WO2020225742A1

WO2020225742A1 - A scanning system

Info

Publication number: WO2020225742A1
Application number: PCT/IB2020/054277
Authority: WO
Inventors: Jacopo LAZZARO; Davide RANALDO
Original assignee: Playcast S.R.L.
Priority date: 2019-05-08
Filing date: 2020-05-06
Publication date: 2020-11-12
Also published as: IT201900006650A1

Abstract

A scanning system having multiple imaging devices (2; 102) of a subject to be scanned, comprising multiple scanning units (4; 104) each having: a shaped support body (6), a projection device (7; 107) and two imaging devices (2; 102). Such a scanning system (1; 101) also comprising a control and processing logic unit (10) capable of commanding the simultaneous acquisition of the images and combining them with each other to create a comprehensive three- dimensional image, the latter being created by an image joining process which uses the correspondence of emerging distinctive elements, and a photogrammetric analysis process, which determines the position data in space of the points of the images.

Description

A SCANNING SYSTEM

D E S C R I P T I O N

Field of application

The present invention is applicable in the field of measuring and detecting objects, part thereof, persons or animals and part thereof, and in particular relates to three-dimensional scans.

More in detail, the present invention relates to a three-dimensional scanning system and method.

State of the art

Different detection techniques are known in the field of three-dimensional object scanning. Laser scanner systems are mainly distinguished, devices that allow the three-dimensional reconstruction of objects thanks to the reflection of a laser beam.

Structured light systems, i.e. optical instruments whose operation relies on the reflection of light patterns on the objects to be scanned, are also known.

In particular, an application of laser scanner devices uses laser pulse scanners. The operation principle of this technique, called time-of-flight, is to measure the time between the generation of a laser signal and its reception, after the reflection on the object to be scanned. Since the magnitude of the speed of light is known, it is possible to reconstruct the object three- dimensionally.

However, the pulse laser scanner is inaccurate for time-of-flight measurements over short distances. In addition, this application is unsuitable for hardly-reflective surfaces, where it is difficult to accurately detect the edges of objects.

According to the prior art, more accurate laser scanner detectors adapted for close scanning are available to overcome such limits. Such devices generally consist of a laser light source and one or more imaging devices. After system calibration, a triangulation algorithm is used to reconstruct the three- dimensional model of the object by triangulating the positions of the laser source, the imaging device and the point on the surface of the object hit by the laser.

However, the scanning usually takes place along a laser light blade (line), thus to obtain an integral scanning of the object it is necessary to perform multiple acquisitions, moving the device or object to be scanned, so as to slide the laser light blade on the surface of the object. This movement involves long or in any case non-instantaneous scanning times.

In addition, in the case of movement of the device, the operation of such scanning systems requires the immobility of the subject to be detected for the duration of the scan, which makes such techniques difficult to use in the medical field or for other uses in which it is difficult for the subject of the scan to remain static for the necessary time.

In addition to this, the laser scanner systems require initial calibration which then affects the accuracy of the three-dimensional reconstruction.

According to the prior art, as mentioned, structured light scanning systems are also present. Generally, such devices include a light source (a projector) and an imaging device. The scanning consists of projecting a known pattern, usually parallel lines, onto an object and, by detecting how the projected image deforms when hitting the object, it is possible to determine the depth of the object and then reconstruct its three-dimensional image.

However, structured light scanning systems require the acquisition of numerous images in order to process sufficient data to reconstruct the three- dimensional model of the object. Therefore, like laser scanner systems, long scanning times are required, during which time the subject must be immobilized.

Furthermore, also the structured light systems allow only portions of the subject to be scanned. Accordingly, in order to acquire integral images and reconstruct a complete three-dimensional image it is necessary to move the scanning device around the subject or to advantageously move the subject.

Moreover, another drawback that affects all the scanning systems described so far is that they have dimensions adapted to the typical dimensions of the subjects to be scanned. It follows that if the user has to scan subjects of very different dimensions, he must have several scanning systems. Presentation of the invention

The object of the present invention is to provide a scanning system that allows at least partially overcoming the drawbacks highlighted above.

In particular, an object of the present invention is to provide a scanning system adapted to scan subjects difficultly predisposed to immobility.

