N.B. per utenti Italiani: questo sito è dedicato alla versione internazionale di CorrMap in Inglese. la versione Italiana è disponibile dal sito dedicato

Geo-referencing and Calibration of Maps

Get real geometric information from your maps

The availability of maps as raster image files gives a great benefit to professional users who need to obtain geometrical information from them (coordinates, distances, etc.). The advantage is not simply to avoid the inevitable limits of a manual inspection of the original paper map (time limited inspection, possible errors due to “human” reading, etc.).

A raster map file gives you the capability to adopt some sophisticated mathematical algorithms (transformations) which allow you to reach a precision up to 10 times more accurate than a manual inspection. This is because a raster map is a file and, as such, it can be conveniently manipulated and modified by specific software.

CorrMap does not only perform the map geo-referencing, i.e. re-position an old map over a new one or over a real photo, like other software or web services do; it also rectifies your old maps removing the deformation to which they have been subjected due to the wearing effect of time.

In fact, without this feature you still are not able to retrieve the correct geometrical information from your raster maps. CorrMap can calibrate and rectify any type of map available as a raster image file, this is why it was developed, with its following 6 transformations:

  1. Affine: assigns real map coordinates, rectifies the orientation to the North and transforms from pixels to real measurement units.
  2. Grid: based on grid lines, assigns real map coordinates by correcting the deformation of single map sections.
  3. Barycentric: for maps with no grid points, assigns real survey coordinates, rectifies the orientation and transforms from pixels to real measurement units.
  4. Homography: for aerial photographic images, rectifies the map with reference to real surveyed points.
  5. Rubber-Sheeting: corrects randomly deformed maps with reference to new maps provided with a grid of control points.
  6. Trilateral: corrects old maps with reference to a triangulation on real surveyed points.


All the transformations performed by CorrMap export the final result in the most popular file formats, such as GeoTIFF, TWF, DXF, XY, XLS, DOC, in order to let the user make the most use of the geo-referenced rectified map.

Continue reading: Why do raster maps need to be geo-referenced ? ››