DETERMINING POSITIONAL INFORMATION FOR AN OBJECT IN SPACE
System and methods for locating objects within a region of interest involve, in various embodiments, scanning the region with light of temporally variable direction and detecting reflections of objects therein; positional information about the objects can then be inferred from the resulting reflections.
1 . A method for obtaining positional information about an object within a region of interest, the method comprising:
(a) activating sources directed to portions of the region of interest according to an ordering of points, such that each point in the ordering directs electromagnetic radiation of at least one source to one of the portions of the region of interest;
(b) capturing a portion of the electromagnetic radiation reflected by an object;
(c) forming a signal over time of at least one property of the captured electromagnetic radiation;
(d) determining from the signal, at least one point in the ordering in which a dominant contributor to the captured electromagnetic radiation was activated;
(e) determining an identity for the dominant contributor from the point in the ordering;
(f) determining from the identity of the dominant contributor, a portion of the region of interest to which the electromagnetic radiation from the dominant contributor was directed; and
(g) determining positional information for the object based at least in part upon the portion of the region of interest.
2 . The method of claim 1 , wherein capturing electromagnetic radiation reflected by the object comprises capturing data frames of the region with a pixelated sensor.
3 . The method of claim 2 , further comprising determining a direction of the reflected electromagnetic radiation relative to the sensor, the positional information further being based in part on the direction of the reflected electromagnetic radiation.
4 . The method of claim 2 , wherein the data frames are captured at a rate exceeding a scan rate associated with the illuminating electromagnetic radiation.
5 . The method of claim 2 , wherein determining a direction of the illuminating electromagnetic radiation associated with the electromagnetic radiation reflected by the object comprises determining an intensity peak across a temporal sequence of data frames for at least one pixel corresponding to the object within the data frame.
6 . The method of claim 5 , wherein determining the intensity peak comprises performing a Fourier transform on the temporal sequence of data frames for the at least one pixel.
7 . The method of claim 1 , wherein the electromagnetic radiation is retro-reflected by the object.
8 . The method of claim 7 , further comprising physically associating the object with a retro-reflector.
9 . The method of claim 1 , wherein the region is scanned periodically.
10 . The method of claim 1 , wherein the point in the ordering corresponding to capture of the reflected electromagnetic radiation corresponds to a phase within an emission cycle.
11 . The method of claim 10 , wherein determining the direction of the illuminating electromagnetic radiation associated with the electromagnetic radiation reflected by the object comprises determining the point in the cycle where the captured radiation is greatest.
12 . The method of claim 11 , wherein the point in the cycle is detected using a phase-detector circuit.
13 . The method of claim 1 , wherein scanning the region comprises sequentially operating a plurality of light-emitting devices emitting light to respective different portions of the region of interest.
14 . The method of claim 13 , further comprising operating only a subset of the plurality of light-emitting devices so as to reduce a resolution of the scan.
15 . The method of claim 13 , wherein sequentially operating the plurality of devices comprises sequentially causing the devices to emit pulses of light.
16 . The method of claim 15 , wherein successive pulses overlap temporally.
17 . The method of claim 13 , wherein sequentially operating the plurality of devices comprises driving each device according to a time-variable intensity having an intensity peak, the peaks occurring sequentially for the plurality of light-emitting devices.
18 . The method of claim 18 , wherein light emitted by the plurality of light-emitting devices overlap spatially and temporally, determining a direction of the illuminating light associated with the light reflected by the object comprising determining an effective primary direction of the overlapping illuminating light.
19 . The method of claim 1 , wherein scanning the region comprises moving a light-emitting device.
20 . The method of claim 1 , wherein scanning the region comprises moving at least one of a deflecting optic or a screen used in conjunction with a light-emitting device.
21 . The method of claim 1 , wherein the positional information comprises at least one of a distance, a depth, or a position of at least one of the object or a surface feature thereof.
22 . The method of claim 1 , wherein the positional information comprises a depth profile of the object.
23 . The method of claim 1 , wherein the positional information is determined further based at least in part on a geometric relationship between the source and the detector.
24 . The method of claim 1 , further comprising periodically repeating steps (a) through (c) so as to update the positional information to track movement of the object.
25 . A system for obtaining positional information about an object within a region of interest, the system comprising:
a directed light source with variable direction for scanning the region with an illuminating light;
a detector for capturing light reflected by the object, and
circuitry for (i) determining a time of capture of the reflected light and, based thereon, an associated direction of the illuminating light, and (ii) deriving the positional information about the object at least in part from the direction of the illuminating light.
26 . The system of claim 25 , wherein the directed light source comprises a plurality of light-emitting devices emitting light in a respective plurality of different primary directions.
27 . The system of claim 26 , wherein the directed light source further comprises a controller for sequentially operating the plurality of light-emitting devices.
28 . The system of claim 26 , wherein the light-emitting devices comprise light-emitting diodes.
29 . The system of claim 26 , wherein the light-emitting devices are arranged such that their respective primary directions intersect at a common center.
30 . The system of claim 29 , wherein the light-emitting devices are affixed to at least one of an arcuate surface, facets of a polygonal surface, or facets of a polyhedral surface.
31 . The system of claim 28 , wherein the plurality of light-emitting devices comprises a plurality of light emitters and a plurality of associated deflecting optics for deflecting light emitted by the emitters into the different primary directions.
32 . The system of claim 27 , wherein the directed light source comprises at least one moving light-emitting devices.
33 . The system of claim 27 , wherein the directed light source comprises at least one light-emitting device and at least one of a moving deflecting optic or a moving screen having a perforation therein.
34 . The system of claim 27 , wherein the detector comprises a camera for imaging the region.
