Description: Steps for digitizing point graphs
Keywords: Engauge Digitizer, browser based documentation, online manual, Digitizing Point Graphs

## Engauge Digitizer - Digitizing Point Graphs

Warning: Not all point graphs work well when automatically matching points in Engauge. Before going any further, you may want to read about point match requirements.

### Typical Set of Steps To Digitize Point Graphs

The following steps digitize a linear cartesian graph with points along one curve:

- Obtain an image file (bitmap, jpeg or other) showing one or more graphs and both axes
- Import the image file using one of the following options:
  - File/Import menu option
  - Copying and pasting
  - Dragging and dropping
- Click on the Axes Point button before entering axes points. These will define the coordinate system
- Click on one of the axes to add the first axes point, then enter its graph coordinates
- Click on one of the axes to add the second axes point, then enter its graph coordinates
- Click on one of the axes to add the third axes point, then enter its graph coordinates
- Click on the Point Match button to automatically digitize many curve points.
- Click on a sample point, and then use the arrow keys to accept or reject points that match the sample point.
- Click on the Curve Points button to manually enter curve points.
- Click on the curve to add a curve point
- Repeat the previous step until the curve is covered with a sufficient number of curve points
- Export curve points using one of the following options:
  - File/Export menu option to save selected curves into a tabular text file
  - Copying and pasting to copy points in the current curve from the curve geometry window to another application
  - Dragging and dropping to copy points in the current curve from the curve geometry window to another application

### Optional Steps

To clean up the image for better performance of Segment Fill and Point Match: steps:

- Show the processed image, rather than the original image, by selecting the View/Background/Show Filtered Image menu option
- Adjust the discretize settings using the Settings/Discretize menu option, until unwanted parts of the image disappear
- Remove grid lines using the Settings/Grid Removal menu option

For a graph that is logarithmic or polar:

- Select the Settings/Coords menu option to bring up the coordinates window
- Select the appropriate coordinate settings

For a graph with more than one curve:

- Select the Settings/Curves menu option to bring up the curves window
- Click on the New button to create a new curve, then enter the name of the new curve
- Repeat the previous step until all desired curve names have been entered
- In the main window, use the Curves combobox to select a curve. While that curve is selected, all new curve points will be assigned to that curve