Skip To Content

Add GCPs to your ortho mapping workspace

Available with Advanced license.

The steps below describe how to import or manually add ground control points (GCPs) to your existing workspace. GCPs can be added, edited, and managed in the GCP Manager and subsequently used in your ortho mapping project.

  1. Click the Import GCPs tool, which is used to import GCPs stored in a .csv file or a text file.

    Manage GCPs button drop-down menu

    The values should include GCP name, X coordinate, Y coordinate, Z coordinate, Horizontal accuracy, and Vertical accuracy. The spatial reference of the coordinates should be provided while importing the GCPs. Sometimes GCP data comes with photos of the location where the GCPs were measured. If there are multiple photos for each GCP, the GCP label should include a number, which will be used as a unique identifier. For example, GCP20_ov.jpg, GCP20_1.jpg, and GCP20_2.jpg are the photos for GCP 20.

  2. After the GCPs are imported, click the Manage GCPs tool to open the GCP Manager pane, which allows you to add the corresponding tie points for these GCPs.
  3. Click the GCP point in the list, and corresponding images that overlap with the GCP appear in the image list.
  4. Click the Add GCP or Tie Point button Add GCP or Tie Point to add an image tie point in the viewer.

    The image points for other images will automatically be added by the image matching algorithm when possible. The Clear Links button Clear Links is used to delete tie points from images, and the Delete GCP button Delete GCP is used to delete GCPs and the associated tie points from image viewers.

    GCP Manager pane

Notes and tips

  • If you don't have a GCP file and you need to measure GCPs on a reference map, use the Manage GCPs tool to enter a GCP by clicking a location on the map and adding the corresponding tie points in the viewers.
  • Double-click a GCP in the GCP list to pan to the GCP location in the image viewer at the current display scale.
  • When the pointer is in point collecting mode, you can press and hold the C key to switch to the explore pointer.
  • If you want to enhance the image in the display, the shortcut to switch dynamic range adjustment (DRA) on and off is Ctrl+D.
  • The shortcut to zoom to full extent of the image is Ctrl+F.
  • If you have a georeferenced raster layer (raster dataset, mosaic dataset, or image service) that has a resolution similar to your image collection, you can add it as a reference to compute GCPs using the Compute Control Points geoprocessing tool.

To learn about creating ortho mapping products, see Generate ortho mapping products.

Related topics

In this topic
  1. Notes and tips