FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates to dental measurements, and more particularly, but not exclusively, to optical patterns for intra-oral scanning.

U.S. Pat. No. 7,724,932 B2 to Maurice et al. discloses “A method for creating three-dimensional models of intra-oral scenes and features. The intra-oral scene is illuminated by a two-dimensional array of structured illumination points, with anti-aliasing achieved by using stored two-dimensional patterns of pixels for anti-aliasing. Using a single camera to form images reduces the amount of apparatus necessary to introduce into the patient's mouth. Three-dimensional models are obtained from the single image by triangulation with a stored image of the structured illumination onto a reference surface such as a plane. Alternative methods include the use of “bar-coded” one-dimensional patterns.” (Abstract)

Rapid shape acquisition using color structured light and multi-pass dynamic programming” L Zhang, B Carless, S M Seitz—3D Data Processing, 2002, appears to present, “a color structured light technique for recovering object shape from one or more images. The technique works by projecting a pattern of stripes of alternating colors and matching the projected color transitions with observed edges in the image. The correspondence problem is solved using a novel, multi-pass dynamic programming algorithm that eliminates global smoothness assumptions and strict ordering constraints present in previous formulations. The resulting approach is suitable for generating both high-speed scans of moving objects when projecting a single stripe pattern and high-resolution scans of static scenes using a short sequence of time-shifted stripe patterns. In the latter case, space-time analysis is used at each sensor pixel to obtain inter-frame depth localization. Results are demonstrated for a variety of complex scenes.”

U.S. Pat. No. 9,593,982 apparently discloses, “A smartphone,” “adapted for use as an imaging spectrometer, by synchronized pulsing of different LED light sources as different image frames are captured by the phone's CMOS image sensor. A particular implementation employs the CIE color matching functions, and/or their orthogonally transformed functions, to enable direct chromaticity capture. A great variety of other features and arrangements are also detailed.”

All of which are incorporated herein by reference

SUMMARY OF THE INVENTION

According to an aspect of some embodiments of the invention, there is provided a method for structured light scanning of an intra-oral scene, comprising projecting onto the intra-oral scene a color-coded pattern comprising an arrangement of entities having edges between them; each entity comprising a different narrow band of wavelengths; and detecting the projected pattern as a plurality of pixels in an acquired image of the scene using at least two narrowband filters, wherein for each pixel of at least 95% of the pixels of an entity of interest comprising a first band of wavelengths, a contribution of light from a second band of wavelengths of an adjacent entity is less than 10%.

According to an aspect of some embodiments of the invention, there is provided a method for structured light scanning of an intra-oral scene, including projecting onto the intra-oral scene a color-coded pattern including an arrangement of entities having edges between them; each entity including a different wavelength bands; detecting the projected pattern as a plurality of pixels in an acquired image of the scene, and differentiating between the different wavelength bands in the image by separating between at least two spectral bands wherein at least one of the spectral bands a narrow band; restoring the projected pattern by associating an imaged entity to a projected entity by identifying the wavelength band of the projected entity in the image.

According to some embodiments of the invention, the differentiated is performed using at least two narrowband filters.

According to some embodiments of the invention, at least one of the at least two narrowband filters captures least 95% of the pixels of the at least one spectral band.

According to some embodiments of the invention, the differentiating is into at least 5 wavelength bands.

According to some embodiments of the invention, at least one of the filters includes an interference filter.

According to some embodiments of the invention, the pattern entities includes parallel stripes.

According to some embodiments of the invention, the pattern includes at least 8 different wavelength bands.

According to some embodiments of the invention, the at least wavelength bands are selected from the range of 400-500 nm.

According to some embodiments of the invention, the differentiating is effective to reduce spatial crosstalk between the pattern entities, caused as a result of volume scattering of the projected light inside contents of the intra-oral scene.

According to some embodiments of the invention, the different wavelengths are projected and/or detected simultaneously.

According to some embodiments of the invention, the different wavelengths are projected and/or detected sequentially in time.

