• Client:
  Various
• Appointments:
  2000 and ongoing
• Scope of Work:
  Collection of predetermined ground control points (GCPs)
• Cost of Project:
  Approximately R0.5m per project

MHP have undertaken various survey projects to fix ground control for satellite imagery in South Africa, Kenya, Nigeria, Swaziland, Lesotho, Ethiopia and Moçambique. The spatial accuracy requirement of the GCPs varies according to the usable scale of the satellite imagery but is normally in the range 0.2m to 1.0m for position and 2.0m for height.

Survey conditions in Africa, north of South Africa, are difficult and MHP has developed techniques that work in these countries. The standard procedure adopted by MHP surveyors is:

1. Establish a point of contact in the country of survey.
2. Establish or confirm the survey system in the country of survey. Locate primary control points and verify position and elevation.
3. Obtain all relevant city, country and street mapping prior to commencement of survey.
4. Convert co-ordinates supplied by the client to the local mapping system for navigation purposes.
5. Identify suitable, visible, GCPs from the supplied satellite image chips.
6. Survey the ground control points using Trimble, ProXRS GPS equipment to client's specification. Realtime differential corrections are enabled, thus achieving sub-meter accuracy of the control points. Higer order survey accuracies are achievable depending on client specifications.
7. Prepare control point sketch sheets, photographs and GPS data files for each control point.
8. Confirm the relevant accuracy of the GPS equipment related to the national control network.

KEY RESULTS:

MHP Geomatics has been able to respond to requests to undertake ground survey in Africa within two weeks of instruction.

MHP now has experience in the surveying of GCPs in Kenya, Moçambique, South Africa, Swaziland, Lesotho, Nigeria and Ethiopia.

The work produced by our surveyors is of the highest standard and is in line with international best practice for surveying of GCPs.