35 . The system of claim 34 , wherein the camera comprises a lens and a sensor.
36 . The system of claim 35 , wherein the sensor comprises at least one of a CCD sensor or a MEMS sensor.
37 . The system of claim 34 , wherein the camera comprising a light-sensing device and a scanning mirror.
38 . The system of claim 25 , wherein the detector is co-located with the light source, the system further comprising a retro-reflector affixed to the object.
39 . The system of claim 25 , wherein the directed light source comprises a controller for varying the emission direction so as to periodically scan the region.
40 . The system of claim 39 , wherein the controller is synchronized with the circuitry.
41 . The system of claim 39 , wherein the circuitry causes the detector to be read out at a rate exceeding the scan rate of the directed light source.
42 . The system of claim 39 , wherein the circuitry comprises a phase-detector circuit for determining a phase within an emission cycle corresponding to a maximum intensity of the captured light.
43 . The system of claim 39 , wherein the circuitry comprises a digital processor configured for performing a Fourier transform on the captured light to thereby determine a phase within an emission cycle corresponding to a maximum intensity of the captured light.
44 . The system of claim 25 , further comprising a retro-reflector affixed to the object.
45 . A method for determining depth associated with at least one object within a region of interest, the method comprising:
scanning the region with an illuminating light beam having a temporally variable beam direction so as to illuminate the at least one object;
acquiring a temporal sequence of images of the region while the region is being scanned, each image corresponding to an instantaneous direction of the illuminating light beam, at least one of the images capturing light reflected by the at least one illuminated object; and
based at least in part on the instantaneous direction of the light beam in the at least one image capturing light reflected by the at least one object, determining a depth associated with the at least one object.
46 . The method of claim 46 , wherein multiple of the images acquired during a single scan of the region capture light reflected by the at least one object, the method comprising determining a depth profile of the at least one object based thereon.
47 . A method for locating an object within a region, the method comprising:
using a light source affixed to the object, scanning the region with an illuminating light beam having a temporally variable beam direction;
using a sensor co-located with the light source, capturing reflections of the illuminating beam from a plurality of retro-reflectors fixedly positioned at known locations;
based on times of capture of the reflections, determining associated directions of the illuminating light beam; and
locating the object relative to the known locations of the retro-reflectors based at least in part on the directions of the illuminating light beam.
48 . The method of claim 48 , wherein the object is located in a two-dimensional region based on reflections from at least three retro-reflectors.
49 . A device, affixed to an object of interest, for locating the object within a region relative to a plurality of retro-reflectors fixedly positioned at known locations, the device comprising:
a light source for scanning the region with an illuminating light beam having a temporally variable beam direction;
a sensor co-located with the light source for capturing reflections of the illuminating beam from the plurality of retro-reflectors;
circuitry for determining, from times of capture of the reflections, directions of the illuminating light beam associated therewith, and for locating the object relative to the retro-reflectors based at least in part on the directions.
50 . The device of claim 50 , wherein the object is a mobile device.
51 . A computer-implemented method for conducting machine control, the method comprising:
scanning a region of space, the scanning including (i) directing at least one light emission from a vantage point of a vantage region to a region of space, (ii) detecting a reflectance of the at least one light emission, and (iii) determining that the detected reflectance indicates a presence of an object in the region of space;
determining one or more object attributes of the object;
analyzing the one or more object attributes to determine a potential control surface of the object;
determining that control-surface attribute changes in the potential control surface indicate control information; and
responding to the indicated control information according to response criteria.
52 . A computer-implemented method according to claim 52 , wherein the first light emission is directed to the region of space according to a first scan pattern, and wherein determining that the detected reflectance indicates a presence of an object comprises directing a second light emission to the region of space according to a second scan pattern.
53 . A computer-implemented method according to claim 53 , wherein directing the second emission comprises:
scanning to a refined scan pattern.
54 . A computer-implemented method according to claim 54 , wherein scanning to the refined scan pattern includes capturing surface detail about the object.
55 . A computer-implemented method according to claim 52 , wherein determining object attributes of the object comprises:
determining positional information of at least a portion of the object.
56 . A computer-implemented method according to claim 56 , wherein analyzing the object attributes to determine a potential control surface of the object comprises:
determining based at least in part upon the positional information whether a portion of the object provides control information.
57 . A computer-implemented method according to claim 57 , wherein determining whether one or more control-surface attribute changes in the potential control surface indicate control information comprises:
determining whether control-surface attribute changes in the potential control surface indicate an engagement gesture.
58 . A computer-implemented method according to claim 58 , wherein responding to the indicated control information according to response criteria comprises:
determining a command to a user interface based at least in part upon the engagement gesture.
59 . A computer-implemented method according to claim 52 , wherein determining object attributes of the object comprises:
determining dynamic information of at least a portion of the object.
60 . A computer-implemented method according to claim 52 , wherein determining object attributes of the object comprises:
determining physical information of at least a portion of the object.
61 . A computer-implemented method according to claim 52 , wherein determining object attributes of the object comprises:
determining at least one of optical or radio properties of at least a portion of the object.
62 . A computer-implemented method according to claim 52 , wherein determining object attributes of the object comprises:
determining chemical properties of at least a portion of the object.
63 . A computer-implemented method according to claim 1 , wherein:
directing the emission includes scanning across an entryway;
determining that the detected reflectance indicates a presence includes detecting an object comprising a person seeking entrance, and conducting a second scanning to a refined scan pattern of the person;
determining whether control-surface attribute changes in the potential control surface indicate control information includes determining whether the control-surface attribute changes indicate a vein pattern of a hand of the person; and
responding to the indicated control information according to response criteria comprises permitting the person to enter when the vein pattern matches a stored vein pattern of an individual authorized to enter.