Shake and Z Depth

[joojaa]

well it depends on the footage, you do undertand that a antialiased zdepth does not produce andy significant advantage here. You could blur the borders for this effect anyway piror to blurring. Aloso the alpha can teake care of this if it happens to be suitable.

Im not realy a comp guy tough so my solution is not probably production ready.

some additional tought tough.

Sometimes its worthwhile to render out a seperarate double sized z buffer. it might sound like overkill but zbuffers render out pretty fast, because tehy are optimized for speed (after all dmap shadows are just zbuffers). On the same lines if you use a sampler like mr where you can get a double sized frame for about teh same calc time as a single sized since you can drop smapling one notch, and then resample down. I rarely do this offcourse becaus eit does not provide any additional benifit.

To tell the truuth the only real way to GET a realy realy good zblur is to do it inside your 3d app at rendertime.

[user_deleted]

It the same but you can easily pre process your alpha then...

do it inside your 3d app at rendertime
yes if no compositing required
or use layers+z (that's what i do and i didn't meet your problem i think most real productions with z do this) if you need to comp
Also your defocus filter is very strong

[user_deleted]

when you say use layers+z, what do you mean? do you mean render out in layers, use a zdefocus (or Idefocus and zslice) on each layer and then composite?

The defocus is strong to illusrate the edge artifacts. The image is obviously not from a production sequence but simply some test footage which we play around with.

[user_deleted]

do you mean render out in layers, use a zdefocus (or
Idefocus and zslice) on each layer and then composite?
Well as i said before i render out layers then use zCompose first and I use zSlice + filtering at the bottom of the z compositing tree (just before adding real shoot elements with inside/outside to limit the alpha)
The tuning with z channel is:
a subtile balance between
a - the amout of filtering (not too strong)
b - the contrast of control image alpha (that's why i prefer zslice and i NEVER use zblur or zDefocus except for real easy case)

Your problem is high contrasted Z + high defocus which make it unreal (even if the aliasing artifact didn't appear the sharpness of borders on defocused elements would be strange)

Yours

[joojaa]

Actualy whan you said 3d blur is of no use if you ccomp youd be wrong. Se what if the background layer has fov assigned for it in rendertime since ist realy the only one that can do truly pristine blur. And background plates are often separate. NOw what you do is apply zblur on the individual elemants that matches this blur NOW it blurs fine because you have a alpha edge you can use to fix the problem (this is described in the coocnbook that comes with shake).

Anyway. the edges of z CAN be blurred to remove the artifacts. As can finding edges on hard z depthhs and iplur those areas only.

[user_deleted]

I agree Joojaa,

thanks for the complement of info. So now we can say it's possible to get hyper realistic z based defocus in every situations