- SPECIAL REPORTS
- THE MAGAZINE
Graz, Austria - The Microsoft UltraCam business unit announced a 210mm lens for the UltraCam Eagle digital aerial camera system. The UltraCam Eagle was introduced in May 2011 as a multi-cone digital photogrammetric camera that offers an exchangeable lens system with 80mm (standard) and 210mm (tele) lenses. After extensive flight testing, the 210mm lens is now being released.
The 210mm lens captures the same high dynamic, high quality, detailed imagery as other UltraCam systems, with the added benefit of flying at high altitudes, e.g., 5 cm imagery at a 2,000 m altitude. This allows data collection to take place over restricted airspace, such as cities, without applying for special permits. Despite the increased distance to the ground, the results of the AT and dense matching tests support Microsoft’s belief that the base/height ratio is not the only important factor with respect to accuracy. The 210mm lens returns accurate geometry even from a high altitude. Also, the small field of view minimizes building lean for tall buildings, allowing full utilization of the 20,010 pixel swath width for ortho image production. Occlusions are minimal even for narrow streets or alleys.
Users also benefit from the greater radiometric dynamic produced by the UltraCam Eagle. When mapping at high altitude, the atmosphere can lead to a loss of contrast and color shifts. By capturing imagery in “Raw format” with the 210mm lens, more bits-per-pixel of image dynamic are collected and saved. During processing it is possible to restore the colors without losing any data, and the high image dynamic allows for correction of haze, hotspots and other artifacts, such as color shifts caused by the atmosphere. Due to this technology, the resulting images look more consistent and realistic.
“When compared to competing systems that use a Bayer pattern approach, the UltraCam Eagle 210mm lens demonstrates several clear advantages,” states Alexander Wiechert, Microsoft business director. “Typically a Bayer pattern CCD reduces geometric accuracy. A small error on the CCD due to interpolations sums up to a big error on the ground due to the high altitude. Also, a Bayer pattern CCD collects less than a 12-bit image dynamic, which is almost half of the image dynamic captured by the UltraCam with the 210mm and other UltraCam Eagle lenses. That lower image dynamic typically results in lower image quality as there is no leeway to correct for the atmospheric effects.”
The 210mm lens can be exchanged in a clean hangar environment by the customer’s personnel after training from Microsoft’s Support team without the need for re-calibration.