LIDAR

Aerial photograph of a forest. Useless for mapping paths and forest road located there

LIDAR of a forest, in exactly the same location. May require survey to distinguish roads and paths from streams and ditches, but after that allows extremely accurate tracing of features. This ISOK Cien layer is available in Poland and covers entire country

LIDAR is a method for measuring distances by illuminating the target with laser light and measuring the reflection with a sensor. Differences in laser return times and wavelengths can then be used to make digital 3D model of the target. In OpenStreetMap context primary use is airborne scan of terrain.

The scan results of terrain are typically presented as a shaded relief imagery, often in grayscale.

LIDAR can penetrate tree cover and be so accurate that one may map paths based on a shape of ground.

As all sources, only what is released on a compatible copyright can be used.

Some countries are fully covered by high quality LIDAR available on a compatible licenses.

External links

• Lidar article at Wikipedia, with info about also other uses