Two workflows in one view
Local rasters: load two images and align source B manually using translation, rotation and scale.
Georeferenced basemaps: choose any two integrated map sources. Their navigation stays synchronized, so comparison starts immediately.
Typical workflow
- Open Compare.
- Select Source A and Source B.
- For basemaps, simply navigate to the area of interest.
- For two local rasters, adjust source B until the features line up.
- Inspect differences with Opacity or Swipe.
Need coordinates and error metrics?
Switch to Georeferencing and add ground control points. GeoCalque can then calculate an affine, projective or Thin Plate Spline transformation and report residuals/RMS error.
Compare IGN LiDAR HD with aerial imagery or historical maps
GeoCalque now exposes IGN LiDAR HD DTM, DSM and height-model hillshades directly in Quick Comparison, together with the experimental LiDAR Terrain and Above-ground map products.
A particularly useful workflow is to compare current IGN aerial imagery with the LiDAR HD DTM. Swipe or opacity can help distinguish present-day vegetation from persistent terrain features such as old tracks, banks, ditches, terraces or platforms.
Read about the IGN LiDAR HD layers in GeoCalque
You can also enable Point info on the map to query selected public datasets — cadastral parcel, BRGM / InfoTerre geology, GIS Sol / INRAE soils and other optional layers — without changing the visible basemap.