Another object of the present invention is to provide a scanning system that does not require the movement of the system itself or of the subject to be scanned in order to perform an integral scan of such subject.

In other words, an object of the present invention is to provide a scanning system in which such an operation is performed in a single instant, whatever the size of the subject to be scanned.

A further object of the present invention is to provide a scanning system which does not require initial calibrations.

Another object of the present invention is to provide a scanning system usable for the scanning, also integral, of subjects having any dimensions.

Said objects, as well as others which will become clearer below, are achieved by a scanning system according to the following claims, which are to be considered as an integral part of this patent.

In particular, the scanning system has two or more imaging devices of a subject to be detected and includes one or more scanning units.

Subject to scan refers to the whole body of an individual, animals, objects or parts thereof such as, by way of example only, arms and/or forearms.

Each unit includes a shaped support body to which at least two types of devices are coupled: at least one projection device, for projecting a light beam onto a subject to be scanned, and one or more imaging devices, for acquiring images of this subject.

According to an aspect of the invention, the scanning system also comprises a control and processing logic unit.

This logic unit is configured at least to command the imaging devices to simultaneously acquire images of the subject to be scanned. Following the acquisition, the logic unit combines the images with each other to create an overall three-dimensional image of the subject. According to another aspect of the invention, the aforementioned combination of images is made by a joining process which uses the correspondence in the images of distinctive elements emerging by means of the light beams projected on the subject. There is then a photogrammetric analysis process by which the position data in space of the points of the acquired images are determined so as to give three-dimensionality to the overall image.

The scanning system of the invention thus allows, by simultaneous imaging and the subsequent combination and analysis, to reconstruct a comprehensive three-dimensional image of the subject to be scanned.

Advantageously, the simultaneous imaging commanded by the logic unit allows the system to instantaneously scan the subject. Thus, still advantageously, it allows to scan subjects regardless of their predisposition to immobility.

Furthermore, still advantageously, the simultaneous imaging avoids the obligation to move the scanning units or the subject of the images, if an integral scan is performed.

Still advantageously, the image joining process and the photogrammetric analysis process performed by the logic unit allow the scanning system to be predisposed to the imaging of the subject without the need for an initial calibration that consequently influences the accuracy of the scan.

According to another aspect of the invention, the aforementioned scanning units comprise coupling means adapted to removably associate them with each other.

Advantageously, the possibility of removably coupling the scanning units through coupling means allows the system itself to be easily modified. In fact, it is sufficient to associate an adequate number of scanning units with each other to scan any type of subject regardless of its size without having to buy different scanning systems.

From that which is stated above, it is evident that said objects are achieved also by a scanning method comprising the following steps:

at least one step of projecting a light beam onto a subject to be scanned; at least one step of simultaneous acquisition of two or more images of the subject to be scanned;

at least one processing step adapted to combine the images with each other to produce a comprehensive three-dimensional image of the subject to be scanned, said processing step providing a process of joining the images using the correspondence therein of distinctive elements emerging by means of projected light beams, and a photogrammetric analysis process for determining the position data in space of the points of the images.

Brief description of the drawings

Further features and advantages of the invention will be more evident in light of the detailed description of some preferred, but not exclusive, embodiments of a three-dimensional scanning system and method according to the invention, illustrated by way of non-limiting example with the aid of the accompanying drawings, wherein:

FIG. 1 represents a scanning system according to the invention in a semi transparent view;

FIG. 2 represents an embodiment of the invention;

FIG. 3 represents a detail of the embodiment of fig. 2.

Detailed description of some preferred embodiments

With reference to the above-mentioned figures, and in particular to fig. 1 , described herein is a scanning system 1 according to the invention. It has two imaging devices 2 of a subject to be scanned. Subject to be scanned refers to the whole body of an individual or animals, or parts thereof such as, by way of example, arms and/or forearms. Furthermore, the invention can also be used for imaging objects or portions thereof.

Obviously, this aspect should not be considered limiting for different embodiments of the invention, where, for example, the scanning system comprises multiple imaging devices.

In the embodiment of the invention being described, the two imaging devices 2 are inserted in a scanning unit 4.

