Method and arrangement in a measuring system

• US 8,923,599 B2
• Filed: 02/10/2004
• Issued: 12/30/2014
• Est. Priority Date: 10/02/2001
• Status: Active Grant

• Current Assignee: Sick IVP AB (Sick)
• Original Assignee: Sick IVP AB (Sick)
• Inventors: strm, Anders, strand, Erik
• Primary Examiner(s): TSAI, TSUNG YIN
• Application Number:
  US10/774,948
• Publication Number:
  US 20040234118A1
• Time in Patent Office: 3,976 Days
• Field of Search: 382/141, 382/298, 382/301, 375/240.12, 708/709, 712/32
• US Class Current: 382/141
• 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: G01B 11/303 using photoelectric detection means
• CPC Class Codes: G01N 21/8986 Wood
• CPC Class Codes: G01N 33/46 Wood

Abstract

The present invention relates to a method and an arrangement for representing the characteristics of an object with a measuring system, in which either the measuring system or the object is designed to move in relation to one another in a predefined direction of movement. The object preferably is designed to move in relation to the measuring system. At least one light source is designed to illuminate the object with a light which is incident upon the object and has a limited extension in the direction of movement. An imaging sensor, which is arranged on the same side of the object as the light source is designed to pick up light reflected from the object and to convert this into electrical charges. An image-processing unit is furthermore designed to create a digital representation of the object from said electrical charges. The light source is arranged at a predetermined distance from the imaging sensor viewed in the direction of movement, and the image-processing unit is designed to simultaneously read out information on the geometric profile of the object and information on the light scatter in a predetermined area around said profile.

Claims

1. A method for determining imaging characteristics of an object, the method comprising:

casting incident light in a linear shape from one light source onto a specific location on an object;

capturing detected light with one image sensor while casting the incident light, the detected light including at least (i) light from reflection of the incident light, and (ii) light from scattering of the incident light;

generating a record associated with the specific location from the detected light, the record including at least (i) first information about the reflection of the incident light, and (ii) second information about the scattering of the incident light; and

determining an object profile for the specific location and an object scattering property for the specific location by reading the first and second information in the record associated with the specific location.

2. The method of claim 1, wherein generating the record comprises forming a first image from the captured light.

3. The method of claim 2,

Wherein the light source is a laser forming a line of laser light on the object;

the first image contains a profile corresponding to the line of laser light on the object;

the object profile is determined using the profile in the first image; and

the object scattering property is determined using an intensity distribution of the profile in the first image.

4. The method of claim 3, wherein determining the object scattering property comprises:

identifying a middle area and an edge area in the intensity distribution; and

comparing an intensity in the edge area with at least an intensity in the middle area.

5. The method of claim 2, wherein generating the record further comprises processing the first image to generate a second image having a reduced data quantity compared to the first image.

6. The method of claim 5, wherein the first image includes image information distributed in rows and columns that represents at least part of the linear shape, and wherein the method further comprises:

(i) successively selecting respective subsets of the rows;

(ii) for each row in each of the subsets, determining whether the row'"'"'s portion of the image information meets a criterion, and if so registering in the record any of the columns where the criterion is exceeded; and

(iii) generating a representative row for each of the subsets using the image information of the rows in the respective subset, the second image formed by the representative rows and containing a version of the linear shape of the incident light.

7. The method of claim 6, wherein generating each representative row comprises:

processing the portion of the image information of each row in the subset; and

detecting, while processing, whether a sum of added image information for any of the columns exceeds the criterion.

8. The method of claim 7, wherein the processing comprises summing the portion of the image information of each row in the subset.

9. The method of claim 7, wherein the processing comprises performing a max operation on the portion of the image information of each row in the subset.

10. The method of claim 1, wherein the object is elongate in one direction essentially perpendicular to the linear shape of the incident light.

11. The method of claim 1, wherein at least one of the light source and the object is moving while the incident light is cast and the detected light is captured.

12. A system comprising:

one light source casting incident light in a linear shape onto a specific location on an object;

one image sensor capturing detected light while the incident light is being cast, the detected light including at least (i) light from reflection of the incident light, and (ii) light from scattering of the incident light; and

an image-processing unit generating a record associated with the specific location from the detected light, the record including at least (i) first information about the reflection of the incident light, and (ii) second information about the scattering of the incident light;

wherein the image-processing unit determines an object profile for the specific location and an object scattering property for the specific location by reading the first and second information in the record associated with the specific location.

13. The system of claim 12, wherein the record comprises a first image formed from the captured light.

14. The system of claim 13, wherein:

the light source is a laser forming a line of laser light on the object;

the first image contains a profile corresponding to the line of laser light on the object;

the object profile is determined using the profile in the first image; and

the object scattering property is determined using an intensity distribution of the profile in the first image.

15. The system of claim 13, wherein the image-processing unit determines the object scattering property by:

identifying a middle area and an edge area in the intensity distribution; and

comparing an intensity in the edge area with at least an intensity in the middle area.

16. The system of claim 13, wherein the image-processing unit generates the record by processing the first image to generate a second image having a reduced data quantity compared to the first image.

17. The system of claim 16, wherein the first image includes image information distributed in rows and columns that represents at least part of the linear shape, and wherein the image-processing unit further:

(i) successively selects respective subsets of the rows;

(ii) for each row in each of the subsets, determines whether the row'"'"'s portion of the image information meets a criterion, and if so registers in the record any of the columns where the criterion is exceeded; and

(iii) generates a representative row for each of the subsets using the image information of the rows in the respective subset, the second image formed by the representative rows and containing a version of the linear shape of the incident light.

18. The system of claim 17, wherein in generating each representative row the image-processing unit:

processes the portion of the image information of each row in the subset; and

detects, while processing the portion of the image information of each row in the subset, whether a sum of added image information for any of the columns exceeds the criterion.

19. The system of claim 18, wherein the image-processing unit sums the portion of the image information of each row in the subset.

20. The system of claim 18, wherein the image-processing unit performs a max operation on the portion of the image information of each row in the subset.

21. The system of claim 12, wherein the object is elongate in one direction essentially perpendicular to the linear shape of the incident light.

22. The system of claim 12, wherein at least one of the light source and the object is moving while the light source casts the incident light and the image sensor captures the detected light.