The Nature of Geographic Information

1. Overview

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Chapters 6 and 7 consider the origins and characteristics of the framework data themes that make up the United States' proposed National Spatial Data Infrastructure (NSDI). Chapter 6 discussed the geodetic control and orthoimagery themes. This chapter describes the origins, characteristics, and current status of the elevation, transportation, hydrography, governmental units, and cadastral themes.

Objectives

Students who successfully complete Chapter 7 should be able to:

  1. given a regular or irregular array of spot elevations, construct a triangulated irregular network, interpolate contour intervals and draw contour lines;
  2. compare vector and raster representations of terrain elevation;
  3. acquire and view digital elevation data from the National Elevation Dataset;
  4. calculate an interpolated spot elevation based on neighboring elevations;
  5. contrast the characteristics of three global elevation data products;
  6. describe the characteristics and current status of the NSDI hydrography, transportation, and governmental units themes as implemented in USGS' National Map; and
  7. interpret the size and relative location of a land parcel designated in terms of the U.S. Public Land Survey System.

"Try This!" Activities

Take a minute to complete any of the Try This activities that you encounter throughout the chapter. These are fun, thought provoking exercises to help you better understand the ideas presented in the chapter.

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This textbook is used as a resource in Penn State's Online Geospatial Education online degree and certificate programs. If this topic is interesting to you and you want to learn more about online GIS and GEOINT education at Penn State, check out our Geospatial Education Program Office.