GEOG 4/575 Lab 7: Geometric Transformation

Due Nov 19.

You will use ArcMap’s Georeferencing Tools and ArcScan extension to do geometric transformation and vectorization of raster images. These are important GIS data compilation tasks when converting traditional paper maps or remotely sensed images into a GIS database. You can also use these techniques to georeference a GIS data layer whose spatial reference information is missing or inaccurate. As mentioned in the lecture, collecting GCPs is the most challenging step in geometric transformation and requires a lot of experience. Pay extra attention to the step of collecting GCPs when doing this lab.

Finish all tasks in Chang’s Chapter 6. Answer and submit all questions listed at the end of this exercise. Lab exercise data are available in: I:\Students\Instructors\Geoffrey_Duh\GEOG4575\Chang_5e\chap6 (or on the textbook CD). Please copy all these folders to your working directory in c:\Users before you start.

Notes:

1. Before you start Task 3, you need to delete the spot-pan.bil.xml and spot-pan.aux that come with the spot-pan.bil file. These files are in the same folder as the spot-pan.bil. If you don’t see spot-pan.bil.xml and see two spot-pan.bil files, then you will need to change the folder option in the windows explorer to see the file extension names. Open My computer and click tools -> Folder Options. Click the View tab and uncheck the “Hide extensions for known file types.” Click OK and you should be able to see spot-pan.bil.xml file.
2. In Task 3, Step 1, continue with the lab instructions even if you don’t see any links in the Link Table. If you have difficulty finding the matching GCPs, click here to see how the roads line up with the SPOT image. You can use the rotate, scale, shift tools on the Georeferencing toolbar to move the image closer to the roads in ArcMap.

Questions:

1) Report the RMSE values (including those of individual GCPs) you got in Tasks 1 and 3. Please insert the screenshots of the Link Tables from both Tasks in your report. Also attach a screenshot of the rectified SPOT image superimposed by the roads.

2) Use the properties dialog window to check the projection information of rect_hoytmtn.tif. What is the projection of the rect_hoytmtn.tif image that you just georeferenced?

3) The hoytmtn.tif image contains scanned soil lines. The hoytmtn_trace.shp contains polyline features. If what you need is a soil polygon featureclass, what additional steps in ArcGIS are required to generate the polygon featureclass? Briefly describe the steps and tools you will use. Use ArcGIS online help to find the appropriate tools.

4) You need a polyline featureclass of the old drainage channels on the east side of Portland for your research project. All you found is a paper map of these drainage channels. Assuming that you only have a large format scanner and don’t have a table digitizer. Please describe the steps to create a drainage channels GIS layer from the paper map.