Previous Topic
Next Topic
Book Contents

Digitizing Scanned Images of Graphs

tsEdit can be used as a simple digitizing tablet by allowing users to draw data points on a scanned image of a 2-dimensional graph or map. To paste an image on the graph select File>Import Bitmap Image. You will be prompted to select a bitmap image (*.bmp) file that is pasted onto the graph.

Once the image is pasted onto the graph tsEdit inquires as to whether or not you want to rescale the tsEdit axes to match the axes of the imported image. Select "Yes" if you will be using tsEdit to digitize data from the imported file; select "No" if you just want the imported image to be a background image.

Remapping Coordinate Axes

To remap coordinate axes to match those of an imported image click "Yes" when prompted, or use the menu command Options>Remap Axes. This will bring up the following window:

RemapWindow

For each point there are two values: the first is entered by clicking on a known point on the imported image; in the second box you enter the value to which that point will be mapped in tsEdit.

Example: If you click on the origin the first box will contain the x-coordinate of that value in the current coordinate system; you would then enter a value of 0 (for the origin) in the second box.

Clicking the Next button prompts you to click on and enter a different point on the X-axis. Similarly for the Y-axis. When you click OK tsEdit will setup coordinate axes that overlap those in the bitmap image.

Note: If there are large differences between the current coordinate system and the one being mapped to, then you may need to repeat the Options>Remap Axes command to achieve the accuracy you need.