The three main products and services from Racurs are its photogrammetric suite Photomod; creating maps and orthophotos from aerial and satellite images, and resale of GeoEye-1 and SPOT satellite imagery. Since its inception in 1994 Photomod has evolved into a complex system with many facilities for simplifying and speeding up photogrammetric operations. Some functions are deeply entrenched in the software and so not widely used by operators. The company's Alexandra Kiseleva revealed how to use them.

Photomod
User friendliness of DEM creation has been improved in version 5.0 by embedding predefined settings for the most common terrain types, such as urban, hilly and mountainous. The area-based matching technique using correlation can now cope with linear features which were problematic for earlier versions. Included also are algorithms for fast creation of dense DEMs which are next filtered to coarser grids. This seems a waste of computation power, but the seemingly redundant data plays a vital role in enhancing accuracy, removing outliers and thus improving reliability. To further increase accuracy and reliability, and to support fully automatic DEM production, feature-based matching algorithms are under construction.

Linear interpolation of TIN models has been in use for a long time for creating contours, but this method may produce frayed contours that may even intersect and thus require time-consuming manual editing. Dr Andrey Sechin, scientific director and physicist by training, presented a solution, now included in version 5.0, based on thin plate elasticity theory, which produces smooth, non-intersecting contours (Figure 1).

Earth Observation
In the time between the first Racurs conference and its tenth anniversary, 770 satellites have been launched, and around 1,220 will be rocketed into space over the coming decade (source: Euroconsult); forty of these will be low-orbiting earth-observation satellites, one of which is GeoEye-2. Weighing over 2,000 kilos and scheduled for launch in late 2012, this satellite will capture the Earth's surface with a Ground Sample Distance (GSD) of 25cm at nadir, going down to 36cm off-nadir. But as with GeoEye-1, (launched in September 2008; GSD 41cm), US government restrictions enforce re-sampling to 50cm. GeoEye is 84th on the list of ‘100 Fastest-Growing Companies' in Fortune Magazine 2010, its position attributable among other things to annual growth of more than 15% over the last three years. At present GeoEye-1 imagery covers around 10 million km2 of the total 17 million km2 of Russian territory; 4.1 million with less than 30% cloud cover and 3.5 million with less than 15%. Russia itself cherishes impressive space ambitions and is developing an earth-observation constellation aimed at mapping its entire territory.

The constellation, already approved by the Russian presidency and due for launch in 2015, will consist of two optical and two radar (x-band) satellites orbiting at a height of around 570km, and will act as a basis for geo-information provision for the whole of Russia. One issue still to be solved is transmission of the huge amount of data to ground stations. The imagery will have GSDs of 50cm and 3m. Radar is still a niche market in Russia, mainly due to a lack of specialists. Digital Globe presented major applications of WorldView-2, orbiting at an altitude of 770km and launched in autumn 2009. The eight spectral bands of this 50cm GSD imagery bring many benefits (Figure 2). The yellow band makes colour appear more natural and the additional near infrared band allows discrimination between vegetation types such as irrigated (parks) and non-irrigated grasslands. The ultraviolet band allows better differentiation of features in coastal zones.

Freebird
It is curious how new developments in technology receive poetic names when put on the market. Ambiguity resolution, the search for the correct number of integer cycles, requires continual locking onto the signal from each GNSS satellite and thus limits both aircraft banking angle to a flat turn, and distance flown from reference stations. Tight computational coupling between GNSS and inertial navigation measurements through Kalman filtering does abnegate the need for nonstop lock. The benefits are sharper turns, improving flight economy up to 25% and more flexibility in survey planning (Figure 3).

So, the marketers at Leica Geosystems must have thought, let's call it Freebird! The sensor elements of Leica's ADS80 have been doubled from 12,000 to 24,000, enabling flying at double the height without compromising GSD.

To store all these data a new 480GB solid-state memory unit is on offer. Novel photogrammetric systems often originate in military applications, as did the A3 Digital Panorama Camera from Visionmap, a company founded in 2004 in Israel. Two cameras rotate in sync across the flight line, shooting array images, nadir and oblique. The long focal length enables data capture at high altitude; in one day, 5,000 km2 can be captured with 15cm GSD.