Question:

How do you create a control point?

Answer:

To create a control point:

1. Set the spatial reference system in the combo-box. 'Cartesian' system can be used to enter non-georeferenced control points for instance in a local spatial reference system. For georeferenced control points, choose the desired spatial reference system before entering coordinates in the table.
   
   
   
   
   
2. Click on Add point to create a new control point in the selected spatial reference system.
   
   
   
   
   
3. Set the control point properties.
   
   
   
   
   1. Name - control point alias
   2. Category
      1. Full: XYZ coordinates will be used (default).
      2. Horizontal: only X and Y coordinates will be used.
      3. Vertical: only Z coordinates will be used.
   3. Check point - Enable this option if you want to use the control point for checking only. In such case the control point will not be considered for the aerotriangulation.
   4. Given 3D position - Edit the control point given 3D position in the corresponding columns. Coordinate units depend on the chosen spatial reference system.
      1. Cartesian: arbitrary unit, same unit for X, Y and Z (for georeferenced control points, Cartesian means ECEF).
      2. WGS 84: latitude and longitude in degrees, ellipsoidal height in meters.
      3. Other: X, Y and height in meters.
   5. Horizontal accuracy - Enter the given accuracy for the X and Y coordinates of the control point. Control points with a higher accuracy will have more weight in the aerotriangulation.
   6. Vertical accuracy - Enter the given accuracy for the Z coordinates of the control point. Control points with a higher accuracy will have more weight in the aerotriangulation.
      
      
      
4. Add image measurements - Select the photo on which you want to add a measurement, find the control point position in the photo, and use Shift+Click to set the image measurement position.