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1. Geometric rectification Homework 6 CE403, 2008

2. Description • Objective: geometrically rectify a portion (~2km*2km) of SPOT image over West Lafayette area • Reference (GCP): to be measured from the USGS digital ortho quad (DOQ). DOQ is used as the reference image • Methodology: see the example • Requirements: • at least 6 GCP and 6 check points need to be measured • 10 meter spatial resolution for the rectified image • Data: ftp://ftp.ecn.purdue.edu/jshan/ce403/project6/ • Hand in: a report including (max. 4 pages, 12 font, 1.5 line spacing) • A brief description of the work • The rectified image with coordinate grid (you may use ArcView or ArcGIS for output) and scale info in Letter format • Layout of your selected GCP and their residuals • Layout of your check points and their differences • Evaluation/discussion on your results • Due: April 1 (Tuesday), 2008 CE403, 2008

3. Where to get help ? - Pdf documents • FieldGuide: photogrammetry principles • TourGuide: step-by-step tutorial by modules • OrthBASE: orientation, matching, triangulation, DEM generation • StereoAnalyst: feature collection, stereo map compilation CE403, 2008

4. Where to get help ? on-line manual CE403, 2008

5. For the “geometric rectification” project, check FieldGuide: Chapter 9 TourGuide: Chapter 6 One-line manual : CE403, 2008

6. A worked example – tutorial Landsat image is to be rectified based on SPOT image, Atlanta CE403, 2008

7. Image to be rectified – Landsat TM To display only one band, use Raster > Band Combinations dialogue box as below Choose one desired band to display D:\IMAGINE 8.6\examples\tmAtlanta.img CE403, 2008

8. Reference image – SPOT Pan • Load the SPOT Pan image in a separate viewer. • This image will be used as a reference image, i.e., any location on this image can be used as (2-D) ground control. D:\IMAGINE 8.6\examples\ panAtlanta.img CE403, 2008

9. Steps for geometric rectification • In the first view (the image to be rectified), run Raster > Geometric Correction command • Choose Polynomial in the Select Geometric Model dialogue box, then click OK. • Click Close for now as below. (will make selection later) CE403, 2008

10. Steps for geometric rectification Choose OK in the right window (Existing Viewer is checked) At the following prompt, Click the second viewer (the one to be used as reference). This step let you choose the reference image. CE403, 2008

11. Steps for geometric rectification • Measure GCP. Note measure the 1st image (image to be rectified) first, and then the 2nd image (the reference image) • 1st and 2nd polynomials can be tested. Rarely go beyond 2nd order. However, you can test what happens if so is chosen. • Measure a number of check points to evaluate the quality of rectification • Analyze the error distribution and decide if more GCPs are needed and where. • Check the on-line TourGuide for details. CE403, 2008