An assessment of the utility of a non-metric digital camera for measuring standing trees
Images acquired with a commercially available digital camera were used to make measurements on 20 red oak (Quercus spp.) stems. The ranges of diameter at breast height (DBH) and height to a 10 cm upper-stem diameter were 16-66 cm and 12-20 m, respectively. Camera stations located 3, 6, 9, 12, and 15 m from the stem were studied to determine the best distance to be used with the maximum wide angle setting on the camera. Geometric mean diameter estimates from the 12 and 15 m distances were within 94 cm at any height (95% x 2 ). Though unbiased, measurement variation was found to increase with stem height. Using camera derived heights and diameters, volumes were found to be within 8% of volumes calculated using taped measurements of individual stems two times out of three - an improvement over existing DBH-height volume equations. This preliminary work demonstrates the ability of using a digital camera to acquire stem diameters and heights. Some limitations of the current technology are also noted. By combining equipment and procedural modifications with improved data flow from imagery to information, terrestrial digital imagery may revolutionize stem or even plot level data collection.