Levels of Accuracy
PhotoSat provides a range of survey products for variety of clients. The level of accuracy is influenced by the number of ground control points (GCP) and the satellites used to capture images.
If you have existing survey data, we can combine it with our survey data.
Surveying for operating mines and earthworks
For applications in operating mines or earthworks construction, PhotoSat produces elevation surveys with high accuracy: around 15 cm RMSE or better.
To achieve this, we use specific satellites and apply as many GCPs as possible. The accuracy of our elevation surveys typically increases with more ground control points (GCP). See below.
For areas of 100 km2:
| Level of Accuracy | GCPs (per 100 km2) | Over Horizontal Distance | Satellites | Applications |
|---|---|---|---|---|
| <15 cm (absolute) | <150 | 10 km | WorldView-1
WorldView-2 WorldView-3 |
Operating mines:
Earthworks construction:
|
| 15 cm – 20 cm (absolute) | <75 | 10 km | WorldView-1
WorldView-2 WorldView-3 |
Wind turbine construction
Mine development |
Surveying for planning and exploration
For applications such as mining exploration or preliminary planning, high accuracy surveying is not always necessary. When suitable for your application, we can use a broader selection of satellites or apply fewer GCPs.
Even with no GCPs, PhotoSat surveys are still quite accurate at 20 cm relative accuracy. See below.
For areas of 100 km2:
| Level of Accuracy | GCPs (per 100 km2) | Over Horizontal Distance | Satellites | Applications |
|---|---|---|---|---|
| 20 cm – 30 cm (absolute) | <20 | 10 km | WorldView-1
Kompsat-3A Pleiades-1B |
Mine development Mine exploration |
| 30 cm – 50 cm (absolute) | <10 | 10 km | Kompsat-3A | Preliminary exploration |
| 1 m – 2 m (absolute) | <5 | 10 km | ALOS PRISM
SPOT 7 |
Preliminary exploration
Terrain assessment |
| 20 cm (relative) | None | 5 km | WorldView-1
WorldView-2 WorldView-3 |
Preliminary planning
Preliminary exploration |
Surveying without Ground Control Points (GCPs)
In some cases, it may be necessary to complete elevation surveys before ground control points are established. This is often the case in regions where security is not guaranteed, or in extremely remote areas. These elevation surveys are still relatively accurate, at about 20 cm elevation accuracy.
GCPs can be applied later
If ground survey data becomes available after a PhotoSat survey has been delivered, we can reprocess the satellite photos and adjust the PhotoSat survey to match the new ground survey data. The cost to reprocess and reissue the PhotoSat survey depends on the size of the survey area.
For example, survey target areas of 100 km2 can be reprocessed for approximately $2,500 USD.