This post will cover my multipass workflow, my experiments with smoke, and a whale character from the script including some simulations and the swim cycle.  This will likely be the last Isaac and Isabelle post for a while, as I’m gearing up for thesis year and expect that it will take over my personal work schedule for the next six or seven months.  I’m really excited to work on my thesis project, I’m going to do some live action with a heavy lean on compositing and grading. So lots of post work and still lots to show on the blog, but a very different kind of work.  Something I don’t really show on finlay.to very much, so that’ll be fun.

Anyway, here’s the state of affairs as Isaac and Isabelle goes into hibernation.  I’ve been animating all summer, but not as much as I’d planned to, summer courses and life in general just got in the way.  But I have finished blocking out most of the shots, started the special effects, rigged the whale with a nifty swim cycle, set up my render workflow and locked the first handful of shots.  So far working on Isaac & Isabelle has been a blast, I’ve learned quite a lot that’s been seeping back into the freelance work I do.  It’s the kind of thing that on the one hand I cant wait to be finished and to start showing It off, but on the other hand I’d love to just keep solving these little CG puzzles forever.  So for this post I’m going to go over some of the final decisions I’ve made over workflow.

Click a link to jump to its section:  MULTIPASS MAKO THE WHALE SMOKE

Multipass Workflow

So I decided to go with multipass 32bit OpenEXR renders out of cinema into a compositing package (probably Nuke), then out to Final Cut as QuickTime ProRes4444 video.  I’ve really started using ProRes for all my edit files, even if just as proxies- I can playback 2k footage in real time on my laptop, which is amazing.  I’ve made lots of little additions to this workflow to accommodate software and post effects. For example so that I can apply a barrel distortion effect without scaling the center pixels I render all my frames 10% larger than I need so I can shrink the perimeter of the frame instead.

I’ve also started working almost exclusively with 32-bit OpenEXR files. Working in 32 bit is definitely the way to go if you can, the colour correction capabilities are endless and have saved me having to re-redner in more than one occasion. In Isaac & Isabelle the large dynamic range lets me grade to my heart’s content, and since I’m adding the light in multiple passes I can adjust the light levels separate to each pass.  I prefer compositing the lights separately even though it’s a little more complicated, it lets me have aesthetic control for all the layers as they come together, so I can tweak every single one from anywhere on the pipeline, and with the object buffer masks I can set different levels for each element in the scene.  For example Nikolai ended up a little dark in the render so I brightened up the key pass and ambient pass separately and then lessened the ambient occlusion pass.  If this were a moving scene you’d have to roto out all the elements over time to make a change like that, but the object buffers let me pick out the layers I want to change.

I’m going to try to quickly explain what all these passes are for: I used the an infinite light for the sun, it’s the only conventional light source, this gives the shadows and sun-lit areas.  Then I did an ambient light pass which is a light coming from all directions that has no shadows, this is used in the areas that shadows are cast on in the key pass.  I put ambient occlusion onto the ambient light pass to give it a sense of dimension using the AO effect of shadows that come from no single direction.  Then I masked the shadows out of the key pass and put a graded version of the ambient light pass in their place.  This means that anywhere the key pass casts shadows the ambient pass is used, to create the shadow mask I had to write a little shader that either emits white luminescence or is totally black (when in shadow).  Then I used the object buffers to tweak the single elements that I masked off in the render, like adding the sky for example.

The ambient light is in place of the scattering of Global Illumination, where the light from the scene would bounce around and light geometry from reflected angles.  I don’t have fast enough computers to do everything with calculated GI so I had to fake it.  I did some comparisons of GI renders against this multipass method and the difference was negligible.  The GI bounced light that filled the shadows was definitely more accurate, but without knowing what to look for it doesn’t nescessarily look better, just different.  Since I’m not exactly going for photo-realism it works quite well, the result ends up being a lot cleaner and more stylized.

Here are my separate passes (in order; Key Light Pass, Ambient Light Pass, Ambient Occlusion Pass, Shadow Mask Pass, Object Buffers, Depth Pass):

Here is a bare-bones version of what the nuke pipeline might look like.  The comp I used to create the first picture of this post was obviously much more complicated but this gives an idea of how the elements come together to create the final image:

Mako the Whale

Mako was a fun character to design, I didn’t really use any drawings because I had the image in my head.  There’s a scene in the film where Isaac is daydreaming out the window and a big whale floats by, since there are only a few shots of Mako I didn’t go crazy with the rig.  The whole character was finished in an afternoon, which was a nice change of pace.  I rigged the whale with a single spine using the spline IK system and then controlled the rig with null handles.  I love spline IK’s because they give you really fluid controls, at first I was just using regular IK with four bones and the deformation was very boxy, even with properly enveloped weights, so I made a new spine with seven segments. With spline IK the bones follow the spline, so I could control the rig with five handles that could move across any of the bones, as they are only changing the shape of the spline.

Here is software render for a test of one of the shots of Mako.  There are still lots of changes to be made but I needed to have these scenes at least partly animated so I could figure out the camera angles and subsequent shots:

Smoke POOF!

In the film, whenever imaginary characters are addressed by anyone other than Isaac they disappear.  This happens twice on screen, and in the script we wrote in that they disappear into a puff of smoke (or smoke and feathers in Nikolai’s case).  Here is some smoke I cooked up using separate red green and blue lights so I could grade each light separately in post.  I used PyroCluster in C4D, which is by no means a great smoke engine but since there’s already a cartoony style to the short I think I can get away with it.  So here’s my original render:

And here is a composit test, I think the timing needs to be tweaked a bit but so far so good:

Okay so that’s it for now, it’s been a long long go and I could use a break from the project.  I’m confident that coming back with fresh eyes next summer will breathe new life into the project for the final leg of the journey.  I’m also really stoked to be working with live action, and I can’t wait to get going with some of the comps I have cooked up.  So yeah, new sections of the site, new projects, new school year, all things are new and fresh again!