Orthodox photographs of the City of Helsinki

The City of Helsinki’s ortho aerial photographs are a series of different orthodox photographs photographed in different years.The entire area of Helsinki is photographed from the air at regular intervals. The descriptions are carried out systematically in such a way that a part of the city is always photographed annually. The series also covers oblivion photographs and false-colour aerial photographs that have been photographed in different years.In recent years, laser scanning has been done systematically in connection with aerial photography. Rectified ortho aerial photographs are produced from aerial photographs, which are positioned in the ETRS-GK25 (EPSG:3879) level coordinate system (previously in the separate coordinate system of the City of Helsinki).The update is annual and the material is produced at different scales. Ortho aerial images are produced with different precision levels (80 cm, 50 cm, 40 cm, 25 cm, 20 cm and 5 cm/pixel). The most accurate aerial photographs (5 cm) described for mapping purposes are photographed in spring and more generalised aerial photographs of the surface are usually photographed in summer. Ortho aerial image (orthopic) is a rectified aerial image that depicts the surface perpendicular to the air and corrected for a plane map.Oblique aerial image is a diagonal aerial image of the surface of the ground. Laser scanning data is a three-dimensional dot-like data describing the surface of the ground and objects on the ground surface, which can be used to produce an accurate elevation model from the ground surface. Data is available from WMS and WMTS interface with levelers Orthodontics_2019_5cm Orthodontics_2018_5cm Orthodontics_2017_8cm Orthodontics_2017_20cm Orthodontics_2016 Orthodontics_2015_20cm Orthodontics_2014 Dangerous orthodontics_2017_20cm Aerial view_2015_20cm