Description
These are black and white orthophotos made from frames of the flight “ALIFOTO 1975”. To realise this product were scanned about 11,000 frames of the aerial flight “ALIPHTO 1975” in black/white with average scale 1:15,000. The starting material is organised in rolls of negative on gloss. The entire project area was divided into blocks and the aerial triangulation was performed on each individual block, to facilitate calculations and to allow more control; accurate of the results. The subdivision into blocks took into account the topography of the ground, the plane of the analogue flight and, above all, the membership of the frames to the same roll, to ensure uniformity; in the transition from scanning to triangulation, without interruptions or seams, and the breakdown of the final ortorectified product. The scan of all negatives took place with photogrammetric scanner with geometric accuracy of ± 2microm and high radiometric performance with dynamic “range” of 12bit and “density range” at 3.4D or greater. The scan was performed with real optical resolution of 1200dpi, resulting in the pixel size of the digital image of about 30 cm. The individual scans were saved in 8-bit TIFF format. The orthorectification operation was carried out using as a digital model of the terrain the DTM Regione Lombardia with sampling step 20 m.
Resources
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https://www.cartografia.servizirl.it/arcgis2/services/BaseMap/ortofoto1975/ImageServer/WMSServer? |
Tags
- mappe-e-foto-aeree-storiche
- ortofoto-1975
- cartografia-di-base-e-ortofoto
- eu
- alifoto