Avoid Constraint Overkill
To recap and quickly give a word of warning, keep your coordinate system
constraints as simple as possible, whether they are on trackers or camera path.
It is a common novice error to assign as many constraints as possible to things
that are remotely near the floor, a wall, the ceiling, etc, in the mistaken
belief that the constraints will rescue some bad tracking, or cure a distorted
lens.
Consequently, the first thing we do with problematic scene files in
SynthEyes technical support is to remove all the customer's constraints,
re-solve, and look at the tracker graphs to locate bad tracks, which we usually
delete. Presto, very often the scene is now fine.
Stick with the recommended 3-point method until you have a decent
understanding of tracking, and a clear idea of why doing something else is
necessary to achieve the size, positioning, and orientation you need.
If you have a shot with no physical camera translation—a nodal tripod
shot—do not waste time trying to do a 3-D solve and coordinate system
alignment. Many of the shots we see with “I can’t get a coordinate system
alignment” are tripod shots erroneously being solved as full 3-D shots. Set the
solver to tripod mode, get a tripod solution, and use the line alignment tool
to set up coordinates.
最終更新:2009年03月05日 01:03