DIGITAL SOLAR COMPASS
First Claim
Patent Images
1. A digital solar compass, comprising:
- a planar image sensor for capturing an image;
a gnomon extending perpendicular to the plane of the image sensor; and
a signal processor arranged to determine the angle of a shadow cast by the sun and the gnomon from the image captured by the planar image sensor.
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Abstract
A digital solar compass has a planar image sensor (5) for capturing an image of a gnomon (1) perpendicular to the plane of the image sensor. A cover (12) protects the gnomon and image sensor. A signal processor (14) is arranged to determine the angle of a shadow cast by the sun and the gnomon from the image captured by the planar image sensor. The gnomon (1) may be mounted directly on the planar image sensor (5) or the shadow may be formed on a diffuser sheet (3) and projected onto the image sensor (5) using a lens (4).
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Citations
19 Claims
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1. A digital solar compass, comprising:
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a planar image sensor for capturing an image; a gnomon extending perpendicular to the plane of the image sensor; and a signal processor arranged to determine the angle of a shadow cast by the sun and the gnomon from the image captured by the planar image sensor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method of determining the angle of the sun with respect to a digital solar compass having a planar image sensor and a gnomon extending perpendicular to the plane of the image sensor;
- the method comprising;
forming a shadow of the gnomon on the image sensor; capturing the image on the image centre; calculating the locus of a circle around the centre of the image of the base of the gnomon; determining the intensity around the loop; and determining the angle of the shadow from the intensity around the loop. - View Dependent Claims (14, 15, 16)
- the method comprising;
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17. A method of determining the angle of the sun with respect to a digital solar compass having a planar image sensor and a gnomon extending perpendicular to the plane of the image sensor;
- the method comprising;
forming a shadow of the gnomon on the image sensor; capturing the image on the image centre; detecting the location of a plurality of points along the edge of the shadow; fitting a straight line using a fit to the location of the plurality points, and calculating the angle of the shadow from the fit. - View Dependent Claims (18, 19)
- the method comprising;
Specification