Hi all, I just found out one of the weaknesses of the compositor focal blur the other night. I have a scene of trees with the foreground being blured and the backround transparent with a backround image the glitch is that the blur works for the foreground tree bark but the edge of the tree outline is sharp against the backround - should be blurred. I cant use the old motion blur-focal hack because i need to use fullsample AA and that option vanishes when using fullAA any suggestions??
Wonder if you couldn’t use a Curves node to allow you to adjust the amount of blur as a non-linear function of z-distance from the camera.
I have done Non-linear focal blurring with a simple z-blur setup. Not sure it’ll work for you, but here’s the setup:
(You don’t need the alphaover node for the effect)
Thanks for the tip! I already figured out how to map the z and use as factor for the blurr node but hadn’t though of using a curve as well i’ll have to check this out
The only suggestion I can make is to use different layers for foreground and background blurring. The problem to be dealt with in this approach is the ‘halo’ the foreground blur can suffer from, fixed by additional blurring of both the image and the alpha. See the node setup.
I found that I had this effect (sharp edges that should be blurred) on near objects too.
Notice the chain in the foreground, extreme bottom right corner. It should be blurry (very blurry) but it is sharp. Look at the floor and you can see where the sharpness should start.
I used your above example after overlaying the scene on the backround and it works great. To achieve foreground and backround blurr you simply make the colorband go white-black-white or reverse and voila. I tried a RGB curve but didn’t work as well because trying to control the blur distances resulted in the curves going out of bounds and creating artifacts.