To register an image, open a view and add the shape files that are in the vicinity of the image. Make the files active by clicking them in the View Table of Contents and click the Zoom to Active Themes button. Then add the image with View > Add Theme. In the bottom left corner of the dialog, set the Data Source Types to Image Data Source. Choose your image and click OK. Make the image visible by clicking the box beside its name in the ArcView Table of Contents.

Quite possibly, your image will not appear in the view. To make it centered in the current view:

• Make it the active theme by clicking on it in the View Table of Contents.
• Click Register Image > Move Image to View.

The Register Image menu label is changed to Register name.tiff identifying the name of the image your are registering. In addition to the control points, there will be two new buttons and two new tools. There purposes are as follows:

Label	Position	Purpose
R	Button	Causes the image to be registered to the current control points
Q	Button	Quits the registration process and clears the control points
A	Tool	Adds a new control point
Z	Tool	Zooms to closest control point

The labels on the screen must be dragged to appropriate positions for the control points. The precise position of the point is the bottom left corner of the box that is being dragged. The aqua label must be dragged to a position on the image while the corresponding yellow label is dragged to the corresponding position on the map. For more accurate positioning, you may wish to zoom in on each point. Click the Z tool, then click near the control point of interest and the view will zoom into the point.

Points can be deleted in the usual manner or added using the tool labeled A. This transformation needs only three points. However, specifying more than three points is likely to avoid problems caused by slight inaccuracies in the point input process.

In the example, there are no easily identifiable points in the corners, so each control point has been dragged to a position that can be identified in both the image and the map.

You can register the image using the current control points in two manners. Clicking the button labeled R will cause the image to move. Clicking Register Image > Register Image will provide feedback on the effect on each point, as well as move the image.

In either case, when the product is running in trial mode, the following registration screen will appear.

Clicking the purchase button will evoke your browser with www.spatial-online.com to enable you to purchase the product on-line, through the Fax or via Purchase Order. When you purchase the product, you will be required to supply your site code (just below the Purchase button). In return, you will get a product key. Insert that key into the Text Box next to Product Key and click OK to register the product. Once you have done this, this registration box will no longer appear.

To run the product in trial mode, click the Run in Demo Mode button. Below the button, the remaining trial period is shown.

Clicking the Cancel button will stop the process.

If you clicked the button labeled R, the image will move immediately to the best fit to the control points. The control points should now be closer. You can examine each one to see how closely they could be fit.

In case you utilized the Register Image > Register Image process, the dialog below will appear.

The list box contains the labels for each point followed by the image column and row, the map control position, the position that the image control was translated to, and the residual error. The residual error is the distance between the desired position (the map control position) and the translated position (where the image control position is moved to).

In case a point has a very high residual error, and is likely to be in error, that point can be excluded from the transformation process by selecting it and then clicking the Remove Point button. At least two points are required to define the transformation. However, using a larger number of points minimizes the effects of small errors in defining the points.

The buttons on the next line are the following:

• Restore: This button will restore all control points, in case you have previously removed one or more, and recalculate the transformation and the residual errors.
• Remove Point: This button will remove the selected point and recalculate the transformation and the residual errors. In case one point has a very large residual error, you may decide it is incorrect and remove it to avoid an inappropriate influence over the transformation calculations.
• Cancel: This button will cancel the process, returning to ArcView without moving the image.
• Accept: This button will accept the transformation, returning to ArcView and moving the image.
• Help: This button will cause this help to be evoked in your default browser.