Project Overview
GCS was contracted by Geomatrix (now AMEC Geomatrix) based in Helena, Montana, to conduct comprehensive mapping of infrastructure across a large land area in Ghana, West Africa. This effort was part of an Environmental Analysis report for a mining operation, which required an inventory of base map features, including roads, hydrology, and structures.
High-Resolution Satellite Imagery
To fulfill this project, GCS procured high-resolution satellite imagery from Digital Globe’s QuickBird satellite sensor. At the time, QuickBird offered the highest resolution commercially available satellite imagery, making it ideal for detailed mapping tasks.
Ground Control Point (GCP) Collection
To achieve optimal spatial accuracy, GCS Research conducted on-site data collection in Ghana, gathering Ground Control Points (GCPs) for the orthorectification of satellite images.
What is Orthorectification?
Orthorectification is the process of correcting satellite images to ensure that spatial features are accurately represented in their true geographic locations. This involves measuring the coordinates of all identifiable spatial features visible in the imagery.
Data Collection Methodology
Using hand-held Trimble GeoExplorer GPS units, GCS team members collected sub-meter precision GCPs throughout the study area. The process involved:
- Identifying Features: Team members selected easily identifiable features on the satellite imagery, such as corners of crosswalks or bridges.
- Physical Location Collection: They then traveled to the physical location to collect precise GPS coordinates using the Trimble devices.
All collected GCPs were submitted to Digital Globe for orthorectification. Once the image mosaic was orthorectified, GCS Research utilized Esri ArcMap software to generate feature classes for roads, hydrology, and structures, delivering these as an Esri geodatabase with associated FGDC-compliant metadata.
About AMEC Geomatrix
AMEC has acquired Geomatrix Consultants for $85 million. Geomatrix, headquartered in Oakland, California, employs over 500 professionals across 18 offices in the U.S. and one in Canada. The firm specializes in environmental, geotechnical, and water resources services for clients in the oil and gas, industrial, mining, and municipal sectors.
As Samir Brikho, AMEC’s chief executive, states, “With services ranging from environmental impact assessments to remediation, our earth and environmental offerings are crucial differentiators in AMEC’s portfolio.” The acquisition of Geomatrix is expected to enhance AMEC’s geographic coverage and its capability to provide high-value consultancy services.
Conclusion
GCS’s GPS Control Point Data Collection project in Ghana exemplifies the integration of cutting-edge satellite technology and precise ground measurement techniques to support effective environmental analysis and infrastructure mapping.
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