Setting the AT (Aerotriangulation) Area

Setting the AT area defines the area of the project on which PhotoMesh should perform aerotriangulation. Aerotriangulation is the process for determining the correct position and orientation of each of the project photos, based on inputted photo information, ground control points and tie points. If a project’s photos do not have fully trusted camera positioning and orientation information, this process must be performed before generation of the 3D mesh model. PhotoMesh uses the highest-performance photogrammetry, computer vision, and computational geometry algorithms in performing aerotriangulation.

The defined AT area can include all the project’s photos or be restricted to only the photos within a specific area on the terrain. This enables you to perform aerotriangulation on a small subset of the project to validate camera parameters and build settings and check the resulting AT and reconstruction tiles before building the full project. The area for the aerotriangulation can be defined by either drawing or importing an AT polygon.

If project photos have no positioning information, you should manually set an initial AT area based on an estimation of the geographical area of the project, which will then be adjusted by PhotoMesh in the aerotriangulation step.

There are two indicators in the 3D Window that photos are outside the current aerotriangulation area:

§  When photos are "colored by status" (See "Selecting Camera Symbol Size and Color" in this chapter), the camera symbols for these photos will be colored in grey.

§  When "Do not show excluded" is selected (See "Displaying Camera Symbols" in this chapter), the camera symbols for these photos are not displayed.

Note:    Photos that are outside the currently defined AT area are still considered part of the project and therefore the Exclude check box remains cleared in the photo list.