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Georeferencing

Amelie Davis, Purdue University

Summary

As a result of this lab you should be able to understand the process of georeferencing and be able to carry it out (part A). You should also be able to make a map of the results and gain a basic understanding of how land use has changed during the time period depicted by the aerial photographs (Parts B and C).

Context

Type and level of course
Entry level GIS course for undergraduates.

Geoscience background assumed in this assignment
None.
Best if understand the basics of land use change.

GIS/remote sensing skills/background assumed in this assignment
Introductory lab needed only. Students should know how to add data layers, zoom in and out and locate bookmarks. Would be best to have already done a lab on projections and creating your own maps.

Software required for this assignment/activity:
ArcGIS 9.3 (ArcMap, ArcCatalog and georeferencing toolbar)

Time required for students to complete the assignment:
2 hours for part A + assessment, 1 more hour for parts B and C (optional). To shorten the lab you could also just have them georectify less aerial photos.

Goals

GIS/remote sensing techniques students learn in this assignment
georeferencing

Other content/concepts goals for this activity
Learning objectives/outcomes:

  • Understand what the rectifying process does
  • Know how to georefence any scanned map or aerial photo
  • Perform a basic historical Land Use change analysis

Higher order thinking skills goals for this activity
In part A, students will need to apply what they have just been walked through step by step to a new set of aerial photos of different extents and spatial resolution. They are also asked to evaluate the process of georeferencing and how to improve their results in the future.
In parts B and C, student will need to summarily analyze how land use has changed over time from the aerial photos they just rectified.

Description of the activity/assignment

To prepare for this lab students should manipulate a few aerial photos (hard copies) and any scanned maps the instructor can find and explain how this can be. In class students should be introduced to aerial photography methods and limitations (Campbell's 2002 Introduction to Remote Sensing book does a wonderful job). The professor should spend time defining orthophotos as well a discussion of the parallax effects, perhaps with a demo of the distortion that may occur when georeferencing a photo with more relief. Here students are given a set of aerial photos and asked to register them to a road map. They are then asked to examine the photos to see the change in land use over time. The instructor can decide to have students georeference more than the two aerial photos described in the lab (the 1938 and 1972 ones). These other aerial photos are included in the data download.

Determining whether students have met the goals

The assessment portion of the lab serves to determine whether the students have understood the lab. Students will have met the goal if all the images are overlaid properly on the base map (here roads) and they have made maps of the results.
More information about assessment tools and techniques.

URLs and References

Link included in lab document.

None.

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Other Materials




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