A large-dip-angle self-leveling device is provided. The device comprises a mounting base platform arranged on a mounting stand column and a support cylinder connected with the mounting base platform. A leveling plate is arranged at the top of the mounting base platform, and a leveling platform is arranged on the leveling plate. A spirit bubble indicator and a control circuit board are arranged on the leveling platform. A connecting rod of balance weight is arranged in the support cylinder, one end of the connecting rod of balance weight is connected with the leveling platform, and the other end is connected with a balance weight. A four-core cable penetrates through the connecting rod of balance weight and the balance weight. Observation windows are symmetrically arranged at the lower part of the support cylinder. A melting pool is arranged at the bottom in the support cylinder.

A large-dip-angle self-leveling device is provided. The device comprises a mounting base platform arranged on a mounting stand column and a support cylinder connected with the mounting base platform. A leveling plate is arranged at the top of the mounting base platform, and a leveling platform is arranged on the leveling plate. A spirit bubble indicator and a control circuit board are arranged on the leveling platform. A connecting rod of balance weight is arranged in the support cylinder, one end of the connecting rod of balance weight is connected with the leveling platform, and the other end is connected with a balance weight. A four-core cable penetrates through the connecting rod of balance weight and the balance weight. Observation windows are symmetrically arranged at the lower part of the support cylinder. A melting pool is arranged at the bottom in the support cylinder.

Through its unique trapezoidal shape and strategically placed vials, the combination level and right angle measuring tool requires only one user to not only quickly verify if a long object is horizontal or vertical but also to easily determine if the angle of the intersection of two long objects is 90 degrees. To obtain the right angle measurement, the combination level and right angle measuring tool employs the 3-4-5 rule (an application of the Pythagorean Theorem, where a.sup.2+b.sup.2=c.sup.2) in its design, eliminating the need for lasers or movable parts.

Through its unique trapezoidal shape and strategically placed vials, the combination level and right angle measuring tool requires only one user to not only quickly verify if a long object is horizontal or vertical but also to easily determine if the angle of the intersection of two long objects is 90 degrees. To obtain the right angle measurement, the combination level and right angle measuring tool employs the 3-4-5 rule (an application of the Pythagorean Theorem, where a.sup.2+b.sup.2=c.sup.2) in its design, eliminating the need for lasers or movable parts.

A laser-level device has a body having a length, a height and a width, with a base, sides and a top, an upper slider engaging a longitudinal track along the top of the device, connected through a lengthwise channel to a lower slider element within the body, a laser module carrying a laser, engaged in a track curved in an arc of about ninety degrees, and a first link engaged pivotally to the lower slider element on a first end and pivotally to the laser module on a second end. The laser module follows the track curvature in response to translation of the slider along the longitudinal track from a fully retracted position to a fully extended position, and the laser emits a laser beam through the central, lengthwise channel, the beam moving in an arc determined by the track curvature.

A laser-level device has a body having a length, a height and a width, with a base, sides and a top, an upper slider engaging a longitudinal track along the top of the device, connected through a lengthwise channel to a lower slider element within the body, a laser module carrying a laser, engaged in a track curved in an arc of about ninety degrees, and a first link engaged pivotally to the lower slider element on a first end and pivotally to the laser module on a second end. The laser module follows the track curvature in response to translation of the slider along the longitudinal track from a fully retracted position to a fully extended position, and the laser emits a laser beam through the central, lengthwise channel, the beam moving in an arc determined by the track curvature.

A plumb-bob device has an enclosure with three lasers projecting from one end, one of which projects a horizontal lane, one in a vertical plane, and one with crossed planes from a laser that is suspended to swing but not rotate about an axis. The device may be attached to an object to be leveled or plumbed, and moving the object until the lasers coincide accomplishes plumbing the object.

A technique that enables easily determining an attitude of a laser scanning apparatus is provided. A surveying device includes a sunlight incident direction measurement unit, a Sun direction acquisition unit, and an attitude calculator. The sunlight incident direction measurement unit measures an incident direction of sunlight that enters a laser scanning apparatus, based on a detected waveform of incident light entering the laser scanning apparatus. The Sun direction acquisition unit acquires a direction of the Sun as seen from the laser scanning apparatus, from astronomical data, based on a position of the laser scanning apparatus. The attitude calculator calculates an attitude of the laser scanning apparatus in an absolute coordinate system, based on the incident direction of sunlight and the direction of the Sun as seen from the laser scanning apparatus, which is acquired from the astronomical data.

A technique that enables easily determining an attitude of a laser scanning apparatus is provided. A surveying device includes a sunlight incident direction measurement unit, a Sun direction acquisition unit, and an attitude calculator. The sunlight incident direction measurement unit measures an incident direction of sunlight that enters a laser scanning apparatus, based on a detected waveform of incident light entering the laser scanning apparatus. The Sun direction acquisition unit acquires a direction of the Sun as seen from the laser scanning apparatus, from astronomical data, based on a position of the laser scanning apparatus. The attitude calculator calculates an attitude of the laser scanning apparatus in an absolute coordinate system, based on the incident direction of sunlight and the direction of the Sun as seen from the laser scanning apparatus, which is acquired from the astronomical data.

Embodiments described herein are directed to an apparatus for determining a direction in which a tree will fall and a method for using the apparatus. The apparatus may comprise a plate including a substantially straight edge suitable for alignment with a vertex formed by a top cut and a bottom cut of a notch cut into a tree and a substantially level bottom surface suitable for stable placement upon the bottom cut of the notch. In some embodiments, the plate may define an internal cavity sized to accommodate a laser light generator. In other embodiments, a rotatable housing including a cavity sized to accommodate a laser light generator may be adjoined to the plate. Embodiments may permit a laser light generator contained within the cavity or the housing to emanate a beam of laser light in a direction that is substantially perpendicular to the substantially straight edge of the plate.