According to an aspect of some embodiments of the invention, there is provided a scanner system for imaging an intra-oral scene including: an intraoral portion sized and shaped for insertion into the oral cavity, the intraoral portion including: a light source configured for projecting a color-coded pattern onto the intra-oral scene; a spectral imager positioned to image the scene.

According to some embodiments of the invention, the pattern includes lines in at least one direction.

According to some embodiments of the invention, the imager includes an array of pixels arranged in lines at an angle between 45 to 90 degrees of the direction of the at least one direction.

According to some embodiments of the invention, the imager includes at least one wide band sensor.

According to some embodiments of the invention, a bandwidth of the wide band sensor is at least 50% the combined bandwidth of all of the spectral sensors in the imager.

According to some embodiments of the invention, the spectral imager includes at least two narrowband filters suitable for detecting at least two different wavelength bands of the pattern.

According to some embodiments of the invention, at least one of the filters includes an interference filter.

According to some embodiments of the invention, the different wavelength bands are detected by different pixels of the imager.

According to some embodiments of the invention, pixels of the imager are covered with interference filters that match the different wavelength bands of the pattern.

According to some embodiments of the invention, at least one of the filters is tunable and is configured for detecting the different wavelength bands sequentially.

According to some embodiments of the invention, the light source includes a plurality of LEDs arrayed adjacent each other, each LED configured for emitting light at one of the different wavelength bands.

According to some embodiments of the invention, the light source is a wide spectrum light source, and wherein a set of filters suitable for transmitting the selected wavelengths are illuminated by the light source for projecting the color-coded pattern onto the scene.

According to some embodiments of the invention, the light source is a wide spectrum light source, and wherein a grating that diffracts light from the wide spectrum light source forms at least one of the components for projecting the color-coded pattern onto the scene.

According to some embodiments of the invention, the light source is a variable wavelength source.

According to some embodiments of the invention, the imager is a hyperspectral imager.

According to some embodiments of the invention, the imager is a hyperspectral imager including at least 5 spectral bands.

According to an aspect of some embodiments of the invention, there is provided a method for structured light scanning of an intra-oral scene, including projecting onto the intra-oral scene a color-coded pattern including color entities separated from each other by dark regions; acquiring and image of the intra-oral scene; and detecting the projected pattern in the acquired image of the scene; and determining one or more depths in the scene.

According to some embodiments of the invention, the dark regions are sized to reduce optical crosstalk by being large enough so as to avoid geometrical overlap between the imaged entities.

According to some embodiments of the invention, the acquiring is performed using a color imager including a Bayer filter.

According to some embodiments of the invention, the color imager is an RGB (Red Blue Green) color imager.

According to some embodiments of the invention, the color imager is an RGBI (Red Blue Green IR) color imager.

According to some embodiments of the invention, the detecting includes determining colors in the imaged pattern using the dark regions as reference.

According to some embodiments of the invention, the pattern entities comprise parallel stripes.

According to some embodiments of the invention, the pattern includes colored stripes separated from each other by dark regions in the form of stripes.

According to some embodiments of the invention, the determining includes subtracting the color obtained in a dark region from the color obtained in a stripe of interest to reduce spectral crosstalk.

According to some embodiments of the invention, the dark region includes a non-illuminated area.

According to some embodiments of the invention, the detecting includes indexing the color entities of the pattern, and wherein the dark regions define entities of the pattern which can be indexed in addition to the color entities.

According to an aspect of some embodiments of the invention, there is provided a method for structured light scanning of an intra-oral scene, including acquiring at least one image of the intra-oral scene under unstructured lighting; acquiring at least one image of the intra-oral scene under patterned lighting; and constructing a 3D model of the scene using inner-image information obtained from the image acquired under unstructured lighting and inner-image information obtained from the image acquired under the patterned lighting.

According to some embodiments of the invention, the unstructured lighting includes uniform lighting.

According to some embodiments of the invention, the method includes sequentially interchanging between the acquiring of a uniform light image and the acquiring of a patterned image.

According to some embodiments of the invention, the constructing includes identifying borders of smooth patches in the scene, the borders indicative of depth discontinuities, and wherein the smooth patches are indexed in a continuous manner.

