Methods of digital photogrammetry in forest management in Slovakia

The practical aspect of utilization of digital photogrammetry methods and their products in Slovak forestry is presented. We deal with the comparison of various data obtained by digital cameras, their accuracy, utilization and effectiveness for mapping. Based on presented results we summarize the main conclusions in the field of forest mapping. We also deal with the process of pan-sharpening for the preparation of image data for the interpretation and classification of forestry features. Also, the statistical characteristics of two photogrammetric projects with different geometric resolution photos (Ultracam D digital camera with ground sample distance of 10 cm and UltracamX digital camera with ground sample distance of 20 cm) from the same experimental area of the University Forest Enterprise Zvolen are described with the aim of finding an appropriate solution suitable for forest mapping. In both cases, the horizontal accuracy of the photogrammetric projects is presented. Finally, the process of true orthophoto generation and its utilization in forestry is the focus. Both experiments in this paper presented results which fulfil the accuracy standards defined by the state cadastre within the mapping of large scale maps. All projects, apart from the project of direct georeferencing, fulfilled the third accuracy class of mapping, so they can be used within cadastral mapping, land consolidations and, of course, within forested land mapping. Still, all the projects meet the accuracy requirements within the forest mapping standard, where the forestry features and forest spatial distribution units are mapped.