To use control points in an alignment they must be measured in the images that observe them using the Image Measurements tool on the Alignment tab.
You can import control points, their manual image measurements, and their control point roles from Inpho .prj files if available.
Measure control points
To measure control points, complete the following steps:
- In the Project Tree pane, select the alignment containing the control points you want to measure, and click the Alignment tab.
- On the Alignment tab, click Image Measurements.
The Image Measurements view appears.
- On the Image Measurements view, in the Control Points table, click the row number of a control point you want to measure.
The images containing the chosen point are listed in the Image List. The first image in the list is shown in the Image viewer.
- In the Image viewer, click the exact location of the control point in the image and go to the next image.
Note:
To go to the next image, you can use keyboard shortcuts or click the image in the Images table.
Repeat this step for all the image candidates.
Note:
You must make at least two image measurements for a control point to be used in an alignment.
After two manual measurements, suggestions appear automatically in the remaining images in the Image List. Automatic suggestions are image measurement suggestions that are updated in real time based on the image orientations and the previous image measurements.
Tip:
To disable individual image measurements, uncheck them in the Image List.
- Repeat steps 3 and 4 for each control point you want to include in the alignment.
The control points are measured and ready to be used.
You can process the alignment once all the necessary control points have been measured.
Keyboard shortcuts
You can use keyboard and mouse shortcuts to navigate, to browse, and to measure control points.
Navigation in 2D
Use keyboard shortcuts in the image viewers for help with navigating the images.
| Keyboard shortcut | Description |
|---|---|
Middle drag | Pan. |
Middle roll wheel | Zoom in and out. |
Right hold | Continuous zoom. |
Navigation in 3D
Use keyboard shortcuts in the globe viewers for help with navigating 3D scenes.
| Keyboard shortcut | Description |
|---|---|
Click | Identify features in a pop-up window. |
Click drag | Pan. |
Middle drag | Rotate and tilt the view. |
Middle roll wheel | Zoom in and out. |
Right hold | Continuous zoom. |
Image measurements
Use keyboard shortcuts in the Image viewer.
| Keyboard shortcut | Description |
|---|---|
Click | Make an image measurement. |
Shift+click | Remove an image measurement. |
Spacebar | Accept the measurement and go to the next image. Note:A manual image measurement has the highest priority. If there is no manual image measurement, the automatic suggestion is used. |
Browse lists
Use keyboard shortcuts for help with browsing lists in the control points.
| Keyboard shortcut | Description |
|---|---|
F | Go to the next image in the Image List. |
B | Go to the previous image in the Image List. |
Shift+F | Go to the next point in the Control Points list. |
Shift+B | Go to the previous point in the Control Points list. |
Role of a control point
A control point can have two roles: It can be used as a ground control point (GCP) and a check point (CP). Ground control points are used in the alignment processing. Check points are used to assess the quality of the alignment results.
Note:
The role of a control point is specified per alignment. This allows you to use different roles for the same control points in different alignments.
If control points are imported from an Inpho .prj file, the roles of the control point are imported as well. In all other cases, control points are assigned the GCP role by default.
Change the role of a control point
To change the control point role, complete the following steps:
- On the Image Measurement view, in the Control Points table, select the control point to edit.
Tip:
You can select and deselect individual control points by pressing the Ctrl key while clicking. To select and deselect groups of control points, press the Shift key while clicking.
- On the Control Points table toolbar, click Set Role and choose a role from the drop-down menu.
The role of the selected control point is updated and visible in the Control Points table.
You can process the alignment to update the alignment results.
Image measurement status
A control point must have at least two image measurements to be included in the alignment process. The status of a control point is represented by a symbol that indicates the number of images it has been measured in.
The image measurement status symbols indicate the following:
- Red circle—A point has fewer than two image candidates and cannot be used in an alignment.
- Gray ring—A point has two or more image candidates but no image measurement.
- Yellow half-circle—A point has two or more image candidates and one image measurement.
- Green half-circle—A point has two or more image measurements, and there is at least one image candidate that is not measured.
- Green circle—All image candidates have measurements.