Aerial Mapping Spring '13 - Aerial Mapping Spring '13
Getmapping Captures Cape Town Using VisionMap A3 Digital Mapping System
Founded in 1999, Getmapping pioneered the concept of nationwide coverage of aerial photography. Today Getmapping produces its own vertical aerial photography, oblique photography and height data.
Getmapping services a wide variety of business sectors including central and local government, utilities, the emergency services, media and publishing, property and construction, transport, communications and the environment across Great Britain and internationally.
Getmapping, through its African subsidiary Geosense, was commissioned by the City of Cape Town (CoCT) to provide the most detailed imagery of their municipality ever captured. The challenge was to capture, process and deliver over 2500 km2 of high resolution (6.25cm) imagery covering the entire City of Cape Town Metropolitan area.
CoCT is one of the most pro-active Local Authority users of imagery in the world, and employs imagery across many of its service divisions including planning, enforcement and transport. CoCT is growing rapidly and undergoing significant change every year. As a result, CoCT requires regular surveys of its entire region to support a wide range of core services.
The CoCT region covers the City of Cape Town, including outlying suburbs and the Cape Peninsula. The region also includes the world famous Table Mountain Park. As a result, undertaking aerial survey of the area faces a number of challenges created by significant variations in the terrain, as well as having to work around the busy Cape Town International Airport.
Geosense deployed the VisionMap A3 Digital Mapping System to meet CoCT’s challenge. Prior to this project, CoCT has mostly commissioned 12.5cm imagery for their entire region. However, by deploying the A3 system, Geosense was able to provide CoCT with full coverage of their region at high resolution, without stretching their existing budget, and deliver the data in less time than it would have previously taken to produce standard (12.5cm) imagery.
By using the A3, Geosense was able to overcome challenges posed by the area’s terrain and airspace restrictions by flying at approximately twice the height of a conventional survey, with a footprint twice as large. By flying higher, many ATC restrictions were overcome, and by effectively flying half as many survey lines, Geosense was able to complete the project in a fraction of the time it would otherwise have taken. The captured imagery comprised 690,886 frames of imagery captured across 13,025 sweeps.
In total, the survey took approximately 45 hours including transits and occasional holding patterns from ATC. This compared to a similar number of hours for flying 12.5cm imagery of the region the previous year using a frame based camera system.
Processing high resolution imagery for a project of this size would normally be very labour intensive and time consuming, to undertake aerial triangulation, mosaicing and finalising. However, the A3 Lightspeed Processing System automated many of these tasks and reduced the amount of manual effort by approximately 75%, delivering huge time and cost savings. Geosense was able to process all of the imagery rapidly and deliver the finished accurate and seamless imagery to the client within three months of starting the capture. The final delivery, consisting of a seamless, ortho-rectified mosaic of the entire CoCT area, is now in CoCT’s central GIS system and used throughout the organisation.
“This is probably one of the largest high resolution surveys ever undertaken to my knowledge” says Matt Murphy, Managing Director of Geosense. “The A3 system allows CoCT to regularly map its rapidly changing environment at very high resolution on an on-going basis, and deliver the imagery quickly so that it can be deployed across all their operations.”
VisionMap LLC is a U.S. subsidiary of VisionMap LTD., a leading provider of state-of-the-art mapping systems. The company’s A3 system is a coupled camera and ground processing system that covers extremely large-scale areas and provides accurate high-resolution imagery in RGB and NIR bands.
A3’s coverage of 60,000 pixels across track is unmatched by any other camera, and it typically acquires thousands of square miles of images per day. The system’s design allows for flexible operation at altitudes between 3,000 and 30,000 feet (1.5 inch to 1 foot GSD). The A3 LightSpeed processing system turns around raw data quickly, processing thousands of square miles daily. A3’s output products include aerial triangulation, DSM, orthophoto mosaic, and stereo models.
VisionMap’s systems reduce operator costs, enable rapid completion of statewide projects, and increase mapping and surveying project efficiency. VisionMap’s systems are used by two leading U.S. mapping companies, and an additional 20 systems operate worldwide.
Typical applications include NAIP projects, visibility mapping, and high-resolution orthophotos. The flexible A3 camera may be installed on a very wide variety of platforms. A3 LightSpeed can process outputs without controls or DGPS stations for reduced cost and faster turnaround time for rapid response applications.
VisionMap LLC is proud to provide full service support and timely maintenance services to customers in the United States, Canada, and Latin America markets. For more information please contact email@example.com
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Contact: Tim Leary, VP Business Development
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