Working with Persistent Change Monitoring (PCM)

Persistent Change Monitoring (PCM) is a vector dataset produced by Maxar. This dataset depicts annual changes that were detected based on 30-meter Landsat and 10-meter Sentinel-2 imagery. Maxar hosts this dataset within SecureWatch and makes it available via the platform.

PCM Coverage Map

Dark green: Landsat based change (1998-2020)

Light green: Sentinel-2 based change (2016-2020)

Grey: No PCM coverage at this time

The PCM dataset available in SecureWatch is static and not updated on a regular schedule. Additionally, due to production schedules, some areas may not have the most recent change detection polygons. The most recent PCM changes may be purchased as a separate product. Please contact your Maxar sales representative.

  1. Zoom to level 13 or higher.

    PCM Change Detection layer information is visible at zoom levels 13 through 20. To maintain top performance when using the PCM Change Detection layer within other OGC client applications, the WMS service limits the rendering of polygons to level 13 and higher, and the WFS service limits requests to returning no more than 50,000 polygons regardless of the specified bounding box. See Using Maxar Web Services with Other Third-Party Tools.

  2. On the side panel, select the Layers icon . The Layers pane opens.

    Layers Pane with PCM Change Detection

  3. Select PCM Change Detection. The legend appears.

  4. In the legend, select the Filters icon . The PCM Change Detection Filters dialog opens.

    PCM Change Detection Filters Dialog

  5. In the Show Changes For drop-down list, select a period of years, or choose Custom Range and use the date selectors to set start and end dates.
  6. Select Apply. The map updates to show only the polygons for the time period you set.

    PCM Polygons and Change Detection Legend

More Information

  • Use the slider to adjust a layer's transparency and drag the layers within the pane to change their stacking order. See Changing the Stacking Order & Transparency of Custom Layers.
  • To see additional information about the PCM Change Detection layer, in the Layers pane, select the Action Menu , then select Information.
  • After viewing the polygons on the map and noting the year of a detected change, use the Carousel to find and view imagery from before or after the change. See Comparing Imagery.