The residual report contains the residual errors of the points in your project. Residual errors are the difference between the coordinates that you entered for the ground control points (GCPs) or tie points and where the points are according to the computed math model. To understand how to evaluate the points in your project, see Troubleshooting the math model solution.
To edit points in the report
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In the table in the Residual Errors window, click the row with the point you want to edit, and then click Edit Point.
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In the viewer, click the new location of the point, and then on the toolbar, click Use Point.
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In the GCP Collection orTie Point Collection window, as applicable, under Working Image, click Accept.
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In the Accepted Points table, verify the results.
If the point is unacceptable, select the same point in the table, click Edit Point, and then repeat steps 1 to 4.
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If the point is still unacceptable, in the Residual Errors window, consider doing one of the following:
- To remove the point from the project, click Delete Point.
- To make the point inactive, in the first column of the table, clear the check box.
- If the point is a GCP, and you want to change it an independent check point, click Change to Check Point, as applicable.
When you change the point to an independent check point or make it inactive, the point is removed from the math-model calculation, but retained in the project. OrthoEngine calculates the difference between the position of the points and the position determined by the model, and includes the error in the residual report. Therefore, the points provide an independent accuracy assessment of the math model.
Note: Any changes made to GCPs or TPs renders the current math model out of date. When a math model is out of date, all information related to that model, such as residual errors, is also out of date. OrthoEngine indicates that a model is out of date by displaying the outdated information in red text and showing a red status message that reads, "Model needs recomputing". To maintain an updated model, in the Residual Errors window, click Compute Model. After the model has been updated, the information is again displayed in black text.
Tip: When selecting items in the table, you can select a group or a range of items. To select a group, click the first item, and then while holding down hold the Ctrl key, click one or more additional items. To select a range, click the first item in the range, and then while holding down the Shift key, click the last item in the range.