The orientation of imagery relative to a compass bearing may be determined based on the position of the sun or other information relating to celestial bodies captured in the image.

The invention provides a surveying instrument, comprising a frame unit rotatable in a horizontal direction, a telescope unit as mounted rotatably in a vertical direction on the frame unit and further for sighting an object to be measured, a horizontal driving unit for rotating and driving the frame unit in a horizontal direction, a vertical driving unit for rotating the telescope unit in a vertical direction, a horizontal angle measuring unit for detecting a horizontal angle of the frame unit, a vertical angle measuring unit for detecting a vertical angle of the telescope unit and a control device, wherein the control device is adapted to calculate a solar altitude at a time moment by setting up coordinates of where the surveying instrument is installed and the time moment, and to make the telescope unit to set to the solar altitude as calculated by controlling the vertical driving unit, to control the horizontal driving unit, to execute searching of the sun by horizontally rotating the frame unit at the solar altitude as set up, to capture the sun, to sight the sun, to detect a horizontal angle under the sighted condition based on the horizontal angle measuring unit, and to survey a true north based on the horizontal angle as detected.

The invention provides a surveying instrument, comprising a frame unit rotatable in a horizontal direction, a telescope unit as mounted rotatably in a vertical direction on the frame unit and further for sighting an object to be measured, a horizontal driving unit for rotating and driving the frame unit in a horizontal direction, a vertical driving unit for rotating the telescope unit in a vertical direction, a horizontal angle measuring unit for detecting a horizontal angle of the frame unit, a vertical angle measuring unit for detecting a vertical angle of the telescope unit and a control device, wherein the control device is adapted to calculate a solar altitude at a time moment by setting up coordinates of where the surveying instrument is installed and the time moment, and to make the telescope unit to set to the solar altitude as calculated by controlling the vertical driving unit, to control the horizontal driving unit, to execute searching of the sun by horizontally rotating the frame unit at the solar altitude as set up, to capture the sun, to sight the sun, to detect a horizontal angle under the sighted condition based on the horizontal angle measuring unit, and to survey a true north based on the horizontal angle as detected.

An apparatus and system for use in determining location of a celestial body are presented. The apparatus comprises: a polarizer comprising an array of polarized light filter cells and a light sensor array. The array of polarized light filter cells comprises at least a first polarization direction and a second polarization direction different from said first polarization direction. And the polarizer thereby produces polarized light of at least first and second different polarizations. The light sensor array is configured to receive the polarized light from the polarizer and produce data indicative of a pattern of at least one of light polarization intensity and direction. The pattern is indicative of at least one of azimuth and elevation of the celestial body to be located.

An apparatus and system for use in determining location of a celestial body are presented. The apparatus comprises: a polarizer comprising an array of polarized light filter cells and a light sensor array. The array of polarized light filter cells comprises at least a first polarization direction and a second polarization direction different from said first polarization direction. And the polarizer thereby produces polarized light of at least first and second different polarizations. The light sensor array is configured to receive the polarized light from the polarizer and produce data indicative of a pattern of at least one of light polarization intensity and direction. The pattern is indicative of at least one of azimuth and elevation of the celestial body to be located.

A method for orienting includes: setting a digital optical imaging device including a photosensitive device, a lens, and a global navigation satellite system (GNSS) receiver; allowing an optical axis of the lens to pass through a geometric center of the photosensitive device, so that a celestial body is imaged on the photosensitive device; and positioning a current position by using the GNSS receiver, and recording an accurate time; calculating an accurate azimuth angle of the celestial body at this moment, wherein, at this time, an imaging position of the celestial body on the photosensitive device is located on an extension line of a ligature of the azimuth of the celestial body and a geometric center of the photosensitive device, thereby through accurately extracting the imaging position of the celestial body, a placement orientation of the digital optical imaging device is determined, and a north direction is obtained.

A method for orienting includes: setting a digital optical imaging device including a photosensitive device, a lens, and a global navigation satellite system (GNSS) receiver; allowing an optical axis of the lens to pass through a geometric center of the photosensitive device, so that a celestial body is imaged on the photosensitive device; and positioning a current position by using the GNSS receiver, and recording an accurate time; calculating an accurate azimuth angle of the celestial body at this moment, wherein, at this time, an imaging position of the celestial body on the photosensitive device is located on an extension line of a ligature of the azimuth of the celestial body and a geometric center of the photosensitive device, thereby through accurately extracting the imaging position of the celestial body, a placement orientation of the digital optical imaging device is determined, and a north direction is obtained.