METHOD AND SYSTEM FOR DISTANCE ESTIMATION USING PROJECTED SYMBOL SEQUENCES

• US 20120086803A1
• Filed: 10/11/2010
• Published: 04/12/2012
• Est. Priority Date: 10/11/2010
• Status: Abandoned Application

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Malzbender, Thomas G., Ordentlich, Erik, Reth, Ron M.
• Application Number:
  US12/901,995
• Publication Number:
  US 20120086803A1
• Time in Patent Office: Days
• US Class Current: 348/140
• CPC Class Codes: G01B 11/026 by measuring distance between sensor and object G01B11/0608 takes precedence
• CPC Class Codes: G01B 11/25 by projecting a pattern, e.g. one or more lines, moiré fringes on the object G01B11/255 takes precedence ; image analysis for depth or shape recovery G06T7/50
• CPC Class Codes: G06T 7/521 from laser ranging, e.g. using interferometry; from the projection of structured light

Abstract

Certain examples of the present invention are directed to an image-recording device. The image-recording device includes an imaging component that records an image of an environment, a projection component that projects, into the environment, an (n,d) reliable M*-sequence of symbols, and a distance component. The distance component identifies j consecutive symbols reflected back to the imaging component from a surface in the environment, where j≧n, detects and corrects a misidentified symbol within the j consecutive symbols based on the minimum distance t of the (n,d) reliable M*-sequence, determines a first position of the j consecutive symbols with respect to the image, determines a second position of the j consecutive symbols in the M*-sequence of symbols, and determines, from the first and second position, a distance t from the surface to the imaging component.

Claims

1. An image-recording device comprising:

an imaging component that records an image of an environment;

a projection component that projects, into the environment, an (n,d) reliable M*-sequence of symbols; and

a distance component that

identifies j consecutive symbols reflected back to the imaging component from a surface in the environment, where j≧

n

detects and corrects a misidentified symbol within the j consecutive symbols based on the minimum Hamming distance d of the (n,d) reliable M*-sequence,

determines a first position of the j consecutive symbols with respect to the image,

determines a second position of the j consecutive symbols in the M*-sequence of symbols, and

determines, from the first and second position, a distance t from the surface to the imaging component.

2. The image-recording device of claim 1

wherein the projection component projects the M*-sequence of symbols in a non-visible-light wavelength;

wherein the image-recording device records the image as a single two-dimensional array of pixels, each pixel associated with one or more visible-light intensities and a non-visible-light-wavelength intensity; and

wherein the distance component determines the first position by identifying the subsequence of j consecutive symbols in the image by using the non-visible-light-wavelength intensities associated with pixels of the image.

4. The image recording device of claim 1

wherein projection component projects the M*-sequence of symbols for imaging by the imaging component to produce a reflected-symbol image;

and

wherein the image-recording device records the image of the environment when the projection component is not projecting the M*-sequence of symbols; and

wherein the distance component determines a position of the subsequence of j consecutive symbols in the reflected-symbol image and determines the first position by identifying a position in the image of the environment corresponding to the position of the subsequence of j consecutive symbols in the second image.

5. The image-recording device of claim 1 wherein the projection component projects a two-dimensional array of symbols into the environment.

6. The image-recording device of claim 5 wherein the two-dimensional array of symbols projected by the projection component into the environment is aligned with the two-dimensional array of pixels produced in an imaging operation by the imaging component.

7. The image-recording device of claim 5 wherein each row of the two-dimensional array of symbols comprises one or more M*-sequences of symbols.

8. The image-recording device of claim 5 wherein each column of the two-dimensional array of symbols comprises one or more M*-sequences of symbols.

9. The image-recording device of claim 5 wherein the two-dimensional array of symbols comprises an M*-sequence of symbols, successive subsequences of which are selected or each row of the two-dimensional array of symbols.

10. The image-recording device of claim 5 wherein the two-dimensional array of symbols comprises an M*-sequence of symbols, successive subsequences of which are selected for each column of the two-dimensional array of symbols.

11. The mage-recording device of claim 1 wherein the distance component determines, from the first and second position, a distance t from the surface to the imaging component by:

determining, from a known geometry of, and relative positions of components within, the image-recording device, a base distance b along a base line from a first reference point associated with the projection component to a second reference point associated with the imaging component;

determining, from a known geometry of and relative positions of components within, the image-recording device and from the first and second position, a projection angle P between a line of symbol projection from the first reference point to the surface in the environment and the base line and a camera angle C between a line of symbol reflection from the surface in the environment to second reference point and the base line; and

determining a distance t from the surface to the image-recording device as

12. The image-recording device of claim 1 wherein the distance component detects and corrects a misidentified symbol within the j consecutive symbols based on the minimum distance d of the (n,d) reliable M*-sequence by:

determining, from a known geometry of, and relative positions of components within, the image-recording device, an M*-sequence projected by the projection component that includes symbols reflected back to the imaging component as the j consecutive symbols;

employing a syndrome decoder for a linear block code comprising codewords of length n corresponding to the M*-sequence to determine a most likely subsequence of n consecutive symbols within the M*-sequence corresponding to n consecutive symbols within the j consecutive symbols.

