Never even think something is already done …

After fiddling with the skin shader and lashes for Ara, I thought it a good time to start to experiment with some lighting and compositing work. The main idea being to have an environment to test the different shaders for Ara and to spot some possible problems.

I chose the very first shot as test bed for my experiments.

I use all linked assets into my scene files and the last addition to Ara were her lashes – as separate objects – so I linked those as well and … first surprise ! The lashes imported but never linked correctly to my armature proxy. After some fiddling I decided to completely reimport Ara and associated objects. I have the feeling that I might might be doing this more often in th future, so I made a quick howto for me to not forget all the small little details to get it right.

Next came the baking of the cloth simulation. I had already invested quite some time into this topic, so it should just be a setup-click-and-wait kind of thing.

Ha, so wrong !

I the past I had concentrated on the skirt part of Ara’s dress and quite neglected the upper part. Now I had a wider view and recognized that the current setup just isn’t working. This insight resulted in a separate collider object for the dress, a reworked weight-painting and remodelling of the dress mash and dress colllider as well as a slightly different setup for the cloth simulation itself.

Its better now, but I see now that I will have to refine this from shot to shot.

Ok, next came the lighting setup – no real surprises here (for the moment) – and accompanying the compositing part.

The topics I wanted to cover were

  • separate layers for each light group (main, ambient, moon, cage lights ..) for each part (background, Ara, cage) to have maximum freedom for balancing the lighting
  • vector blur for all objects
  • DoF
  • Play around with some nice glow effects
  • Find a way to light a night scene with a path in the shadows of moonlight were the main light source is coming from a cage.

Well, the first point in the list was easy. The funny things started when I tried to use the vector blur. I have Ara and the cage on different render layers and combine them using the Z-Combine node. Well when using the vector blur ( or any other blur node) this will not work correctly anymore, as the z information is sharp and not blurred at all ( and this isn’t possible anyway). I have not yet a solution, but I have to somehow create a mask originally derived from the z-buffer of both layers and apply the same filter operations on this mask as well. At least thats my theory for now.

Pure alpha-over will not work, as I have intersections ( Ara holding the cage).

Another thing which is bothering me is that I do not seem to get a vector blur on my background, which is realized as set ( set in the render panel, where you do not have any selection possibilities). I have to investigate this further.

Another immensely annoying thing suddenly popped up again: all seams on Ara’s dress  were clearly visible again. I thought that baking the normal map from bump maps in blender 2.5x was the solution for this ( see this post for more info ). As it turned out, this is not he solution, as blender 2.5x has the same behaviour.

After long ( very long) experimentation I finally found the culprit which causes this:

It seems (no pun intended) that around seams blender is using areas of the texture map beyond the actual uv-mapping, maybe for blending/smoothing purposes. The default setting in texture paint mode for the projection painting is to have a bleed value of 2, which means that blender will paint also 2 extra pixels outside the uv-mapping. This value is ok for color maps but obviously too small when drawing bump maps. An increase to 4 or higher solves the problem – in principle.

What it means for me is that I have to repaint all seams in the bump maps on my relevant models with a higher bleed value.

The DoF point was another source of new work. In the early animation phase I created a camera rig with all nice controls for positioning, targeting and controlling the lens value. What I didn’t think of at that time was to include a control for the focus point as well … Ok, time for a new reimport session for the camera rig.

And finally I quite clearly see that a lot of polishing will have to go to the animation done so far. But that was to be expected.

All in all a very informative and in the end productive weekend. To show you the outcome of all these explorations I have uploaded a 4 sec shot of the shot. It’s a very early glimpse of what is to be expected and still no vfx ( glowing lights) done here. The irony here is that in this clip Ara’s  hands are rendered black due to rendering time constraints.

Author: loramel


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