Creating Ground Control Points

Ground control points can be created/added in any of the following ways:

§  Create a control point at a known precise position, generally a surveyed point

§  Create a control point by clicking on an identifiable location on the terrain or LiDAR (e.g. road intersection or street corner)

§  Import a .gcp (text format) file with control point information

After creating a ground control point, you mark it in the relevant photos using the Control Point Editor. See "Marking Control Points in Photos" in this chapter for information.   

Creating Ground Control Points at Known Coordinates

To create a ground control point at known coordinates:

1.     On the Home tab, in the Add group, click the arrow under Control Points and select Create Ground Control Point. The Control Point Editor is displayed with the newly-created control point selected in the control point table at the bottom of the Editor.

Note:        You can also create a control point at known coordinates from the Control Point Editor: On the Home tab of the Control Point Editor, in the Control Point group, click Add New.

2.     Set the control point coordinates and properties. See "Editing Control Points" in this chapter for information.

3.     Mark the control point in the relevant photos, and then save the project. See "Marking Control Points in Photos" in this chapter for information.

Creating Ground Control Points from Identifiable Locations on the Terrain

To create a ground control point from a specific location on the terrain (including LiDAR):

1.     On the Home tab, in the Add group, click the arrow under Control Points and select Create Ground Control Point from Terrain.

2.     Click in the 3D Window to define the control point’s location. The Control Point Editor is displayed showing a photo viewing window, a photos panel, a control point table, and a sampled photos panel - that gradually becomes populated with photo thumbnails as you mark the control point in photos.

3.     Mark the control point in the relevant photos. See "Marking Control Points in Photos" in this chapter for information.

4.     Modify the control point properties as required, and then save the project. See "Editing Control Points" in this chapter for information.