How many ground survey control points do I need?

To achieve 30cm survey accuracy, PhotoSat needs at least 3 ground survey control points for areas up to 100km².

To achieve 20cm survey accuracy, PhotoSat needs approximately 10 ground survey control points per 100km² of survey area.

To achieve 15cm survey accuracy, PhotoSat needs approximately 100 ground survey control points per 100km².

Using existing project survey data as PhotoSat ground reference control saves the time cost of acquiring new survey data. This may include the time and cost of constructing and surveying new ground targets. Advanced projects often have hundreds of thousands of dollars in existing survey data that can be used as PhotoSat ground reference.

Many projects have no reliable GPS and/or Total Station ground survey data. In these situations ground targets can be constructed and surveyed. If this is not feasible, features visible on the satellite photos can be identified and surveyed after the photos have been taken.

If it is not possible to get ground survey data, the relative accuracy of the PhotoSat survey will still be better than 20 cm in elevation over distances of up to 5km with absolute global accuracy of 3m.