lq1() CHAPTER 13

·ng and Geographic Systems

Electromagnetic Energy and Spectral Response Patterns Spectral Reflectance of Vegetation,

Soil, and Water Atmospheric Effects

Aerial Photography Aerial Cameras and Photographic Coverage Film-Filter Combinations Scale of Aerial Photographs

Photogrammetry

Photographic Interpretation Fundamentals of the Interpretation Process Tree Species Identification Photo Mensuration

Broadly defined, remote sensing refers to any meth­odology employed to study the characteristics of objects from a distance. Human sight, smell, and hearing are examples of rudimentary forms of re-mote sensing. The rype of sensing systems we treat in this chapter operate on the principle of recording electromagnetic energy over a broad range of the electromagnetic spectrum, from ultraviolet to radio wavelengths. These systems take on various forms and can be operated from aircrafi or from space.

Historically, the most important form of remote sensing used in forestry has been aerial photogra­phy. For example, aerial photographs have been used for decades to aid in the forest-sampling and forest mensuration processes. Aerial photographs provide an efficient means of obtaining a detailed

• "bird's-eye" view of forest conditions on even the most extensive, remote, and treacherous of terrains.

THOMAS M. LILLESAND

Forest Damage Assessment Additional Applications

Nonphotographic Remote Sensing Systems Solid-State Array and Video Cameras Thermal and Multispectral Scanners Side-Looking Radar

Earth Resource Satellites Landsat SPOT Othe Space Systems

Geographic Information Systems

References

A' valuable as aerial-photographic techniques have become in forest management, these proce­dures are limited to the study of images recorded on photographic emulsions. These materials are sensi­tive only to energy that is either in, or near, the visible portion of the electromagnetic energy spec­trum. Sensors such as thermal scanners, multispec­tral scanners, and side-looking radar employ wave­lengths expanded beyond the photographic range; in addition, these nonphotographic sensors rypically record image data in a digital format so they can be analyzed by computer-processing techniques (I, 4, 5).

Today's forest manager has ready access to a broad array of remote-sensing data prod­ucts-ranging from 35-mm photography to high­resolution digital satellite data collected on a global basis. The objective of this chapter is to describe

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