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In analogy to the mapping of forests from above using drones, the idea behind “inverted mapping” is to map the canopy structure from the ground. As in the case of the aerial mapping, the canopy is ‘scanned’ by shooting a set of vertical oriented overlapping photos which are then processed using photogrammetric methods.
While aerial mapping delivers data such as 3D point clouds, Digital Surface Models and ortho-maps of the visible part of the upper forest structure, data which can be used, for example, to calculate the tree height or detect changes, the “inverted mapping” – using the present technique, which is still in development – is able to deliver a map of the canopy coverage with a high level of detail. This information can be used, for instance, to calculate canopy closure or single crown parameters
The “inverted mapping” method represents a good solution to create detailed canopy coverage maps. It is a straight forward, quick and low-cost option to produce data of crown closure and distribution in a forest.
The first experiments with the “inverted mapping” were carried out on the experimental fields of Nassau in German Saxony on behalf of Sachenforst. An area of approximately 1 ha was covered. Around 2000 photos distributed over a grid of 3 m by 3 m were taken manually.
These images were processed using photogrammetric methods generating 3D information (point clounds) used subsequently to create an ortho projection of the canopy distribution. The resulting high resolution maps were classified and analyzed giving place to the images presented here.
We are planning to publish a description of how the method works on our site soon. We will include a detailed explanation of every step and discuss about the limitations, challenges and potentials of the method. So, if you are interested in learning more about “inverted mapping”, stay tuned.
One of a series of approx. 2000 photos taken to map the canopy coverage.
Canopy coverage maps produced using photogrammetric methods. The upper image shows the distribution of the canopy structure. The lower image shows the respectively calculated degree of coverage for cells of 1.5 m by 1.5 m. The darker the blue value the higher the coverage level for that cell. The images correspond to an area of approx. 0.3 ha.