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Archive for June, 2012

County of Scotland (North Carolina, US) GIS Cartography

2012/06/20

One more video  i recorded long ago on geoprocessing Cartography. Landuse, DTM, etc.
Hope you like it.

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Creating DEM/DTM

2012/06/19

It was 2007 when i finished my master’s degree and wanted to show some videos of procedures. At that moment in time i wanted to find a job -any job- involving GIS and i finally found it dealing with the Geovisualization department within a GIS company… now i happen to deal with DEMs. DTM, etc on a daily basis which is great!!. I hereby show you that video.

Hope you like it,
Regards,

Alberto

Airmap: UAV aerial surveying technology

2012/06/10

The most efficient way to monitor our environment is from above. Traditionally, aerial photography and mapping is a costly and time consuming business. However, by using our UAV technology, we are able to offer a cost and time effective solution for your aerial photography and mapping needs. Obtaining high resolution Orthorectified image mosaics and Digital Elevation Models has never been this easy.

Q: Can the UAV fly in all weather conditions?

A: Technically, our UAV can fly with winds up to 7 m/s (i.e. moderate breeze), in low-visibility conditions, or even at night. Although light rain will usually not affect its flight characteristics, the swinglet is not water-proof and should therefore not be used when raining or snowing. For best image quality, the UAV should be used on clear days with light wind (up to 5 m/s, i.e. a normal breeze is fine).

Q: What are the specifications of the camera used in the UAV?

A: The UAV is equipped with a 12 MP compact camera with a focal length of 24 mm (in 35-mm equivalent). The resulting ground resolution is adjusted by choosing an appropriate flight altitude (typically between 50 and 1000 metres above ground) and will range from 2 to 40 cm/pixels.

Q: What is the area that can be typically imaged during one flight?

A: This depends on the flight altitude (and thus the ground resolution): At 140 m (ground resolution of 5 cm/pixel), one picture covers 0.03 square km (3 ha, 7 acres) and one flight covers up to 1.5 square km (150 ha, 370 acres). * At 280 m (ground resolution of 10 cm/pixel), one picture covers 0.12 square km (12 ha, 29 acres) and one flight covers up to 4 square km (400 ha, 990 acres). * At 840 m (ground resolution of 30 cm/pixel), one picture covers 1.07 square km (107 ha, 265 acres) and one flight covers up to 10 square km (1000 ha, 2470 acres).

Q:What are the flight performances of the UAV?

A: The UAV has a flight endurance of about 30 minutes with a fully charged battery. The endurance is reduced with wind, frequent altitude changes or very low temperatures. The cruise speed is 10 m/s (36 km/h, 22 mph). The climb rate is about 3 m/s. The maximum wind speed is 7 m/s (25 km/h, 16 mph), which corresponds to a moderate breeze. This includes a safety margin to allow the UAV to fly back home automatically when strong wind is detected by the autopilot.

Q: How many images can be taken during one flight?

A: When photos are triggered at maximum rate (every 3-4 seconds), the number of images in one flight can reach 400. The provided onboard memory card has more than enough space to store such a number of images at full resolution.

Q: What level of accuracy should be expected?

A: The accuracy of the orthomosaics and the digital elevation models (DEM) strongly depends on the flight height, lighting conditions, availability of textures, image quality, overlap, and type of terrain. In standard conditions (flying at 100-150 meters above natural terrains with 50 to 70% image overlap), a relative accuracy of 10 cm and an absolute accuracy of 3-5 meters is obtained without the use of Ground Control Points (GCP). However, GCP’s can be introduced, reducing the absolute error to the level of a few centimeters.

Interested? Visit http://airmap.co.za