Lab 6

Goal and Background

The goal of this lab was to introduce me to the important image process, geometric correction. There are two major types of geometric correction that are often used, both of which are covered. All methods in this lab were completed using Erdas Imagine.

Methods

First, I performed image to map rectification. I opened a distorted image of the Chicago area and selected a control points tool to start the rectification. I was prompted to select a geometric model, and I selected polynomial. I performed a 1st order polynomial transformation, and this required at least 3 ground control points to be used. To obtain these GCPs, I first selected a point on the distorted image, and found the corresponding point on a map of the Chicago area. When I had the proper number of GCPs, I began to move them to reduce the RMS error. Once I got this down to below 1, I finished the model and saved it as an output file.

Next, I performed an image to image rectification. This process is essentially the same as previously described, except this time I was rectifying the image to one that was previously rectified. This time, I selected the control points tool and polynomial model, but this time I used a 3rd order transformation, which required me to create at least 9 GCPs. I corrected them until I had an RMS error of less than 1.

Results

Sources

None