According to an aspect of the invention, the scanning unit 4 includes a shaped support body 6. It is coupled to a projection device 7 for projecting a light beam onto the subject to be scanned. In addition, the two imaging devices 2 are also coupled thereto. Obviously, these aspects should not be considered limiting for different embodiments of the invention, where the number of projection devices and imaging devices coupled to the scanning unit is different from the above.

According to another aspect of the invention, the scanning system 1 comprises a control and processing logic unit 10. This logic unit 10 is capable of commanding the imaging device 2 for the simultaneous imaging of the subject.

In addition, according to a further aspect of the invention, the logic unit 10 is programmed to combine the acquired images so as to create a comprehensive three-dimensional image of the subject to be scanned. In particular, the combination of the images is done through a joining process, which uses the correspondence of the projected light beams in the images, and by a photogrammetric analysis process which determines the position data in space of the points of the acquired images.

Advantageously, the simultaneous imaging controlled by the logic unit 10 allows the system 1 an instantaneous scan of the subject regardless of the predisposition to immobility of the latter.

Still advantageously, the image joining process and the photogrammetric analysis process performed by the logic unit allow the scanning system to be predisposed to the imaging of the subject without the need for initial calibrations that consequently influence the accuracy of the scan.

Furthermore, still advantageously, the simultaneous imaging avoids the obligation to move the scanning system 1 or the subject of the images.

As regards the projection devices 7, in the embodiment described, they consist of laser projectors. These laser projectors project a graphic elaboration on the subject to be scanned, this graphic elaboration constitutes the distinctive elements that allow the logic unit 10 to combine the acquired images so as to create a comprehensive three-dimensional image. Furthermore, the imaging devices 2 are formed by cameras. Obviously, these aspects should not be considered as limiting for different embodiments of the invention, where the same functions are performed by different devices. In one embodiment of the form described, the projection devices 7 consist of light projectors of any colour and intensity. The light projectors allow to illuminate the subject to be scanned, making it possible to identify the distinctive elements, consisting of the unique features present on the surface of the subject itself, and therefore to combine the acquired images with each other to create a comprehensive three-dimensional image of the subject.

The embodiment described herein comprises a single scanning unit 4. This aspect should not be considered limiting for different embodiments of the invention, where the scanning system comprises multiple scanning units.

In this sense, fig. 2 represents an embodiment of the invention where the scanning system 101 consists of six scanning units 104. In particular, each scanning unit 104 comprises two imaging devices 102 and a projection device 107. However, such features, as already mentioned, should not be considered limiting for different embodiments of the invention where the number of projection and imaging devices per scanning unit are in different numbers. In this sense, it is useful to point out that a particular embodiment, not shown in the figures, provides for the presence of only one imaging device per scanning unit. Further particular embodiments, also not represented, provide for the combined use of scanning units each equipped with a different number of imaging devices and projection devices.

It is thus advantageously observed that there can be any number of scanning units. This aspect advantageously allows using a number of scanning units adapted to the size of the subject to be scanned.

Still advantageously, it is not necessary to have different scanning systems to be able to scan subjects with different dimensions, it being sufficient to use an adequate number of scanning units from time to time.

Still advantageously, the combination of multiple scanning units allows for the simultaneous acquisition of all the images necessary for the scan regardless of the size of the subject, without having to move the latter or having to move the scanning system.

In all cases, the logic unit commands the simultaneous acquisition of the images to all the imaging devices comprised in the system and then combines and defines the position of the points in space of all the acquired images, creating a comprehensive three-dimensional image.

Also the number of logic units present in the scanning system of the invention is a non-limiting feature, since they can have any number and coordination with each other.

In order to facilitate the coupling between the scanning units 104, according to a further aspect of the invention the scanning system 101 comprises coupling means 112 adapted to removably associate the scanning units 104 with each other.

Advantageously, the possibility of removably combining the scanning units 104 through coupling means 112 allows them to be assembled with each other in correct and optimal reciprocal positions.

Furthermore, it is easy to modify the scanning system, making it possible to immediately associate any number of scanning units.

According to the embodiment of the invention being described, such coupling means 112 comprise a joint 113 also observable in fig. 3. It is configured to detachably couple on one side 114 to a scanning unit 104 and on the opposite side 115 to another scanning unit 104.

Obviously, this aspect should not be considered limiting for different embodiments of the invention, where, for example, the coupling means are formed by a special structure, possibly modular, to which to couple the scanning units.

