While the newly digitised baftlespace brings new promises in terms of shared situational awareness and synchronized manoeuvres, the fact remains that Nato went out to Afghanistan with Soviet paper maps, and operations in Africa are still being conducted with poorly-detailed country-wide maps or obsolete terrain descriptions. In this first part of Geospatial Information series Armada's C4ISR editor analyses the technologies and tools required to build the foundation layer of current network-centric operations.
The digital age has brought a new horizon to geomatics. The word, coined in French-speaking Canada in the early 1980s, describes the contribution of digital technologies to environmental survey and analysis; geomatics encompass surveying and cartography, but also photogrammetry and remote sensing, as well as geospatial information systems (GIS) and Global Positioning System (GPS) technologies.
One could have thought that after a few centuries of charting, surveying the Earth was nearing to a close. Quite on the contrary, this endeavor is permanent, as our environment continuously evolves (think of ice caps, coastal areas or deforestation), and man adds new features to topography. Most importantly, requirements for accuracy have soared, as precision navigation and guidance open new dimensions in fine-grain Earth surface analysis, from route clearance against roadside bombs to urban combat, not to mention navigating the largely uncharted ocean bottoms.
1 DATA COLLECTION: ACCURATE AND AGILE SENSORS
While surveying trade has not disappeared, the surveying tools have changed dramatically. Today's military topographic teams thus deploy with state-of-the-art ground sensors and software. Ground measurement sensors gradually integrate laser technologies for highly accurate ranging, but above all the very location of measurement units is immensely enhanced by the latest global navigation satellite systems like the GPS and the Glonass, joined since 2014 by their European and Chinese counterparts respectively known as Galileo and Beidouns. In some areas of the world, differential GPS services allow pinpoint ground location. The latest generation of Trimble Pro series of receivers, for example, subscribe to Egnos (European Geostationary Navigation Overlay Service) to offer up to sub-meter accuracy, while ensuring maximum use of available satellites and some resistance to atmospheric and environmental degradations. The resulting measurement of ground control points, essential to topographic survey and map-making, is near error-free. US Army engineering topographic survey teams thus deploy with the Northrop Grumman Enfire kit.
In hostile or remote areas though, where safety is an issue with the added difficulties resulting from multiple interferences from foliage or buildings for example, it has led the military to develop remote sensing devices. The fast development of aerial photography has allowed to capture vast expanses of sea or land, while multi-point triangulation techniques gave access to accurate location, free from ground interference. In addition, oblique or stereo imagery added terrain elevation information. Today, the proliferation of sensors and digital image processing technologies have boosted photogrammetry, opening new grounds for data integration across the electromagnetic spectrum, combining laser, infrared, optical and radar wavelengths for unparalleled capture of terrain data not only in daytime and nighttime but also above clouds. The Swiss Leica Geo Systems is famous for its airborne imaging sensors.
The Leica ADS80 airborne digital sensor offers a high-resolution mode for orthophoto production, with swath width of 24,000 pixels. It comes with a flight management and control system software, computing aircraft dynamics against a software sensor model to minimise flight and atmospheric distortions. Multi-triangulation measurements determine camera's position in x, y and z when the picture is taken to automate production of large mosaics of the surface covered. An extension to these capabilities has arrived to accommodate the growing use of video sensors onboard surveillance drones.
Video offers various advantages, not only in terms costs, but also in terms of data availability, which can be real time. Simactive, a French Canadian developer of photogrammetry software since 2003, has recently unveiled a new version of its Correlator 3D tailored for small-format drone sensors. The ultimate refinement in aerial remote sensing though has come from active sensors in the non-visible range in the form of the lidar (Light Detection And Ranging). This provides a laser-based method of scanning the Earth that is particularly suited to characterise micro-elevations. Initially developed to measure forest canopy or coastal erosion, the lidar has become a primary sensor to generate digital elevation models (i.e. Earth elevation augmented by vegetation cover and man-made objects).
The space age took overhead imagery and remote sensing to new altitudes. Since satellite images are less prone to atmospheric interference and have predictable distortions along orbital paths, space reconnaissance has become the preferred method of collecting data on huge territories worldwide--free from airspace sovereignty. The early remote sensing satellites of the 1960s were thus the most valuable strategic assets to map adverse territory and manage crises, until digital cameras and commercial satellites brought this capability to the larger public. The US National Geospatial Agency began to place large contracts with commercial imaging satellite operators, until costs dropped in 1999 when Landsat satellite data became copyright free. Google began to democratise "space maps" from the mid-2000s, initially providing 30 metre resolution, multi-spectral band Thematic Mapper Landsat imagery, then moving on to...