Angle gauge

Abstract: Materials and Methods Study Location Sample plots were located on the J.D. Irving, Ltd., Black Brook District in northwestern New Brunswick, Canada (47°00 to 47°30 N, 67°20 to 68°10 W). The District is 190,000 ha and represents some of the most intensively managed forests in Canada. Sample plots were a subset of plots established as part of a harvesting trial. Plots were established on a systematic grid across the study area, and a subset was selected for this study to represent a range of stand conditions, densities, species compositions, and management regimes. Sampled plot characteristics are summarized in Table 1. Plot Establishment Tree Mapping Sample plots were established as variable-radius plots using a 1-m ha 1 basel area factor (BAF) angle gauge (1 m ha 1 4.356 ft ac ). The distance from plot center to each tallied tree (nearest 0.1 m) and the azimuth (nearest degree) were measured using a tape measure and compass mounted on a tripod and recorded in a field data collector. Distances were measured from plot center to the face of the tree. The dbh (to the nearest 0.01 m) of tallied trees was measured using tree calipers. Using recorded distance and tree diameter, the field data collector computed whether measured trees were in or out of the tally. This capability was useful in the field for assessing trees that were borderline based on the angle gauge. The tally sweep began at north azimuth (0°) and continued clockwise around the plot. Photo Measurements We evaluated tree distance measurements on photos using two methods: a) targets placed on trees; and b) tree dbh measured from the photograph. After measuring all trees, a target printed on card stock 21.6 27.9 cm was placed on each tree at breast height (1.3 m). In the center of each target was a 17.8 17.8-cm black square, and printed above this was an indexing tree number to relate photographic measurements to field measurements. The targets are not required to make the measurements and can be considered optional; however, it is important to have a method for indexing trees in the photos to tallied attributes. A digital camera mounted in portrait orientation on a panoramic tripod mount (Kaidan Kiwi) was placed on a tripod 1.3 m directly above the plot center. The panoramic tripod mount ensured that the camera’s focal point was directly above the rotational axis of the tripod, such that the resulting series of photographs could be stitched together with minimum distortion. The degree index on the mount was used to determine accurate camera rotation between photographs. Two camera models were used, an Olympus D550z (3 megapixels) and a Canon PowerShot SD200 (3.2 megapixels). Both cameras are entry-level “point-and-shoot” type cameras with a replacement cost between $150 and $200 each. The first plot photograph was taken oriented toward the first tree measured, and a series of 24 photographs, taken at 15° intervals around plot center, was then obtained. The 15° interval provided sufficient overlap between adjacent photographs to minimize distortion in the stitched panoramic image. Camera setup and photography averaged approximately 5 minutes per plot. Postprocessing Photographs were downloaded from the camera to a computer and organized into folders by plot. A software program called The Panorama Factory (Smoky City Design, LLC) was used to stitch Tree 1 x = 491.46p 7-degrees Tree 8 x = 2498.14p X-degrees Target measurement

Abstract: This invention provides an angle gauge that, when used in conjunction with a caliper or other linear measuring device, improves both the precision and ease with which angles can be measured and set by allowing the user accurately to measure and set angles in fractions of degrees. Using the gauge, an angle formed by the gauge may be determined or set by reference to the linear distance measured by the caliper. Calculations or tables can be used to convert the linear measurements into the angle setting or measurement with great accuracy, or the capacity to calculate the angle corresponding to the linear measurement can be built (i.e. programmed) directly into the device.

Abstract: An angle measurement and distance demarcation device has a body having a first surface, an axis which extends from the first surface, and a containing room. The device also has a rotating unit coupled for rotation about the axis, and a laser emitter. The device further includes a coupling mechanism provided around the axis and coupling the rotating unit to the body, and a power supply unit provided inside the containing room and coupled to the laser emitter for supplying power to laser emitter. The device can be used together with either a triangular angle gauge or a disk angle gauge.

Abstract: A novel, precise angle gauge is proposed. Incoming laser light is fed to the system through two separate condensing lenses. The phase difference between two rays is compensated by a phase modulator to hold a constant interference condition. The angle of the incoming light is measured by the modulation voltage. In comparison with conventional angle gauges, its advantages are high measurement accuracy, simple structure, and compatibility to feedback control systems. Because of these advantages, the angle gauge is suitable for navigation using angular information. Some examples of possible applications are provided. The experimental system was formed to be compatible with practical conditions and performance were verified experimentally. It is shown that an angle resolution less than 1*10/sup -7/ rd can be expected. >