Photography – With exposure objective focusing means – focusing aid – or... – Having auxiliary illumination
Patent
1997-12-19
2000-07-18
Gray, David M.
Photography
With exposure objective focusing means, focusing aid, or...
Having auxiliary illumination
356 407, G03B 1724
Patent
active
060919051
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
The present invention relates to three-dimensional cameras and, more particularly, to systems for accurately determining the distance to various objects and portions of objects in the scene.
Various techniques are known for creating a three-dimensional image of a scene, i.e., a two-dimensional image which, in addition to indicating the lateral extent of objects in the scene, further indicates the relative or absolute distance of the objects, or portions thereof, from some reference point, such as the location of the camera.
At least three basic techniques are commonly used to create such images. In one technique, a laser or similar source of radiation is used to send a pulse to a particular point in the scene. The reflected pulse is detected and the time of flight of the pulse, divided by two, is used to estimate the distance of the point. To obtain the distance of various points in the scene, the source is made to scan the scene, sending a series of pulses to successive points of the scene.
In yet another technique, a phase shift, rather than time of flight, is measured and used to estimate distances. Here, too, the entire scene or relevant portions thereof must be scanned one point at a time.
In a third technique, which also involves scanning, at least a single radiation source and corresponding detector are used, with suitable optics which act on the light in a manner which depends on the distance to the object being examined, to determine the distance to a particular point in the scene using a triangulation technique.
The major disadvantage of all three of the above-described techniques is that each requires point by point or line by line scanning to determine the distance of the various objects in the scene. Such scanning significantly increases the frame time of the system, requires expensive scanning equipment and necessitates the use of fast and powerful computational means and complex programming.
There is thus a widely recognized need for, and it would be highly advantageous to have, a method and system for rapidly and easily determining the distance of various points in a scene without the need for scanning and complex computational capabilities.
SUMMARY OF THE INVENTION
According to the present invention there is provided a telecentric system for creating an image indicating distances to various objects in a scene, comprising: (a) a source of radiation for directing source radiation at the scene; (b) a detector for detecting the intensity of radiation reflected from the objects in the scene; (c) a source modulator for modulating the source of radiation; (d) means for collimating a portion of the radiation reflected from the objects in the scene; (e) a reflected radiation modulator for modulating the collimated radiation reflected from the objects in the scene, the reflected radiation modulator being selected from the group consisting of acousto-optical devices and electro-optical devices; (f) a source modulator control mechanism for controlling the source modulator; and (g) a reflected radiation modulator control mechanism for controlling the detector modulator.
According to a preferred embodiment of the present invention, the source modulator control mechanism and the detector modulator control mechanism operate to simultaneously control the source modulator and the detector modulator.
According to further features in preferred embodiments of the invention described below, the modulator of the source radiation and the modulator of the reflected radiation serve to alternately block and unblock or alternately activate and deactivate the source radiation and reflected radiation, respectively.
According to still further features in the described preferred embodiments the source of radiation is a source of visible light, such as a laser and the detector includes photographic film, or a video camera sensor, such as a Charge Coupled Device (CCD.)
According to yet further features, the method further includes processing the intensity of radiation reflected fro
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Iddan Gavriel
Yahav Giora
3DV Systems, Ltd
Gray David M.
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