Search results
Results from the WOW.Com Content Network
The quality of a DEM is a measure of how accurate elevation is at each pixel (absolute accuracy) and how accurately is the morphology presented (relative accuracy). Quality assessment of DEM can be performed by comparison of DEMs from different sources. [29] Several factors play an important role for quality of DEM-derived products:
This is currently the most detailed and accurate method of creating digital elevation models, replacing photogrammetry. One major advantage in comparison with photogrammetry is the ability to filter out reflections from vegetation from the point cloud model to create a digital terrain model which represents ground surfaces such as rivers, paths ...
The elevation datasets are affected by mountain and desert no-data areas. These amount to no more than 0.2% of the total area surveyed, [11] but can be a problem in areas of very high relief. They affect all summits over 8,000 meters, most summits over 7,000 meters, many Alpine and similar summits and ridges, and many gorges and canyons.
The most popular way to achieve real-time, low-cost signal transmission is to use a radio modem, typically in the UHF Band. In most countries, certain frequencies are allocated specifically for RTK purposes. Most land-survey equipment has a built-in UHF-band radio modem as a standard option. RTK provides accuracy enhancements up to about 20 km ...
The post-processed measurements allow more precise positioning, because most GPS errors affect each receiver nearly equally, and therefore can be cancelled out in the calculations. Differential GPS measurements can also be computed in real time by some GPS receivers if they receive a correction signal using a separate radio receiver, for ...
For premium support please call: 800-290-4726 more ways to reach us
Nearmap's Measurable Obliques allow users to make accurate height measurements of buildings and other ground features. Users can then export these images with the measurements and annotations included, allowing multiple stakeholders to communicate with accurate detail to an entire project team.
Elevation measurement: Using fine resolution remote sensing techniques, especially Lidar and drones, to directly or indirectly (through Photogrammetry) measure the height and or shape of land cover features, and shade that elevation surface. This technique is most useful at producing realistic maps at relatively large scales, 1:5,000 to 1:50,000.