WO2011032238A1

WO2011032238A1 - Device and method for 3d scanning

Info

Publication number: WO2011032238A1
Application number: PCT/BG2010/000012
Authority: WO
Inventors: Юрйи РАДКОВ; Костадин ВРАНТЗАЛИЕВ
Original assignee: Radkov Juriy; Vrantzaliev Kostadin
Priority date: 2009-09-17
Filing date: 2010-08-31
Publication date: 2011-03-24

Abstract

This invention is designed to visualize on a real object results from 3D scanning. The device consists of a 3D scanner manipulated by operator which includes computing device, at least one measuring element and scanning software and includes portable projector for visualizing the scan data on the physical object; and mixed reality software for scan data processing and data generation for the projector. The method includes separate cycles in which the 3D scanner measures and generates scan data, the mixed reality software receives and processes scan data at certain periods of time, while at another period of time the mixed reality software sends to the projector a graphical image of the scan data which is then projected on the surface of the object being scanned so as to obtain a spatial match of the scan data displayed graphically by the projector and the actual surface such data are referring to.я

Description

3D scanning device and method

Description Technical field

The present invention finds application for accurate 3D scanning in the field of engineering and automotive industries, medicine, film production and the advertising industry, museum and cultural history, etc. The collected 3D scanning data can be used to create a spatial (three-dimensional) model of the object, which can be used for many applications, such as reengineering, copying and editing forms, objects; measuring complex shapes and distances; inspections (comparisons) with reference digitalized objects or CAD models; renderings, animations, etc.

Prior art

When scanning 3D, the shape of the scanned object is digitalized by measuring the spatial coordinates, and possibly the color of the set of points lying on the surfaces of the objects. The currently familiar 3D scanning devices are divided into two main types: contact and non-contact. Contact scanners measure points on the surface by physical contact using a contact sample, while non-contact scanners count on radiation or different types of light, X-rays, infrared light, etc., and sensors that take into account reflections from the measured object.

Often 3D scanners include spatial position-tracking devices called localizers, which take into account the spatial position and orientation of the measuring element of the scanner, the frequency of which is often several hundred times per give me a sec. Thanks to this in-house functionality, localizers provide the ability to scan from different angles and positions.

Bypassing the scanned object can be done by automatically or manually moving the measuring element, and combining data from the measuring object with data from the localizer results in the coordinates from the measurements in the same spatial coordinate system. There are different types of localizers, such as mechanical horizontal and articulated (which have many rotating joints) hands, CNC machine localizers with a distant position report based on radiation or reception of an impulse, light, signal; optical localizers, electromagnetic localizers, GPS systems, etc. Optical localizers include solutions for calculating the change in the position of the measuring element by monitoring on the optical principle of markers on the scanning object or its environment, or by processing images of the object or its environment, selected while the measuring element was moving from statically suspended from it or to the surrounding environment of devices for selecting images (like a video camera).

Since some types of 3D scanners require that the distance between the measured surface of the object and the measuring element be within some boundaries (in the range), to facilitate the operator, individual indications have been developed to mark the fact to what extent the current distance is within this range. These indications may be in the form of graphical information on the screen, or in the form of an audio or visual indication. An example of graphical information is a display of current measurements in points in a specialized software that displays their three-dimensional values (Geomagic Studio ™ - Geomagic Inc, Polyworks ™ - Innovmetric Inc, KUBE ™ - Metris NV). An example of a visual indication of the validity of a range is the ModelMaker ™ of the Metris NV scanner, which in addition to the laser line obtained by the intersection of the scanning laser plane with the real object and visible on it, it still emits a laser beam at an angle to the plane of the plane, which intersects with the plane at the optimum distance for scanning. As a result, at the optimum distance between the object and the measuring element, a laser line and a laser point are visible on the object, which are close to each other; when changing the distance to the side from the optimal, the more the distance differs from the optimal, the more the distance between the line and the point increases.

The 3D scanning process is usually an interactive process, when the image on the screen determines the subsequent actions of the operator, and a typical example of this is determining the path to bypass the scanned object, depending on what were successfully scanned areas at the moment. The data received at the moment from the scan will be displayed on the screen in the form of 3D graphics, and in practice it turns out that the scanned parts receive the image, and the unscanned ones are missing. Based on the lack of this data, the operator decides which physical area of the object should be scanned. 3D graphics provide the ability to rotate, move and enlarge an object on the screen, which allows the operator to better identify the scanned sectors. The inconvenience in the case is the need to interrupt the scanning process and use the periphery of the computer (keyboard, mouse, joystick, etc.) to manipulate three-dimensional graphics. The software of some systems, such as the KUBE ™ software of the ModelMaker ™ scanning 3D system - Metris NV, allows using the localizer of the scanning system as an interactive device for manipulating the image of an object on the screen, thereby partially compensating for the aforementioned inconvenience.

