The Scale Image option can be used to define the size and location of an image drawing tool in terms of model coordinates. This allows you to use an image as a drawing guide, for example, if you need to graphically trace over an image to define the model boundaries or other geometry.
Scale Image is available:
from the Tools menu or right-click menu, after an image has been added
if you use the Import Image option to add an image, Scale Image is available at Step 2 of the Import Image wizard dialog
A quick way to use Scale Image is with the right-click shortcut:
Right-click on an image drawing tool, and select Scale Image from the popup menu.
You will be prompted to choose a point on the image. Use the mouse to graphically select a point with known coordinates on the image (zoom in if necessary to accurately select the desired point).
You will then see a dialog which allows you to enter the desired X,Y model coordinates of the selected point. Enter the coordinates and select OK.
Repeat steps 2 and 3 to define the coordinates of a second point on the image.
The image will then be scaled to the desired coordinates, and can be used as a drawing guide to graphically create model boundaries or other geometry.
You can customize the image transparency / visibility in the Format Tool dialog, or specify visibility options in the right-click menu.
If you just want to resize or move an image without defining the exact size or coordinates, you can just click and drag an image like any other drawing tool (i.e. you do not have to use the Scale Image option). If you left-click once on an image, the control points on the image will be highlighted, and you can click and drag them to resize the image, or drag the entire image to a new location.