Tutorial V - Registering and Georeferencing a Satellite Image

From your PC, navigate to the network workgroup computer, "slush." Click on "gis." Click on Ecuador. Copy all of the files into your workspace using ArcCatalog.

Load ArcMap.

Add the following coverages and grids from your workspace: tungroads, tunghydro, and tung_sh.

Satellite Image Registration and Georeferencing

In the layers column, select only the tung_sh layer. Add the Satellite image (tungaster.bmp) from your workspace. An error will pop up regarding its spatial reference. Select Ok. Load the Georeferencing toolbar in the "View" menu. In the layer dropdown of the Georeferencing toolbar, select tungaster.bmp. Right click on tungaster.bmp in the layer column. Select "Zoom to Layer."

On the right side of the Georeferencing toolbar, select the button for "Add Control Points." Add a control point on the east side of the crater rim of the volcano. Pick a feature that can be easily identified on the image and the DEM. A line vector will now extend from the control point. Go to the layer column and right click on tung_sh and select "Zoom to Layer." Place the control point on the DEM on the east crater rim of the volcano (make sure the feature matches the spot you selected on the image). Place the control point. The satellite image will now snap to the crater rim of the volcano on the DEM. Zoom into the image using the zoom tool. Select another easily identifiable location on the image to place a control point (i.e. a prominent river bend, etc.). Click on the "Add Control Point" button. Place the control point on your second location. In the layer column, zoom to the tung_sh layer. Place the control point on the same feature as was done when placing the first control point. The image will now snap into place. Note that the image is not exactly over the DEM. This may be remedied by placing additional control points. If a control point is placed accidentally, simply click on the "View Link Table" on the far right of the Georeferencing toolbar and delete the last control point. Once you have placed enough control points to properly locate the Satellite image, you must geo-rectify it.

Select the Georeferencing button and click on "Update Georeferencing." Next, select the Georeferencing button and click on "Rectify." Click Ok. The image has now been rectified to the coordinate system of the DEM and will plot over the DEM whenever it is opened in the future.

Close ArcMap

If you experience troubles, repeat the above steps until you are satisfied with the results.