Spatial Tree Mapping Using Photography

Stem maps describing the spatial location of trees sampled in a forest inventory are used increasingly to model relationships between neighboring trees in distance-dependent growth and yield models, as well as in stand visualization software. Current techniques and equipment available to acquire tree spatial locations prohibit widespread application because they are time-consuming, costly, and prone to measurement error. In this report, we present a technique to derive stem maps from a series of digital photographs processed to form a seamless 360 degrees panorama plot image. Processes are described to derive distance from plot center and azimuth to each plot tree. The technique was tested on 46 field plots (1,398 sample trees) under a range of forest conditions and compared with traditional methods. Average absolute distance error was 0.38 +/- 0.44 m, and average absolute azimuth error was 2.3 +/- 2.5 degrees. Computed average horizontal accuracy was 0.40 +/- 42 m, with 85% of measured trees being within 0.5 m of the field-measured tree location.