CE403, Geometric rectification Homework 6

CE403, 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, 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, Where to get help ? on-line manual

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

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

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

CE403, 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, 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, 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, Steps for geometric rectification Measure GCP. Note measure the 1 st image (image to be rectified) first, and then the 2 nd image (the reference image) 1 st and 2 nd polynomials can be tested. Rarely go beyond 2 nd 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.