Establishing Cameroon's National Geodetic Network

In December 2010, MINDCAF selected Fugro to identify, mark and measure a total of 525 points throughout the 475,000 square kilometre territory. The project was divided into four phases:

1. Preliminary study and terrain reconnaissance to identify suitable sites for network points

2. Building the monuments and markers on the ground for each network point

3. On-site GPS observation of each network point and levelling

4. Data processing to calculate the final precise coordinates of the network

Reconnaissance and observations

During the reconnaissance phase which ran from January to March 2011, Fugro worked with MINDCAF representatives from each of the ten administrative regions to select suitable locations. Selected locations included schoolyards, police stations and other public areas where monuments were less likely to be damaged or removed.

When the points had been identified and approved by the government, the next two overlapping phases consisted of building the monuments and performing the precise GPS observations and levelling tie-in. Once the network points were built, 25 reference points and 500 base points were observed.

The survey teams typically observed five to ten points at the same time as the reference points to form a block. This meant that during the measurement of a block points, a total of eight or more survey teams had to be deployed simultaneously to eight different locations spread over several hundred square kilometres and synchronised.

A major challenge for the project was to coordinate the survey teams on the ground during the on-site construction and GPS measurement phases.

A challenging environment

Cameroon’s geography has high mountains in the West of the country, mangrove swamps on the coastal plain, jungle terrain in the east and savannah and desert further inland. We faced numerous obstacles, including flooded rivers and roads and other technical and administrative constraints. Teams were sometimes unable to reach their assigned locations and had to be redirected in real-time by the chief surveyors. Thanks to this and constant communication between the survey teams and the project management team via satellite phones, Fugro was able to complete all ground operations before the start of the rainy season.

Data processing

The reference network of 25 stations was processed with the GAMIT/GLOBK universitary state-of-the-art software. With a unique expertise in using this software, the Fugro team was able to calculate a final geodetic solution in four iterations based on the 58 most relevant permanent stations (maintained by the International GNSS services for Geodynamics 5IGS), the selected stations were in Africa, Europe, and the Middle East. Accuracy of this base network of 25 references stations is then considered to be a few millimetres, as we have Root Mean Square values better than 5 millimetres in planimetry and 9 millimetres in heights.

A reliable foundation

Final project deliverables were submitted to the MINDCAF and IGN France International for final quality control and approval. This phase also included additional training to MINDCAF personnel to ensure the transfer of technology and know-how, so the agency may become self-sufficient in maintaining the network. Over the course of the next few years, MINDCAF intends to densify this base network with several thousand more points.

Supporting a nation's land reform programme

The network created provides an objective, scientific basis for many applications, including measuring and delineating property parcels and building cadastral maps. This in turn has given Cameroon land property information that is critical to the nation’s legal and fiscal system, as property taxes are an important source of revenue for the majority of nations around the world.

Our staff are proud to have participated with MINDCAF on a successful programme that is of such critical importance to Cameroon’s long term economic development.