terms of AE's render engine, and I like that its conclusion is 'Well, he probably wants it flickering around like his video is having a stroke.' :-)

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Darby EdelenRe: Strange opacity behaviour when rendering paths
by on May 10, 2012 at 3:41:02 pm

Do the layers have motion blur enabled? AE tends to do this sort of thing when layers share the same z-space, and will almost certainly do it if they have motion blur enabled.

Darby Edelen

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