Example: Ground Reconstruction

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Example: Ground Reconstruction

With the solved flyover_auto.sni shot open and the perspective window open, right-click Lock to current camera (keyboard: L), click anywhere to deselect everything, then right-click Set Edit Mesh and Mesh Operations/Convert to Mesh. All the trackers now are vertices in a new edit mesh. (If you had selected a group of trackers, only those trackers would have been converted.) Rewind to the beginning of the shot (shift-A), and right-click Mesh Operations/Triangulate. Right click unlock from camera. Click one of the vertices (not trackers) near the center, then control-middle- drag to rotate around the new mesh.

Note : the triangulation occurs with respect to a particular point of view; a top- down view is preferable to a side-on one which will probably have an interdigitated structure, rather than what you likely want. The automatic viewport-dependent triangulation is a quick and dirty head start; you can use clipping planes or the Assemble  Mesh mouse mode of the perspective window to set up a specific triangulation reasonably rapidly.

Lock the view back to the camera. Click on the tracker mesh to select it. Select the 3-D control panel image and click Catch Shadows. Select Cylinder as the object- creation type on the 3-D panel, and create image a cylinder in the middle of the mesh object (it will be created on the ground plane). You will see the shadow on the tracker mesh. Use the cylinder’s handles to drag it around and the shadow will move across the mesh appropriately. For more fun, right-click Place mode and move the cylinder around on the mesh.

In your 3-D application, you will probably want to subdivide the mesh to a smoother form, unless you already have many trackers. A smoother mesh will prevent shadows from showing sharp bends due to the underlying mesh.

In practice, you will want to exercise much finer control over the building of the mesh: what it is built from, and how. The mesh built from the flyover trackers winds up with a lot of bumpiness due to the trees and sparsity of sampling. SynthEyes provides tools for building models more selectively.

If you are following along, keep SynthEyes open at this point, as we'll continue on from here in the section on Front Projection , right before we start with Texture Extraction.

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