Control points are positions on the ground that have been accurately measured in a given spatial reference. You can use control points in an alignment workflow as ground control points (GCPs) or check points (CPs). Ground control points are used to accurately georeference the images in an alignment and aid in the optimization of parameters. Control points that are not used as GCPs can be set as CPs, which you can use as a reference to verify the georeferencing accuracy of the alignment results.
Note:
To use control points in an alignment, you must include them in the alignment, and measure the control points in the images that contain them.
You can import control points into ArcGIS Reality Studio from an ASCII text file (.txt) or an Inpho project file (.prj). If the .prj file contains image measurements of the control points, they are included in the import and can be used in an alignment.
Import control points from an ASCII text file
To import control points from an ASCII text file, complete the following steps:
- On the Home tab, click Control Points.
The Select input file dialog box appears.
- Browse to the location of the control points file, select the file, and click OK.
Note:
For every control point to be imported, the file must contain its respective ID, x-coordinate, y-coordinate, and z-coordinate in a single row, separated by a supported delimiter (comma, space, tab, or semicolon).
The Control Points Import dialog box appears.
- Next to Spatial Reference, click Select coordinate system
.Note:
Horizontal and vertical spatial references of the control points should be the same as the camera sessions of the alignment.
The Spatial Reference dialog box appears.
- Choose the appropriate horizontal and vertical coordinate systems for the orientation data by doing the following:
- Click the button below the Current XY header and select a horizontal coordinate system.
- Click the button below the Current Z header and select a vertical coordinate system.
Tip:
- Alternatively, type a search term or EPSG code in the Search box to find a coordinate system.
- Right-click a coordinate system and click Add to Favorites
to add it to your favorites list. - Right-click a coordinate system and click Details
for either coordinate system to see how they are defined.
- Click OK.
- On the Control Points Import dialog box, configure the Parsing settings.
- Click Next.
- For each column, choose the appropriate label from the drop-down options.
- Click Import.
The control points are imported and visible in the Project Tree pane.
Import control points from an Inpho project file
To import control points from an Inpho project file, complete the following steps:
- On the Home tab, click Control Points.
The Select input file dialog box appears.
- Browse to the location of the .prj file, select the file, and click OK.
Note:
If the .prj file contains image measurements of the control points, they are included in the import and can be used in an alignment.
The Spatial Reference dialog box opens.
- Choose the appropriate horizontal and vertical coordinate systems for the orientation data by doing the following:
- Click the button below the Current XY header and select a horizontal coordinate system.
- Click the button below the Current Z header and select a vertical coordinate system.
Tip:
- Alternatively, type a search term or EPSG code in the Search box to quickly find a coordinate system.
- Right-click a coordinate system and click Add to Favorites to add it to your favorites list.
- Right-click a coordinate system and click Details for either coordinate system to see how they are defined.
- Click OK.
The control points are imported and visible in the Project Tree pane.