Well after the first full render I have been looking through ways to improve it. I also noticed a z-mask problem of which I posted about on this forum. The solution given back worked fairly well except for the first part of the scene when the butterfly is in the grass: something weird is happening where the final composite is just the grass with a black background – no sky, no butterfly. I also think that the blur on the butterfly (even though the depth of field is supposed to be tracking it) is a bit too much. So I have several options:
- Keep the way I have it composited with separate defocus (depth of field blur) nodes on each tree (could add a weaker one to the butterfly as well) and live with the couple of frames where the butterfly goes behind the branches. The motion is very fast so it is literally a couple of frames
- Render with a single defocus at the end of the node-chain and edit together a separate render of the frames in the grass.
I am leaning towards option 1 because I like the amount of DoF on the trees but not the butterfly when the defocus is at the end of the chain. If I add DoF to the butterfly I will probably have to render the grass part (where the butterfly needs to be in sharp focus) separately and edit them together as it looks like the DoF is either ver accurate or very inaccurate. The butterfly is slightly blurry in parts even though the DoF value coming from the camera is parented to the butterfly. I should check to make sure that it is working as it is supposed to…
I have been having a number of issues with this scene. I need the Z values in order to make the Defocus work at the end of the chain. But is I use the use that composits the Z values of all the layers together then I can’t get the alpha channels premultiplied and thus it looks like this:
Alpha and layering issues
The solution was to use both nodes and then choose the image out from the alphaOvers and the z out from the Z Combines. This freed my mind from the notion that things needed to be linear in the world of nodes.
Original but poor set up of DoF
I also had a fringing issue on the render layers:
Where it should be:
This was solved when the Defocus nodes was working properly at the end of the node chain.