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Masking
Planar tracking will be corrupted if objects such as actors, vehicles, or foreground objects pass between the camera and the tracked surface. Similarly, tracking is compromised if environmental effects such as changing light level, reflective highlights, or spotlights affect the image. Small occlusions or changes may be ignored successfully due to the robustness of the planar tracker, but for larger changes, the tracker will be less accurate, or tracking may be lost totally.
There are several ways to mask out occluding objects or highlights from SynthEyes planar trackers:
Auto-Mask — automatically-generate a mask based on comparison to the original reference frame.
In-plane masks — static masks on the planar tracker itself, for example to mask out interior holes.
Roto-masks — Animated garbage masks created from the SynthEyes Roto panel.
Planar tracker layering — one planar tracker can occlude another
Alpha masking — an externally-supplied alpha channel acts as mask
Warning : The “Invert” button on the Roto Masking panel is not supported by Planar Tracking. Inverted layers are treated as if they are not inverted. In all known cases, a spline stack containing inversion can be converted to an equivalent version that does not use inversion (and it’s usually simpler).
Each of these methods allows you to prevent a portion of the image from being considered during tracking. You're able to see that directly in the monitor view of the Planar tracking panel; untracked pixels show as a faint colored checkerboard.
You must ensure that there is enough of the image left to constrain the tracker pattern appropriately. For example, a single corner feature does not contain enough information to control the scale of a 2-D or 3-D planar tracker: there needs to be several features spread throughout the planar area.
Where are the controls? Each masking method is largely configured via the Planar Options control panel, which is available underneath the main Planar control panel on larger monitor displays. On smaller displays, pop it up via the gear icon directly underneath the tracker mini-view.
©2024 Boris FX, Inc. — UNOFFICIAL — Converted from original PDF.