Large Scale GPS Controlled Photography

The Inventory and Monitoring Technology and Development Program funded a cooperative effort of the Remote Sensing Applications Center and the Rocky Mountain Research Station to develop a cost-effective and accurate way to acquire FIA plot-level data by interpreting GPS controlled low-level aerial photography of remote areas. This method could be used in lieu of field crews for wilderness or other hard-to-access areas where data collection is time consuming and costly, but remains vital to meeting National and Regional inventory and monitoring requirements. This approach may also be useful for re-measurement of FIA type plots for change detection over time. Declining budgets have compounded the problem in acquiring this critical data and such a method has great potential to improve efficiency.

Historically, aerial photography is an important source of remote sensing imagery. This is especially true when high-resolution imagery has been required. Today, many resource specialists regularly use digital aerial photographs in the form of orthophotos. One of the unique characteristics of aerial photographs is to provide a stereoscopic view of the ground. Stereoscopic analysis can now be performed inside a computer using digital stereo pairs. With the advent of precise Global Positioning Systems (GPS), pre-specified locations on the ground can be captured with aerial photographs. When the aerial photos are combined with software and hardware capable of creating, and managing, large image files, traditional measurements made from stereo pairs are possible in softcopy. This report assesses the state of softcopy photogrammetric technology and its application to forestry. Specifically, this report studies the ability of photo interpreters to capture detailed information from Forest Inventory and Analysis (FIA) forest plots. Digital scans of aerial photos were processed to view stereoscopically. Measurements were collected from the softcopy stereoscopic view and contrasted with the ground crew measurements. The investigation found that measurements captured by photo interpreters (PI) using digital photographs provide accurate estimates of individual tree and forest stand variables. All of these measurements are within FIA tolerances. The measurements made include, tree height, species and condition class. The work presented in this report shows promise for future use of stereo-viewed digital aerial photos applied towards the measurement of forest plots. A second study is in progress, which is focused on statistical techniques required for large area application of the softcopy techniques.

Status: This project has been completed. The following links will take you the project documentation.
Final Project Report:  Final This a large PDF file! (5 MB)
Remote Sensing Tip:  Tip  (PDF file)
Project Poster:           Poster (PDF file)