Imagemeasurement, LaserLOG, and Merge software applications for precision measurements from very large-scale aerial digital imagery. Booth, D.^*,1, Cox, Samuel¹, Barryman, Robert^*,2, ¹ 8408 Hildreth Road, Cheyenne, Wyoming, USA² 7722 Essex Place, Boulder, Colorado, USA

ABSTRACT- Very large scale aerial (VLSA) imagery has resolutions as fine as 1 millimeter per pixel and provides new opportunities for all types of feature measurement. Direct-dimension measurements such as those for plant canopy or stream widths are an important aspect of resource monitoring. Accurate measurements of these and other features can be more easily obtained from VLSA imagery using the 3 new software programs described here. VLSA images have small fields of view and are used for intermittent sampling across extensive landscapes. Pixel-coverage is influenced by small changes in airplane altitude above ground level (AGL) and orientation relative to the ground, as well as by changes in topography. These factors affect the object-to-camera distance used for image-resolution calculations. ImageMeasurement offers a user-friendly interface for accounting for small pixel-coverage variation among images by utilizing a database. LaserLOG both records and displays for the pilot, airplane AGL measured from a high frequency laser rangefinder. The program also calculates and displays vertical velocity. Merge sorts through large amounts of data generated by LaserLOG and matches precise airplane altitudes with camera trigger times for input to the ImageMeasurement data base. We discuss application of these tools, including error estimates and strategies for accurately handling object-to-camera distance errors. We recommend these software packages as a means for expanding the utility of aerial data.

KEY WORDS: aerial photography, resource measurement, remote sensing, monitoring