The basic processing of the laserscanner data results in an elevation model accurately describing the earth’s surface (upper edge of the vegetation, roof heights of houses etc.). Such an elevation model is called DSM (Digital Surface Model). In a further processing step the vegetation and buildings can be removed to produce an elevation model of the terrain surface DTM (Digital Terrain Model).
The high measuring density and small raster width of the elevation models permits further evaluations, such as the vectorization of the buildings and the extraction of structural elements such as trenches, break lines or dams.
The TopoSys airborne laserscanner and RGB/NIR line scanner produces a multitude of diverse measured values from which elevation models and true ortho images are generated. The data is rendered in a form (formats, file sizes) ensuring simple handling by the client.
The majority of our clients have decided for a data format which TopoSys has been offering as standard for some considerable time. Other data structures or data evaluated for a special application can also be supplied, but require a separate agreement. 
The elevation values are calculated in a metric, orthogonal system with local coordinates. Large areas are divided into smaller, square subareas. A grid with equidistant rows and columns is superimposed on each subarea. A representative elevation is assigned to each grid element. Each grid element (x, y coordinate) can be directly addressed and the associated elevation can be output. This data structure can be processed by a large number of application programs (ArcGIS, ERDAS, PCI, etc.). Airborne data acquisition covers significantly more measured values than are required for the further processing. For this reason different elevation models can be calculated. In so doing, distinction can be made between first echo (FE) and last echo (LE) or high and low values.