Matthew F. Winn

An assessment of the utility of a non-metric digital camera for measuring standing trees

Abstract 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 ±4 cm at any height (95% χ2). 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.

Automated Grading, Upgrading, and Cuttings Prediction of surfaced dry hardwood lumber

This paper concerns the scanning, sawing, and grading of kiln-dried hardwood lumber. A prototype system is described that uses laser sources and a video camera to scan boards. The system automatically detects defects and wane, searches for optimal sawing solutions, and then estimates the grades of the boards that would result. The goal is to derive maximum commercial value based on current market prices. This paper presents the results of a recent empirical test in which the systems grading decisions are compared with those assigned by a human expert. We also assess the potential of cuttings from the lumber by board grade. The test involved 86 yellow poplar boards and 90 red oak boards. The automated system assigned higher grades for 17% of the boards, and it assigned lower grades for 43% of the boards. The main cause of disagreement was the presence of stains on the board, both natural and mechanical, which were occasionally classified by the scanning system as defects. The system also recommended additional edging or trimming on 42% of the boards to increase the grade and value of the boards. Overall, the automated system performed well on typical cases of planed and dried boards.