In this lesson, we will also continue the discussion of elevation data in more depth, including many additional forms and formats for the representation of terrain as a base map layer. Photogrammetry was historically the primary approach to elevation data creation; in recent years technologies such as lidar and IFSAR have surpassed photogrammetric methods for large area collection. We won't have time to discuss the design and operation of those technologies (they are covered in other courses in the remote sensing curriculum); but, we will discuss the elevation products that are generated from all remote sensing technologies.
We will also continue the discussion of specifications and standards; in this case, focusing on those that drive elevation data development at the federal, state, and county level in the United States. This, and the discussion of orthophoto standards, will set the stage for a discussion of data validation, accuracy assessment, and quality assurance/quality control methods which are a critical part of the overall base mapping mission.
At the end of this lesson you will be able to:
- describe the basic photogrammetric concepts used in creation of digital elevation models;
- explain the characteristics of, and processing methods used to produce, digital elevation models, digital terrain models, digital surface models, and topographic contours;
- discuss the strengths and weaknesses of various types of terrain representation in GIS analysis and applications;
- identify common artifacts and anomalies that occur in elevation data and methods used to correct them;
- identify common elevation data formats and perform conversions from one format to another;
- overlay elevation data with imagery and vector data to prepare for visualization and analysis.
If you have any questions now or at any point during this week, please feel free to post them to the Lesson 4 Questions and Comments Discussion Forum in Canvas.