Number and distribution of ground control points (GCPs) in corridor mapping

Corridor mapping includes project areas that are significantly larger in one dimension than another, e.g. railways, roads, rivers, etc. For more information about capturing a corridor: Step 1. Before Starting a Project > 1. Designing the Image Acquisition Plan > a. Selecting the Image Acquisition Plan Type.

We recommended that corridor projects include ground control points (GCPs) to ensure an accurate reconstruction. The minimum number of GCPs required for a corridor project depends on the same factors as many other types of projects, including the relative accuracy of the image geolocation, the amount of image overlap, and the length and width of the corridor.

We recommend that you allocate your GCPs so that they are offset from one another, regardless of the number of GCPs that you include in your project. You can consider including a pair of GCPs at each end of the corridor in addition to the set of offset GCPs that you collected along the length of the corridor.

Figure 1. Recommended distribution of the GCPs in corridor mapping.