Coded-light dual-view profile scanning apparatus
First Claim
1. A scan head for use in a scanner for projecting light onto an object to be scanned, and for detecting light reflected from the object;
- the scan head having precisely two spaced light projectors and two spaced light detectors;
wherein the projectors, when operating, operate in time-division multiplexed mode, and the detectors, when operating, each operate in synchrony to receive light reflected from both projectors.
0 Assignments
0 Petitions
Accused Products
Abstract
A scan head for a surface profile scanner includes two spaced laser projectors and two spaced CCD cameras, aligned with one another, for scanning an object such as a log or board moving along a sawmill production line and for determining the location of points on the surface of the scanned object, thereby generating data from which the surface profile of the object can be computed. For log scanning, the projectors both project coded light patterns. For board scanning, one projector projects a coded light pattern and the other a fan of uncoded light. The lasers and cameras are grouped in two pairs, one pair at each end of the scan head, preferably with the cameras bracketing the lasers, such that four sets of reflection data are available, through time-division multiplexing, in order to enable recognition of the image of the pattern reflected from the object and to optimize data readings from triangulation (to calculate the distances from the scan head to a series of points on the object). In the case of board scanning, the uncoded light image may be used for gray-scale image generation, board edge detection, and reflectivity compensation.
102 Citations
28 Claims
-
1. A scan head for use in a scanner for projecting light onto an object to be scanned, and for detecting light reflected from the object;
- the scan head having precisely two spaced light projectors and two spaced light detectors;
wherein the projectors, when operating, operate in time-division multiplexed mode, and the detectors, when operating, each operate in synchrony to receive light reflected from both projectors. - View Dependent Claims (2)
- the scan head having precisely two spaced light projectors and two spaced light detectors;
-
3. An array of spaced coplanar scan heads for scanning respective portions of a target object, each said scan head having precisely two spaced light projectors and two spaced light detectors;
- wherein, in operation
a. the projectors within each said scan head operate in time-division multiplexed mode;
b. the detectors within each said scan head operate in synchrony to receive light reflected from both projectors within such scan head; and
c. the scan heads operate in a timed sequence selected to avoid interference between neighboring scan heads. - View Dependent Claims (4)
- wherein, in operation
-
5. A scan head for use in a scanner for projecting light onto an object to be scanned, and for detecting light reflected from the object;
- the scan head having precisely two spaced projectors and two spaced detectors, wherein the detectors bracket the projectors.
- View Dependent Claims (6)
-
7. A scan head for use in a scanner for projecting light onto an object to be scanned, and for detecting light reflected from the object, the scan head having two spaced detectors and at least one projector for projecting coded light onto the object, wherein the projector is located proximate to one of the detectors and remote from the other, so that in operation, separate scan data are obtained from each said detector, the data respectively representing a near field of view and a far field of view.
-
8. A scan head for use in a scanner for projecting light onto a target object to be scanned, and for detecting light reflected from the object, the scan head having two spaced projectors and two spaced detectors;
- wherein in operation, one of the projectors projects a coded light pattern onto the object and the detectors receive and detect light reflected from the object that is correlatable with at least a distinguishable part of the projected pattern, and the other of the projectors projects a fan of light onto the object.
- View Dependent Claims (9)
-
10. Scanning apparatus for projecting coded light onto an object to be scanned, and for detecting light reflected from the object, comprising
a. a scan head having two spaced detectors and at least one projector for projecting coded light onto the object, wherein the projector is located proximate to one of the detectors and remote from the other, so that in operation, separate reflection data are obtained from each said detector, the data respectively representing a near field of view and a far field of view; - the detectors each providing an output representing the detected image at any time received by such detector; and
wherein the coded light comprises a pattern comprised of symbols each characterized by two or more distinguishable characteristics of the projected radiation;
b. symbol edge detection means for detecting in the output from the detectors beginning and end edges of the said symbol characteristics; and
c. matching means for matching portions of the detected image with portions of the projected pattern using at least some of the detected symbol edges. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
- the detectors each providing an output representing the detected image at any time received by such detector; and
-
20. Scanning apparatus for projecting light onto an object to be scanned, and for detecting light reflected from the object, comprising:
-
a. a scan head having two spaced detectors and at least one projector for projecting a coded light pattern onto the object, the detectors in operation each providing an output representative of the received reflected image at any time;
wherein the projector is located proximate to one of the detectors and remote from the other, and wherein in operation, separate reflection data are obtained from each said detector, the data respectively representing a near view and a far view;
b. pattern recognition means receiving the near-view data and correlating the received image data with the projected pattern to establish a match; and
c. far-view distance determination means receiving the far-view data for fine determination of the distance from a selected baseline of points on the scanned object illuminated by portions of the projected pattern that have been correlated with corresponding portions of the received image. - View Dependent Claims (21, 22, 23)
-
-
24. A method of processing reflection data obtained from scanning an object with a coded light pattern, comprising selection of data within one or more ranges established by the scanning layout and/or the angles of projection and view selected;
- and further processing only the selected data.
-
25. A method of processing reflection data obtained at two separate locations from the projection from a source onto a scanned object of a coded light pattern, comprising correlating the reflection data received at the location nearer the source with the projected pattern so as to establish a correlation between components of the reflected image of the projected pattern and points on the scanned object, approximating the distance from the said points on the scanned object to a selected baseline;
- and more precisely determining the distance from the said points on the scanned object to the selected baseline by triangulation computations on selected correlated data received at the location further from the source, including selecting for reliable triangulation computation only data for which the more precise distance determination is within the same selected distance range as the corresponding approximate distance determination.
-
26. A method of processing reflection data obtained from at least two separate light-detection locations from the reflection of an image from a scanned object of a coded light pattern projected onto the scanned object from a source of light, comprising triangulation computation of distance to an identified point on the scanned object from at least two discrete baselines, one said baseline being of a length correlatable with the distance from the source to one of the two separate locations, and the other said baseline being of a length correlatable with the distance from the source to the other of the two separate locations.
-
27. A method of processing reflection data obtained from two separate light-detection locations from the reflection of an image from a scanned object of a coded light pattern projected onto the scanned object from a source of light, comprising establishing the identity of scanned points from which the reflection data have been obtained at the two separate light-detection locations, and performing triangulation computation of distance to such identified points on the scanned object using as a baseline the line between the applicable detection focal points at the two separate light-detection locations.
-
28. A method of processing first and second sets of reflection data correlated with a selected range of pixel addresses with which the reflection data are associated, the first set of said reflection having been obtained from the reflection of at least a portion of a series of mark/space symbols projected onto a target object and being representative of the intensity of light reflected at each pixel address in the range, the marks being characterized by two or more duty-cycle values for purposes of mark recognition and identification, and the second set of data having been obtained as reflectivity data representative of the surface reflectivity of the scanned surface of the target object at each pixel address in the range, comprising compensating the first set of data using the second set of data thereby to obtain compensated data for the range of pixel addresses that reduces or mitigates the duty-cycle distortion of mark-related data induced by surface anomalies on the target object surface.
Specification