Valtus hosts a vast variety of geospatial content. The Valtus library and our partnerships with leading content collectors deliver the high-quality foundational data our customers depend on.
Orthophotos are aerial photographs (or digital versions of these photographs) that have been 'orthorectified' using ground elevation data to correct displacements caused by differences in terrain relief and camera tilt. The process endows an orthophoto with the accuracy of a map. Because aerial photographs show ground textures in much greater detail than maps, orthophotos are useful for updating maps and for studying surface features.
For determining elevations, LiDAR ('Light Detection and Ranging' or 'Laser Imaging Detection and Ranging') is more accurate and cost-effective than other methods of photogrammetric compilation. A laser beam from an aircraft platform scans the ground perpendicular to the line of flight, and the laser returns, or reflections, from the ground and foliage are processed to determine the ground elevations. As LiDAR penetrates tree cover, it provides the most accurate ground definition possible.
Vegetation can be distinguished using remote sensing data from most other (mainly inorganic) materials by virtue of its notable absorption in the red and blue segments of the visible spectrum, its higher green reflectance and its very strong reflectance in the near-IR. Different types of vegetation show often distinctive variability from one another owing to such parameters as leaf shape and size, overall plant shape, water content and associated background (e.g., soil types and density of vegetative cover). Even marine/lake vegetation can be detected.
For its ability to collect imagery in areas of difficult access anywhere in the world, satellite imagery has played a significant role in earth observations for many years. Using conventional digital imaging technology, satellites obtain imagery for a required area and transmit that imagery to receiving stations where it is recorded and processed.