Dilate

Constructs a dilated image of the selected object(s). In a dilated image, a particular ratio is used to move every point of the original closer to or farther away from the center point. If the ratio is greater than 1, the image points are farther away from the center than the originals and the image is larger than the original image. If the ratio is less than 1, the image points are nearer the center and the image is smaller.

Sketchpad has both a Dilate Arrow tool and a Dilate command. When you use the tool, you dilate the original object. When you use the command, you create a new object—a dilated image of the original object.

To dilate objects:

1. If you haven’t already done so, select a point to act as the center for dilation and choose Mark Center from the Transform menu. Alternatively, you can double-click the desired center point with the Selection Arrow tool.

A brief animation indicates that the point has been marked as a center for subsequent rotations and dilations.

If you dilate without first marking a center, Sketchpad will mark one for you.

2. Select the object(s) you wish to dilate.

3. Choose Dilate from the Transform menu.

The Dilate dialog box appears, and a dilated image of your selection(s) appears in the sketch.

4. Choose either Fixed Ratio or Marked Ratio, as described below.

5. You can click a point in the sketch to change the marked center, you can click a measurement with no units to set the marked scale factor, or you can click two segments to set the marked segment ratio.

6. When you have chosen the options you want and entered any required values, click on Dilate.

The dilated image appears.

Fixed Ratio

Choose this option to enter a fixed ratio by entering both numerator and denominator.

A ratio smaller than 1 results in an image that’s smaller than the original, and a ratio greater than 1 results in an image that’s larger.

Marked Ratio

Choose this option to dilate your selection based on a marked ratio or scale factor you’ve specified using the Mark Ratio command. This choice is disabled if you haven’t already marked a ratio. However, if you want to use a ratio of two segments that exist in your sketch, you can click the segments now to mark them. Similarly, if you want to use a measured scale factor that exists in your sketch, you can click it now to mark it.