Still, according to further embodiments of the invention not shown in the figures, the coupling means consist of special shapes of the ends of the shaped body of the scanning units so as to allow them to be directly coupled in series, possibly of the male/female type.

However, it is evident that the object of the patent is also a scanning method adapted to be performed by the scanning system 1 described above.

In particular, it comprises a projection step in which the projection device 7 projects a light beam onto a subject to be scanned.

Then there is a simultaneous imaging step commanded by the logic unit 10 to all the imaging devices 2. Advantageously, therefore, the imaging necessary for the scan takes place in a single instant, solving any mobility problems of the subject to be scanned. In addition to this, still advantageously, the obligation to move the scanning units or the subject to be scanned to obtain the complete scan is avoided.

According to another aspect of the invention, the method then comprises a processing step where the combination of the acquired images with each other takes place to create a comprehensive three-dimensional image of the subject.

In this processing step there is an image joining process, which uses the correspondence of the light beams projected on the images, and a photogrammetric analysis process to determine the position data in space of the points of the images.

Advantageously, the image joining process and the photogrammetric analysis process make it possible to avoid an initial calibration of the scanning system 1 that consequently affects the accuracy of the comprehensive scan.

In light of the foregoing, it is understood that the scanning system of the invention achieves all the prefixed purposes.

In particular, the scanning system of the invention performs this operation in a single instant, and is adapted to scanning, also integrally, subjects having any dimensions.

Furthermore, the scanning system of the invention is adapted for scanning subjects regardless of their predisposition to immobility.

On closer inspection, moreover, the scanning system of the invention avoids the obligation to move the scanning units or the subject itself.

It is also noted that the scanning system is predisposed to imaging the subject without the need for an initial calibration that could negatively affect the accuracy of the scan.

The invention might be subject to many changes and variants, which are all included in the appended claims. Moreover, all the details and steps may furthermore be replaced by other technically equivalent elements, and the materials may be different depending on the needs, without departing from the protection scope of the invention defined by the appended claims.

Claims

C L A I M S

1. A scanning system having two or more imaging devices (2; 102) of a subject to be scanned, said scanning system (1 ; 101) comprising one or more scanning units (4; 104) each having:

a shaped support body (6);

at least one projection device (7; 107) coupled to said shaped body (6) for projecting at least one light beam on the subject to be scanned;

at least one of said imaging devices (2; 102) also coupled to said shaped body (6),

said scanning system (1 ; 101 ) also comprising a control and processing logic unit (10) capable of at least:

commanding the simultaneous acquisition of said images to said two or more imaging devices (2; 102);

combining said images with each other to create a comprehensive three-dimensional image of the subject to be scanned, said combination being made by a process of joining said images using the correspondence in said images of distinctive elements emerging through said projected light beams, and a photogrammetric analysis process that determines the position data in space of the points of said images.

2. Scanning system according to claim 1 , wherein said scanning units (104) comprise coupling means (112) adapted to removably associate two or more of said scanning units (104) with each other.

3. Scanning system according to claim 2, wherein said coupling means (112) comprise a joint (113) configured to be removably coupled on one side (114) to one of said scanning units (104) and on the opposite side (115) to another of said scanning units (104).

4. Scanning system according to claim 2, wherein said coupling means comprise shapes of the ends of said shaped body of said scanning units so as to allow for the removable coupling in series with other shaped bodies of other scanning units.

5. Scanning system according to claim 4, wherein said shapes allow a male/female type coupling between said shaped bodies.

6. Scanning system according to any one of the preceding claims, wherein said projection device (7; 107) is a laser projector.

7. Scanning system according to any one of claims 1 to 5, wherein said projection device is a light projector.

8. Scanning system according to any one of the preceding claims, wherein said imaging devices (2; 102) are cameras.

9. Method for scanning three-dimensional objects comprising:

at least one step of projecting at least one light beam onto a subject to be scanned;

- at least one step of simultaneous acquisition of two or more images of the subject to be scanned;

at least one processing step adapted to combine said images with each other to create a comprehensive three-dimensional image of the subject to be scanned, said processing step providing a process of joining said images using the correspondence in said images of distinctive elements emerging by means of projected light beams, and a photogrammetric analysis process for determining the position data in space of the points of said images.