Basic Techniques in Forest Photo Interpretation

This training handbook presents a series of practical problems in the use of aerial photos for persons who learn best by doing. Foresters, engineers, and many other land use scientists are fast recognizing the value of aerial photos in their work. Photogrammetry initially gained status through use in mapping, but it can help greatly in solving the everyday problems of timber estimating, range and watershed reconnaissance, and road or trail location. Recent graduates and many experienced foresters have studied existing textbooks and manuals in the hope of learning how to use aerial photos effectively. These foresters may have varying amounts of working knowledge and experience with photogrammetry, but they have one thing in common-lack of success in learning techniques or skills by merely reading about them. Effective use of aerial photos is a skill that can be acquired only by practice. Two general types of information can be extracted from aerial photos: Objective.- Essentially the various kinds of spatial measurements, such as location, direction, length, size, area, and volume. Subjective.- The personal conclusions and interpretations reached by specialists as they evaluate these measurements and other information of a qualitative nature for their various fields. The successful interpreter first learns to make the simple yet precise measurements, which his knowledge and experience will translate into reliable interpretations that will have value in his work.