Engauge Digitizer - Automatic Point Graph Tutorial

Engauge Digitizer - Automatic Point Graph Tutorial

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.

Automatically Digitizing A Point Graph Image

The following steps automatically digitize a linear cartesian graph with one curve.

Import the pointplot.bmp case from the Samples directory, using File/Import as shown. Not shown are the other methods of importing: using the "-import" command line option, by copying and pasting, and by 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

View the processed image by selecting the View/Processed Image menu option.

Tune the discretize settings using the Settings/Discretize menu option, so unwanted information in the image is removed. The dialog that appears is explained at Discretize Dialog. For the PointPlot sample image shown here, the discretize settings are Intensity, from 90 to 99.

Remove the grid lines from the original image using the Settings/Grid Removal menu option, so unwanted information in the image is removed. The dialog that appears is explained at Grid Removal Dialog. Note that this step is unnecessary for the PointPlot sample image shown here.

Click on the Point Match button.

Click on the point in the processed image that is the best example of the type of point you want. A blue box will appear around the candidate point that best matches the sample point you picked. In the example below, the leftmost point was chosen as the sample.

Mark the candidate image point as either Accepted or Rejected by pressing the Right Arrow or Space Bar, respectively. If you accept the candidate point then it will turn green, otherwise it will turn red. A new candidate point will then be displayed. To unmark the previously marked point, press the Left Arrow.

Leave Point Match mode to assign all accepted points to the current curve, by clicking on the Select button, or any Digitize toolbar button other than Point Match. If no points are acceptable, reject and/or unmark all points before leaving Point Match mode.

Export the curve points into a tabular text file using the File/Export As menu option as shown. Not shown are the other methods of exporting the curve points from the curve geometry window: copying and pasting, and dragging and dropping