Research on doing automated forest inventories from aerial photography is carried out at The Royal Veterinary and Agricultural University of Denmark and at the Danish Forest and Landscape Research Institute. Automatic methods for obtaining the stem count of spruce stands have been developed and are being tested operationally. The effort is now being directed towards inventories on the individual tree level. This talk will focus on an effort to identify the tops of individual spruce trees in forest stands from high-resolution aerial photographs. This approach makes it possible to find and position tree tops from a wide range of off-nadir viewing angles.
Performance is evaluated by use of data from a thinning experiment in Norway spruce.
It turns out that images where the trees are backlit by the sun are especially well suited for this approach. Both of these resources are accessible via Netscape. This talk will demonstrate them and convince you that they are worthwhile using. The projective transformation onto the retina loses the explicit 3D-shape description of a moving object. This has led to the conjecture that these cells provide a local measure for the directional derivatives of the 2D-velocity field.