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Modeling
GeoH tracking relies on having an accurate model of the object being tracked.
When the model does not match, tracking will drift off course, and eventually crash and burn. As a result, some real attention must be paid to creating or obtaining a suitable model. For example, if a car is to be tracked, it must be a model of that car, not just any car.
Cool! The number and placement of vertices in the mesh does not matter; tracking performance is largely independent of mesh size, by careful design.
You can import models via File/Import Mesh, typically an OBJ file or DXF. GeoH tracking models might be just a few hundred triangles, tens or hundreds of thousands. Tracking performance is only gently related to the model size, by careful design.
Tip: You can use the Mesh De-Duplication features of SynthEyes to reduce file size when you have many versions of a SNI file using the same mesh. See the SynthEyes User Manual for details.
That said, you may want to eliminate irrelevant portions of models before tracking, so that they aren't in the way. For example, for a shot tracking a chest and arm, there's no point having a full-body model.
You can use the perspective view's Lightsaber Deletion tool (on the Mesh toolbar, or the Mesh operations submenu of the right-click menu) to rapidly remove large portions of the mesh.
In simple cases, you may be able to construct an appropriate model using SynthEyes's built-in geometric primitives, especially box, cylinder, cone, plane, or sphere. (If the only thing you are tracking is a plane, use Planar Tracking; if it must be deformed then use GeoH tracking!)
Ideally, you'll have exact measurements of the size of the primitive object being tracked. (Stop laughing!) More frequently, you won't.
To find dimensions of primitives, you may be able to use the Pinning tool, which is introduced in the later section on Initial Alignment. Basically, it allows you to match
your mesh to the imagery, scaling the coordinate axes individually until a match is obtained. Refer to the "Determining Individual Axis Scaling" section for details.
When a primitive is close to what you need, you can edit it, either in SynthEyes or in your 3D animation application, to get what you want. Again, lightsaber deletion is handy.
Be careful to consider the end caps of a cylinder. The SynthEyes cylinder primitive has end caps, and left alone they will be part of the tracking. If the cylinder doesn't end in the real world exactly with an end cap at that location, tracking will go poorly or fail. So if there's no proper end to a cylinder in the real world, be sure to either delete the end cap (select those faces, then delete selected faces), or use the do not track layer to prevent the endcap from being tracked.
Important! If you are tracking an object that has an axis of rotational symmetry (which you will lock), such as a sword, you must build the object so that the symmetric axis is the Roll axis, ie Y for Z-up or Z for Y-up, so that you can lock the roll without interference from the other axes, due to rotational axis ordering.
You can model more complex objects in your own animation package, from measurements or photos, or use a photomodeling application. Note that SynthEyes has photomodeling (mesh building) capabilities as well, see "Creating Meshes from Tracker Positions" in the manual. Those SynthEyes capabilities are most useful for models with relatively small numbers of well-defined (corner) vertices, ie man-made technologic objects, rather than a high density of surface features more typical for other photomodeling applications; they may be complementary in that regard.
Whether the model is created in SynthEyes or elsewhere (then imported to SynthEyes), be sure to include a high enough density of vertices to accommodate sufficiently smooth deformation, if the mesh will be deformed. Similarly, it may need to have sufficient detail to accurately indicate areas not to be tracked. See the later section on Do Not Track and Deformation Layers.
If the mesh is a SynthEyes primitive, you can change the vertex count from the 3- D panel by selecting it, then selecting the # tool, which lets you change the grid count for each axis. You should do that first, before setting up any vertex maps, because change the grid count will remove any existing vertex painting.
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