Detection of a sheet of light based on second derivative
First Claim
1. A method for detecting a position of a sheet of light in an image, the method comprising:
- applying a second derivative filter to an intensity profile of a line of pixels included in an image of the sheet of light as projected onto an object to obtain a plurality of second derivative values associated with corresponding pixel positions;
determining an ingress pixel position associated with an ingress zero-crossing second derivative value, wherein the ingress pixel position is between a first pixel position with a first minimum intensity value of the intensity profile and a second pixel position with a first maximum intensity value of the intensity profile;
determining an egress pixel position associated with an egress zero-crossing second derivative value, wherein the egress pixel position is between a third pixel position with a second maximum intensity value of the intensity profile and a fourth pixel position with a second minimum intensity value of the intensity profile;
determining a midpoint pixel position between the ingress pixel position and the egress pixel position; and
outputting the midpoint pixel position as the position of the sheet of light.
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Abstract
A method for detecting a position of a sheet of light is described. A second derivative filter is applied to an intensity profile of a line of pixels. An ingress pixel position associated with an ingress zero-crossing second derivative value is determined. The ingress pixel position is between a first pixel position with a first minimum intensity value of the intensity profile and a second pixel position with a first maximum intensity value of the intensity profile. An egress pixel position associated with an egress zero-crossing second derivative value is determined. The egress pixel position is between a third pixel position with a second maximum intensity value of the intensity profile and a fourth pixel position with a second minimum intensity value of the intensity profile. A midpoint pixel position between the ingress pixel position and the egress pixel position is output as the position of the sheet of light.
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Citations
27 Claims
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1. A method for detecting a position of a sheet of light in an image, the method comprising:
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applying a second derivative filter to an intensity profile of a line of pixels included in an image of the sheet of light as projected onto an object to obtain a plurality of second derivative values associated with corresponding pixel positions; determining an ingress pixel position associated with an ingress zero-crossing second derivative value, wherein the ingress pixel position is between a first pixel position with a first minimum intensity value of the intensity profile and a second pixel position with a first maximum intensity value of the intensity profile; determining an egress pixel position associated with an egress zero-crossing second derivative value, wherein the egress pixel position is between a third pixel position with a second maximum intensity value of the intensity profile and a fourth pixel position with a second minimum intensity value of the intensity profile; determining a midpoint pixel position between the ingress pixel position and the egress pixel position; and outputting the midpoint pixel position as the position of the sheet of light. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A field-programmable gate array (FPGA) to detect a position of a sheet of light in an image, the FPGA comprising:
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a set of one or more processing units; and a non-transitory machine-readable storage medium containing code, which when executed by the set of one or more processing units, causes the FPGA to; apply a second derivative filter to an intensity profile of a line of pixels included in an image of the sheet of light as projected onto an object to obtain a plurality of second derivative values associated with corresponding pixel positions, determine an ingress pixel position associated with an ingress zero-crossing second derivative value, wherein the ingress pixel position is between a first pixel position with a first minimum intensity value of the intensity profile and a second pixel position with a first maximum intensity value of the intensity profile, determine an egress pixel position associated with an egress zero-crossing second derivative value, wherein the egress pixel position is between a third pixel position with a second maximum intensity value of the intensity profile and a fourth pixel position with a second minimum intensity value of the intensity profile, determine a midpoint pixel position between the ingress pixel position and the egress pixel position, and output the midpoint pixel position as the position of the sheet of light. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A non-transitory computer readable storage medium that provide instructions, which when executed by a processor of a proxy server, cause said processor to perform operations comprising:
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applying a second derivative filter to an intensity profile of a line of pixels included in an image of a sheet of light as projected onto an object to obtain a plurality of second derivative values associated with corresponding pixel positions; determining an ingress pixel position associated with an ingress zero-crossing second derivative value, wherein the ingress pixel position is between a first pixel position with a first minimum intensity value of the intensity profile and a second pixel position with a first maximum intensity value of the intensity profile; determining an egress pixel position associated with an egress zero-crossing second derivative value, wherein the egress pixel position is between a third pixel position with a second maximum intensity value of the intensity profile and a fourth pixel position with a second minimum intensity value of the intensity profile; determining a midpoint pixel position between the ingress pixel position and the egress pixel position; and outputting the midpoint pixel position as a position of the sheet of light. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27)
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Specification