Nicholas method is about transforming coordinates from a CRS to another one.
QGIS also has the possibility of enable on the fly CRS transformation. In both cases you should know the CRS for vectorized historic map. QGIS will do the best to generate a custom CRS and associate to your data but it does not work all the time. Do you know the CRS for vectorized historic map? To be accurate during coordinate transformation you need to associated the original data with a CRS. We had an issue with not georeferenced data. When we loaded the vectorized data, QGIS assigned a weird CRS. After we <<save as>> to GRS80 the area was shifted. We knew the area was somewhere in Vancouver and the area was over a stereographic projection. I knew the point of tangency and I created a custom CRS which was associated to my original data. After this tweak we were able to overlay precisely the area where it belongs. I hope this helps. Marian From: Qgis-user [mailto:qgis-user-boun...@lists.osgeo.org] On Behalf Of Nicolas Cadieux Sent: June-07-18 9:54 PM To: David Hochfelder Cc: qgis-user@lists.osgeo.org Subject: Re: [Qgis-user] Converting X Y Coordinates to Latitude/Longitude Hi David, I’am an archaeologist working in Québec. If you vectorized the map in a local CRS, all you need to do is do a « save as » and change the CRS (coordinate reference system) that is in Longitude Latitude. If your map is not georefenrenced (that is, you just scanned the map and did not use a CRS, that is more complicated but not impossible. I usually fixe that do in a CAD but I am sure you can do it in QGIS. We could talk if you want and I could help you out figured the next steps and steps to avoid this problem (like georefereing the raster map before you start) .Send me an email directly. You could look at this also. https://gis.stackexchange.com/questions/136817/qgis-moving-the-layer-all-features-using-vector-affine-transformation Nicolas Le 7 juin 2018 à 20:49, David Hochfelder <dhochfel...@albany.edu<mailto:dhochfel...@albany.edu>> a écrit : Hi All, I am new to QGIS, so this may be a newbie question easily answered by the more experienced. I'm working on a historical GIS project to remap an area of Albany, NY demolished for urban renewal in 1962. I've succeeded in vectorizing a historic map of the area (~1960), but the coordinates are not in lat/long form. I see that there are plugins for converting tables of specific coordinates, but I want to convert the entire map continuously. This area no longer exists--all the buildings and streets were cleared for the Empire State Plaza state capitol complex. My end goal is to use the rectified map as a way to geotag historic photographs of particular buildings. Is there a way to convert the coordinates in a continuous fashion for the entire region? Thanks for your help. Dave Hochfelder David Hochfelder Associate Professor History Department Social Science 060B University at Albany, SUNY Albany, NY 12222 518-442-5348 _______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org<mailto:Qgis-user@lists.osgeo.org> List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user ________________________________ This electronic message, as well as any transmitted files included in the electronic message, may contain privileged or confidential information and is intended solely for the use of the individual(s) or entity to which it is addressed. If you have received this electronic message in error please notify the sender immediately and delete the electronic message. Any unauthorized copying, disclosure or distribution of the electronic message is strictly forbidden. NAV CANADA accepts no liability for any damage caused by any virus and/or other malicious code transmitted by this electronic communication. Le présent message électronique et tout fichier qui peut y être joint peuvent contenir des renseignements privilégiés ou confidentiels destinés à l’usage exclusif des personnes ou des organismes à qui ils s’adressent. Si vous avez reçu ce message électronique par erreur, veuillez en informer l’expéditeur immédiatement et supprimez le. Toute reproduction, divulgation ou distribution du présent message électronique est strictement interdite. NAV CANADA n’assume aucune responsabilité en cas de dommage causé par tout virus ou autre programme malveillant transmis par ce message électronique.
_______________________________________________ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
