Data — High-resolution CIGAL Orthophotography (20 cm) color (BD ORTHO IGN HR 2015) — Alsace and Kehl

L'ORTHO HR is a collection of corrected color orthophotography digital mosaics in Lambert 93 projection. It is produced by the 'IGN. It results from an analog aerial shooting dating from summer 2015 orthorectified in Lambert 93 projection and then assembled. It covers all the departments of Haut-Rhin, Lower Rhine and Kehl. The native resolution of the image (pixel size) is 20 cm. This project received funding from the Alsace Region, the Haut-Rhin Department, the Lower Rhine Department, Europe (FEDER) and the French State (FNADT). Data are available under open license (Etalab). __Origine__ This product corresponds to the specifications as described in the content description of March 2014 — BD ORTHO® HR and the delivery description of June 2014 — BD ORTHO® HR, subject to the adaptations and technical details of the Annex to the grant agreement of 10 September 2015 (Actions 1 and 2 below). The descriptions are in the associated resources as well as the flight plans, the Moisaique graph and the checks carried out by the CIGAL partners during the recipe phase. Action 1: aerial shooting Geographical Right of Way: the whole territory of the Alsace region and the City of Kehl with a buffer zone of 500 meters on French territory and 1 kilometre outside. Acquisition of digital color images with a native resolution of 20 cm. Maximum cant on buildings less than 25 %. Solar angle greater than or equal to 40° for the so-called agglomeration areas and 30° on the other areas. Aerial shooting between 15 May and 15 September 2015, if weather conditions permit. Action 2: color digital orthophotography Ortho-rectification will be carried out using the most accurate available Digital Terrain Models. The ortho-image will be produced in projection Lambert 93 and Lambert 93 (zone 7) CC48. The ortho-image will be delivered in slabs of 1 kilometre side depending on the round kilometers of the projection. The file formats will be: JPEG 2000; Optimised JPEG 2000; TIFF (Tagged Image File Format) 24 bit " Real colors " RGB, uncompressed, not tiled. The georeferencing of slabs will not be integrated into the image file. It will be done via.twf georeference files (Tiff Word File) and.tab (MapInfo) The cut tiff and jp2000 e100 is in 1 km x 1 km, the jp2000 e80 (optimised) is in 5 km x5km. In optimised mode, JPEG2000 compression is done at the nominal compression rate of 20. The actual compression rate is chosen so that no colorimetry difference is visible at zoom 1 (i.e. optimal display of data based on resolution) between the uncompressed image and the compressed image. The colorimetry is thus generally preserved, with in particular the absence of creation of parasitic colors, blurry and loss of visible information. This compression does not degrade the geometry. The radiometry is the one proposed by the IGN, the CIGAL partnership makes available as an attachment a tutorial to rework the colors (Eurometopole de Strasbourg). __ Partner Organisations__ Cigal, National Institute of Geographical and Forest Information — IGN __Links annexes__ * [content description](http://professionnels.ign.fr/sites/default/files/DC_BDORTHO_2_ORTHOHR.pdf) * [delivery description](http://professionnels.ign.fr/sites/default/files/DL_raster_ORTHO.pdf) * [tutorial modify radiometry](https://www.geograndest.fr/portail/node/785) * [download guide](https://www.geograndest.fr/portail/node/787) [See this sheet on geo.data.gouv.fr](https://geo.data.gouv.fr/fr/datasets/82084758feb862b4014c5243beaf744cdedb0497)