According to some embodiments of the invention, information obtained from the image acquired under unstructured lighting is used for one or more of: coloring of the reconstructed scene, assessment of a geometry of the scene, evaluation of reflection characteristics of contents of the scene, and assessment of locations prone to loss of a projected pattern entities.

According to some embodiments of the invention, the patterned lighting includes projecting, onto the intra-oral scene, a pattern including a recurrent arrangement of parallel stripes.

According to some embodiments of the invention, the pattern includes one or more anchors.

According to some embodiments of the invention, the anchors are in the form of diagonals intersecting the stripes.

According to some embodiments of the invention, the stripes are of various widths.

According to some embodiments of the invention, the pattern includes multiple color zones.

According to an aspect of some embodiments of the invention, there is provided a method for structured light scanning of an intra-oral scene, including projecting onto the intra-oral scene a pattern including a recurring arrangement of stripes, the pattern including one or more anchors in the form of diagonals intersecting the stripes; and detecting the projected pattern in an acquired image of the scene.

According to some embodiments of the invention, the method further includes constructing a 3D model of the scene, the constructing including restoring the pattern in the acquired image utilizing the one or more anchors.

According to some embodiments of the invention, the method further includes indexing the anchors directly and further indexing the stripes or portions thereof in accordance with their spatial location relative to the anchors.

According to some embodiments of the invention, an amount of anchors incorporated in the pattern is selected in accordance with a scene variability.

According to an aspect of some embodiments of the invention, there is provided a method for depth imaging using structured light, including projecting onto a scene a color-coded pattern including an arrangement of entities; each entity including a different band of wavelengths; imaging the projected pattern as a plurality of pixels in an acquired image of the scene, using at least first and second spectral filters; wherein at least a first portion of the plurality of pixels is associated with the first filter and at least a second portion of the plurality of pixels is associated with the second filter; and wherein in the first portion of the plurality of pixels there is less than 10% contribution of the wavelength band transferred by the second filter; estimating the color of each pixel for associating the pixel with the projected color-coded pattern; and determining depth in the scene according to the associating.

According to some embodiments of the invention, the color coded pattern includes at least 5 wavelength bands and wherein each of the pixels of the acquired image is associated with one of 5 matching filters.

According to some embodiments of the invention, the pixels associated with filters are evenly distributed over an image sensor of an imager configured for acquiring the image.

According to some embodiments of the invention, the filters associated with the pixels are interference filters attached to the pixels.

According to an aspect of some embodiments of the invention, there is provided a method for structured light scanning of an intra-oral scene, including projecting onto the intra-oral scene a color-coded pattern including an arrangement of entities having edges between them; each entity including a different wavelength bands; detecting the projected pattern as a plurality of pixels in an acquired image of the scene, and differentiating between the different wavelength bands in the image by separating between at least two spectral bands; restoring the projected pattern by associating an imaged entity to a projected entity by identifying the wavelength band of the projected entity in the image wherein the at least wavelength bands are selected from the range of 400-500 nm.

Unless otherwise defined, all technical and/or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the invention, exemplary methods and/or materials are described below. In case of conflict, the patent specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and are not intended to be necessarily limiting.

Implementation of the method and/or system of embodiments of the invention can involve performing or completing selected tasks manually, automatically, or a combination thereof. Moreover, according to actual instrumentation and equipment of embodiments of the method and/or system of the invention, several selected tasks could be implemented by hardware, by software or by firmware or by a combination thereof using an operating system.

For example, hardware for performing selected tasks according to embodiments of the invention could be implemented as a chip or a circuit. As software, selected tasks according to embodiments of the invention could be implemented as a plurality of software instructions being executed by a computer using any suitable operating system. In an exemplary embodiment of the invention, one or more tasks according to exemplary embodiments of method and/or system as described herein are performed by a data processor, such as a computing platform for executing a plurality of instructions. Optionally, the data processor includes a volatile memory for storing instructions and/or data and/or a non-volatile storage, for example, a magnetic hard-disk and/or removable media, for storing instructions and/or data. Optionally, a network connection is provided as well. A display and/or a user input device such as a keyboard or mouse are optionally provided as well.

