Using the shake Multiplane node on Free Jimmy –
November 1st, 2006,08:02 AM
At Storm Studio we finished our first CG feature in April. The main compositing job was done in abut a year involving artists from a number of countries who all came and worked at Storm Studio in Oslo. Much of the compositing job involved comping in matte paintings and color correcting elements. The renderman rendered footage was generally generated as one layer, so working on separate elements required what we called id-passes. These were renderers where every item in the frame had an identifying color. So to color correct a given character, we would key the id-pass for the id color of that character to get a mask for it.
On Free Jimmy we used the new Multiplane node in shake quite much. Even though the node tended to be a bit difficult to work with at times and a bit buggy, it was used extensively throughout. One application of the node was to layer matte paintings in shots with moving cameras in order to generate paralax between layers of paintings. Much of the movie takes place on the moors with mountains as distant matte paintings. The 3D sets were quite small and relied heavily on matte extensions. One problem with this was to keep the placement of paintings consistent from shot to shot. One thing we did to keep track of this was to make a Multiplane node for specific sets. The node would be set up so that if we imagined the set being in the center of the Multiplane node, matte paintings were positioned in a circle around the center facing the set. Note that layers in the node may be rotated, so they need not be aligned in straight layers. Camera data was exported from Maya and imported into the Multiplane node for each shot. So sstarting a new shot would involve loading the pre-made Multiplane node for the set in question, loading in the camera data and hooking up the footage. In this way the backgrounds would be the same each time the camera pointed in a specific direction.
Another use of the Multiplane node was to create rooms behind windows. We would get rendered footage from a city set where the windows would be empty. Rendered masks for the windows made it possible to make them transparent, revealing whatever was behind them. The problem was that there was nothing. Enter the Multiplane node. Rooms were constructed bye making layers to act as walls. These could be anything from drawn artwork to plain Color nodes. These were set up as layers in a Multiplane node. To guide in the placement of these, Locators were set up in Maya typically at the corners of windows and where we wanted the corners of the room to be. These were then imported into the Multiplane node and would outline the geometry we were trying to build. It was then a matter of scaling, rotating and aligning the wall layers to build rooms where the Locators were. Your can attach layers to locator points in order to simplify placement. The Maya camera was also imported into the node. The output of the Multiplane node would then be comped in behind the footage with the transparent windows.
I also used the same method to comp in moving posters in the intro sequence (see attached images). The surface where the posters were going to be were green so that I could key it. Locators were again placed in Maya at the corners of the poster space. The posters were animated to move up or down before entering the Multiplane node. The attached images show the original footage, the node tree and the inside of the Multiplane node. The quicktime shows the finished shot.
Visual Effects Supervisor