Chapter 10. Working with raster data
This chapter covers
- Georeferencing with ground control points
- Working with attributes, histograms, and color tables
- Using the GDAL virtual format
- Reprojecting rasters
- Using GDAL error handling
In the last chapter you learned the basics of raster processing, such as how to read and write data and work with individual bands, and how rasters use geotransforms to orient themselves to the real world. This was a great first step, but what if you have an old aerial photograph or scanned paper map that you’d like to turn into a geographic dataset? You might want to do that because it’s fun and interesting, or you might want to do a change analysis using this data along with more current imagery. To do that, you must overlay the old data on the new. You can do this using ground control points, which are essentially a collection of points with known locations. This chapter will teach you how to use these points.