Lab 3: Polynomial Rectification (Due by 4pm Feb 9)

Introduction

In this lab you will learn how to georeference a satellite image in Erdas Imagine.  

Instructions

Read pages 325-356 of the Erdas Field Guide paying particular attention to pages 331-339 and 342-345. Open the lab book (TourGuide.pdf) and skim Chapter 6. For this lab, you will use a SPOT panchromatic image (panAtlanta.img) as the reference image to rectify a TM image (tmAtlanta.img). You can find these lab files in I:\Students\Instructors\Geoffrey_Duh\GEOG4581\Lab3. Complete the tutorial exercise in Chapter 6 and produce a map composition with three map frames, the unrectified TM image (tmAtlanta.img), the reference image (panAtlanta.img) and the georeferenced image (tmAtlanta_georef.img). You must clearly mark which map frame is the unrectified image, which is the reference image, and which is the georeferenced image. Put your name on the map and submit the map with your report.

Make sure you uncheck the “Orient Image to Map System” on the Raster Option tab when you open the rotated/flipped/stretched images. Produce a map that display tmAtlanta_georef.img and tmAtlanta_rotate.img side by side. Put your name on the map and submit the map with your report.

Answer the following questions.

1. What is a transformation matrix?
2. How many GCPs are necessary when doing a 1st order transformation and how do you calculate it?
3. What is the map projection of your rectified file?
4. Write one paragraph directed at the lay person explaining what georeferencing is all about and how you do it.