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Georeferencing using QGIS (Scanned maps, aerial photos, ..)

Georeferencing using QGIS (Scanned maps, aerial photos, ..)



Georeferencing using QGIS Scanned maps, aerial photosMost GIS projects require georeferencing some raster data. Georeferencing is the process of assigning real-world coordinates to each pixel of the raster. Many times these coordinates are obtained by doing field surveys - collecting coordinates with a GPS device for few easily identifiable features in the image or map. In some cases, where you are looking to digitize scanned maps, you can obtain the coordinates from the markings on the map image itself. Using these sample coordinates or GCPs ( Ground Control Points ), the image is warped and made to fit within the chosen coordinate system. In this tutorial I will discuss the concepts, strategies and tools within QGIS to achieve a high accuracy georeferencing.
How to determine datum and coordinate system for old maps.


Georeferencing in QGIS is done via the ‘Georeferencer GDAL’ plugin. This is a core plugin - meaning it is already part of your QGIS installation. You just need to enable it. Go to Plugins ‣ Manage and Install Plugins and enable the Georeferencer GDAL plugin in the Installed tab.

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