Adventures in Projection-Mapping, continued
For a recent project, I used this same technique to create a series of tracking shots from still photographs:
As explored earlier in a proof-of-concept video here: From Pencil to 3d, projection mapping (or photogrammetry, if you want to be all scientific about it), is the process of projecting flat images onto 3d geometry in order to create quick-and-easy 3d scene. In film, it is most often used to add depth to matte paintings and backgrounds.
The photographs were projected in front of a virtual camera:
And the scene was recreated in 3d by tracing the features in the photograph with a sculpting tool:
One of the scenes involved falling rose pedals, which were projected onto 2d cards in 3d space.
My favorite was a very high-resolution photograph of a surgeon that allowed me to get the camera in very close.
One persistent problem in using this technique is that the phenomenon of parallax; moving the camera even a tiny bit reveals parts of the scene for which no information in the original image exists. To use the Surgeon for an example, moving the camera to the left or right would reveal areas of the background which were obstructed by the surgeon’s head. This results in stretching, repetition, and other artifacts which destroy the illusion of reality.
To solve this problem for this project, I broke the scene up into layers, based on their distance from the camera, and proceeded to paint-out or otherwise fill in detail where it was necessary.
First, a layer had to be created for the glasses, which in this shot were the source of the greatest parallax issues:
Parts of the surgeon’s face which had been obstructed by the glasses had to be reconstructed:
And the Background had to be filled in a bit:
And the result of all these layers:
The process of camera projection can be taken one step further, and applied to actual moving video. The technique, called Rotomation, involves motion-tracking a shot and recreating all movement in the scene with lo-res 3d geometry (read: ANNOYINGLY DIFFICULT!). This is a major technique used in the coversion of 2d films to 3d.
Actually, I’m working on a rotomation project right now! So hopefully, I’ll be able to post some sexy 3d action of this sort soon! Stay tuned!