13. The image-recording device of claim 1 wherein the distance component detects and corrects a misidentified symbol within the j consecutive symbols based on the minimum distance d of the (n,d) reliable M*-sequence by:

determining from a known geometry of, and relative positions of components within, the image-recording device, an M*-sequence projected by the projection component that includes symbols reflected back to the imaging component as the j consecutive symbols; and

determining, as a most likely subsequence of n consecutive symbols within the M*-sequence, a subsequence of n consecutive symbols within the M*-sequence closest in Hamming distance to a corresponding subsequence of n consecutive symbols within the j consecutive symbols.

14. The image-recording device of claim 1 wherein the distance component additionally records the distance t from the surface to the imaging component in an electronic memory or mass-storage device.

3. The image-recording device of claim

wherein the projection component projects the M*-sequence of symbols in a non-visible-light wavelength;

wherein the image-recording device records the image as two two-dimensional arrays of pixels, each pixel in the first two-dimensional array of pixels associated with one or more visible-light intensities and each pixel in the second two-dimensional array of pixels associated a non-visible-light-wavelength intensity; and

wherein the distance component determines a position of the subsequence of j consecutive symbols in the second image and determines the first position by identifying a position in the first image corresponding to the position of the subsequence of j consecutive symbols in the second image.

15. A method for determining a distance t to associate with a region of an image of an environment recorded by an image-recording device, the method comprising:

projecting, into the environment, an (n,d) reliable M*-sequence of symbols;

recording the image of the environment;

identifying j consecutive symbols reflected back to the imaging component from a surface in the environment, where j≧

n;

detecting and correcting a misidentified symbol within the j consecutive symbols based on the minimum distance d of the (n,d) reliable M*-sequence;

determining a first position of the j consecutive symbols with respect to the image;

determining a second position of the j consecutive symbols in the M*-sequence of symbols; and

determining, the first and second position, a distance t from the surface to the imaging component.

16. The method claim 15 wherein determining, from the first and second position, a distance t from the surface to the image-recording device further includes:

determining, from a known geometry of, and relative positions of components within, the image-recording device, a base distance b along a base line from a first reference point associated with a projection component to a second reference point associated with an imaging component;

determining, from the known geometry of, and relative positions of components within, the image-recording device and from the first and second position, a projection angle P between a line of symbol projection from the first reference point to the surface in the environment and the base line and a camera angle C between a line of symbol reflection from the surface in the environment to the second reference point, and the base line; and

determining a distance t from the surface to the image-recording device as

17. The method of claim 15 wherein detecting and correcting a misidentified symbol within the j consecutive symbols based on the minimum Hamming distance d of the (n,d) reliable M*-sequence further comprises:

determining, from a known geometry of, and relative positions of components within, the image-recording device, an M*-sequence projected by the projection component that includes symbols reflected back to the imaging component as the j consecutive symbols;

employing a syndrome decoder for a linear block code comprising codewords of length n corresponding to the M*-sequence to determine a most likely subsequence of n consecutive symbols within the M*-sequence corresponding to n consecutive symbols within the j consecutive symbols.

18. The method of claim 15 wherein detecting and correcting a misidentified symbol within the j consecutive symbols based on the minimum Hamming distance d of the (n,d) reliable M*-sequence further comprises:

determining, from a known geometry of, and relative positions of components within, the image-recording device, an M*-sequence projected by the projection component that includes symbols reflected back to the imaging component as the j consecutive symbols; and

determining, as a most likely subsequence of n consecutive symbols within the M*-sequence, a subsequence of n consecutive symbols within the M*-sequence closest in Hamming distance to a corresponding subsequence of n consecutive symbols within the j consecutive symbols.

19. A distance-measuring device comprising:

a projection component that projects, into an environment, an (n,d) reliable M*-sequence of symbols; and

a distance component that

identifies j consecutive symbols reflected back to the distance-measuring device from a surface in the environment, where j≧

n,

detects and corrects a misidentified symbol within the j consecutive symbols based on the minimum Hamming distance d of the (n,d) reliable M*-sequence,

determines a first position of the j consecutive symbols reflected back to the distance-measuring device relative to a first reference point,

determines a second position of the j consecutive symbols in the M*-sequence of symbols relative to a second reference point,

determines, from the first and second position, a distance t from the surface to the distance-measuring device, and

records the distance t from the surface to the distance-measuring device in an electronic memory or mass-storage device.

20. The distance-measuring device of claim 19 wherein the distance component determines, from the first and second position, as distance t from the surface to the imaging component by:

determining, from a known geometry of, and relative positions of components within, the distance-measuring device, a base distance b along a base line from the first reference point to the second reference point;

determining, from a known geometry of, and relative positions of components within, the distance-measuring device and from the first and second position, an angle P between a line of symbol projection from the first reference point to the surface in the environment and the base line and an angle C between a line of symbol reflection from the surface in the environment to the second reference point and the base line; and

determining a distance t from the surface to the distance-measuring device as