3D Photogrammetry Mapping Capabilities

3D digital terrain model allows for:

Measuring. Photogrammetry can be used to take before and after measurements and monitor the differences. Measurements include:

Distances
Discontinuities. Examples of measuring joints and shears in a rock foundation include Pathfinder Dam, Glendo Dam , Morman Island Auxiliary Dam.
Volumes of material (e.g., borrow quantities). At Minidoka, we measured the volume in an area that needed additional excavation to determine the volume of concrete needed to fill the hole.
Concrete deterioration quantification
Thickness contours (for example,shotcrete thickness)

Cracks in concrete. At Stony Gorge Dam, we measured crack lengths and locations to determine the baseline conditions to monitor potential crack expansion.
Deterioration. At Guernsey Dam, we measured concrete deterioration in a long-abandoned intake and tunnel.

Topographic Contour Generation. All photogrammetry models generate a detailed digital terrain model (DTM), which is a 3D surface that can be used to rapidly generate cross sections, areas, volumes, and other measurements. A typical two-photo photogrammetry model will have over 100,000 points for a three-dimensional model. These data can be used in many ways, for example:
- At the John Day River, we provided detailed data of large woody debris in the river for habitat restoration.
- At the Pueblo Dam, we provided 3D coordinate data to determine where to place grout holes.
3D Modeling

Foundation stability (measure discontinuities for removable blocks) Examples of geologic mapping during construction include Pathfinder Dam, Glendo Dam , Morman Island Auxiliary Dam.

Contact Rebecca Heisler, 303-445-3172, for more information on photogrammetry at Reclamation.