The task was to determine the volume of several stockpiles of peat on behalf of a major bio-fuel company. The typical size of the cone-shaped piles were about 15 m hight and a radius of 30 m, thus being much too small objects for conventional aerial survey. Due to the nature of peat production the piles were dispersed within a 5 km wide and 10 km long area. Thanks to the quick setup time and ability to load preplanned flight mission parameters it was possible to complete entire flights within 20 minutes (from arrival to departure from a site). The operational restriction to fly within visual range (800 m) usually meant that only one pile could be mapped from a specific location but occationally two or three piles could be reached from a take-off site.
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- Digital surface model shown with color gradient and sunshading
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- Orthophoto mosaic over a single pile
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- PAMS orthophotomosaic overlayed on top of the regular photo map
During the day the wind incrased in strenght and became quite strong and turbulent with (10-12 m/s on average at 125 meters altitude). However the SmartOne aircraft has excellent stability and was able to penetrate the wind eventhough it seemed to be flying sideways along the photo strips and even hovering on the same spot for short moments. In strong winds it is important to orient the photo strips perpendicular to the wind in order to avoid excessive speeds when flying downwind which might lead to missed photos since the exposure interval could become too short for the camera to cope with.
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- Detail of PAMS orthophoto with countour lines
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- Perspective view of PAMS orthophoto draped over the surface model
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- Biofuel piles overlayed with contour lines (50cm)
The image datasets were processed into high density surface models (25 cm point spacing) and orthophotomosaics (3 cm resolution) by Germatics GmbH operating the PAMS processing center. The volume of individual piles were derived by subtracting the interpolate ground surface (as digitized from the pile edge). When compared to the results of conventional ground-based GPS surveying the surface detail is more accuratly represented in the PAMS surface model as opposed to the large facets derived from the GPS points. When representing a convex shape like a cone with large facets there is an inherent risk for systematic underestimation of the volume.
