Classical orthophoto has some disadvantages, which are eliminated in the process of generating true orthophoto. True orthophoto is generated from aerial photographs and digital surface model (DSM) in a process of enhanced orthorectification. DSM represents the earth's surface and includes objects like buildings and bridges. DSM data are usually stored in one of the vector file formats. In the past, DSM data were mostly acquired through process of stereoscopic data capture, but with a development of airborne laser scanning many different methods for automatic building extraction from lidar data are now available. In graduation thesis a simple algorithm for extracting building heights from lidar data was developed. In the first, theoretical part main differences between classical and true orthophoto are shortly presented as well as differences in their production line. In addition, main principles of airborne laser scanning are described. The second part treats the practical work. It contains presentation of developed algorithm, its realization in ESRI ArcGIS and evaluation of the final orthophoto results produced with different digital surface models.
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