Softcopy Photogrammetry Dr. Frank L. Scarpace Civil and Environmental Engineering Environmental Remote Sensing Center University of Wisconsin-Madison April 15, 2003 F.L.Scarpace

Outline Definition of Softcopy Photogrammetry Why is this technology used ? Determining Elevations using Softcopy Technology Automatic Terrain Measurement Demonstration of the technology April 15, 2003 F.L.Scarpace

Softcopy Photogrammetry Also known as Digital Photogrammetry Mathematics is the same as in traditional Photogrammetric technology. The images (diapositives) are replaced by scanned aerial images. Measurements and image viewing are on a computer screen instead of through high quality optics. April 15, 2003 F.L.Scarpace

Why Softcopy? The principal reason this technology has been adapted is the potential for almost complete automation of the Aerial Triangulation process. Aerial Triangulation is the least expensive method of determining the orientation of images within a block of aerial photos. April 15, 2003 F.L.Scarpace

Softcopy Photogrammetry Orientation (ASPRS, 1980) 6 Parameters define the orientation for an aerial image at the time of exposure. The location of the image: Xc,Yc, and Zc And the pointing direction: , , and  April 15, 2003 F.L.Scarpace

Measurement of Elevation Once the Orientations for a stereo pair of digital images are known, the elevation for a point in the overlap area can be determined. This is usually accomplished by viewing the images on the computer monitor in 3-D and clicking on the appropriate location. April 15, 2003 F.L.Scarpace

Measurement of Elevation April 15, 2003 F.L.Scarpace

Automatic Terrain Measurement Almost all elevations within Softcopy systems used in production are determined manually by an experienced operator. Potentially this process can be automated, saving both time and money. The ATM technology uses area matching techniques to find corresponding points within a stereo pair. April 15, 2003 F.L.Scarpace

Automatic Terrain Measurement * Many more elevation points can be found using this technique compared to manual methods. * The number of points are comparable to those measured with LIDAR. * Currently, the Automatic Terrain Measurement technology generates too many errors to make it practical. April 15, 2003 F.L.Scarpace

Automatic Terrain Measurement Left Image Right Image Reference Window Search Window Pull-In Region Search Direction Reference Image Search Image SEARCH EXAMPLE April 15, 2003 F.L.Scarpace

Demonstration of ATM April 15, 2003 F.L.Scarpace