The above types of visualization require the operator to simultaneously monitor both the scanned object and the image on the screen, meanwhile, comparing the object and the screen in order to find a match between the areas shown on the screen and corresponding areas of the real object, which requires certain skills of spatial thinking.

There are many developments for mixing physical objects with virtually created images, the so-called MIXED REALITY (Mixed Reality). WO 049282 describes a device for designing an existing virtual object on a corresponding physical object. The proposed solution is suitable in cases of a pre-existing virtual model and a static position of the designing visualizing device. The problem of using one or more static projectors is the inability to generally project onto some parts of the surface of an object, since there may be areas that are obscured by projectors.

US 6,764,185 discloses the design of a computer image on a real object for the purpose of interaction, and includes the use of a camera, a sensor for tilting and accelerometers, but not localizers. This patent is also limited to the use of directional arrows on the object, but not to show the degree of "overlap" and the results of actions of one scanning system. The technical essence of this invention

The present invention is intended to render 3D scanning results on a real object using an operator-controlled three-dimensional scanning system. The main feature of this device and 3D scanning method presented in the present invention is that the obtained data from the scan receive visualization on the physical object that is being scanned. Thus, the need to use a monitor or other device to visualize the scan results is reduced, and at the same time, this process depends to a lesser extent on the skills of the operator. In fact, this invention provides a simplification of the process of working with 3D scanning systems. The present invention is a device for scanning 3D, which consists of a 3D scanner, serviced by the operator, which includes:

- at least one computing device with memory;

- at least one measuring element;

- software for scanning,

characterized in that it includes:

- a portable projector connected to a computing device that visualizes scanned data on a physical object;

- software for mixed reality (mixed reality software) for processing scan data and for generating data about the projector;

In the case of a specific embodiment of the invention, the 3D scanner also includes at least one localizer connected to a computing device that monitors the position of the reference element predefined by the manufacturer.

In the case of another specific embodiment of the present invention, the measuring element is connected stationary to the localizer.

In the case of another specific embodiment of the present invention, the projector is fixedly connected to the localizer.

In the case of another specific embodiment of the present invention, the projector is integrated into the measuring element.

In the case of a further specific embodiment of the present invention, the device also includes a second localizer that monitors the position of the manufacturer-defined reference element that is connected to the computing device.

In the case of another specific embodiment of the present invention, the projector is fixed motionless in relation to the reference element of the second localizer. The present invention also provides a 3D scanning method, which includes separate cycles when the 3D scanner takes measurements and generates scanned data, characterized in that:

a) software for mixed reality receives and processes scan data after a certain time interval;

b) after another certain period of time, the software for mixed reality supplies the projector with a graphic image of the scan data, which is projected onto the surface of the scanned object in the form of a projection in such a way that a spatial coincidence of the scan data graphically depicted by the projection and the real surface to which they refer is obtained.

In one particular embodiment, to generate a graphic image, the method involves using the position of the projector in relation to the global coordinate system at the time of image visualization.

In another specific embodiment, to determine the position of the projector with respect to the global coordinate system, the method involves using one or more localizer positions when the projector is fixed.

In the next specific design, to determine the position of the projector with respect to the global coordinate system, parameters are used that were calculated in advance during the preliminary registration process, which includes searching and storing in memory the relative position of the projector with respect to the reference element of the localizer to which the projector is fixed, or in the absence thereof localizer with respect to the global coordinate system.

In the next specific embodiment, parameters generated by the preliminary calibration process, which includes searching and storing the projector’s parameters in memory in accordance with the chosen mathematical model of the transformation between the three-dimensional space and the projector supplied for visualization in a two-dimensional way, are used to generate a graphic image. In the next specific embodiment, when the projector is moved, the displayed graphic image changes often enough to preserve the visual spatial coincidence of the scan data graphically displayed by the projection and the real surface to which they relate.

In the particular case, the 3D scanning method described herein is applied through the device of the present invention.

Description of attached drawings

Figure 1 Example 1 of the invention.

Figure 2 Example 2 of the invention.

Figure 3 Example 1 of the invention using specific constituent elements.

Figure 4 The design scheme of the image of the scanned object through the device according to the present invention.

Figure 5 Positions at the approximate stages of registration and calibration of the projector.

Figure 6 Diagram of example 1 with a projector integrated in the measuring element.

Figure 7 Example 1 of the invention with specific constituent elements using a localizer with a remote position report

Figure 8 Implementation and scheme of work with the device according to example 2 using specific components using localizers with a remote position report.

Figure 9 The scheme of work with the implementation of the device according to the figure

6.

Examples for execution

For the purposes of this description, all devices and methods for calculating the momentary physical spatial position (position) of any object (for example, a measuring element, a projector) with respect to any other object expressed in a specific coordinate system will be called localizers.

For the purposes of the present description, spatial measurements obtained during scanning and / or spatial data associated with them (as a reference object), and / or additional information obtained using scanning data, such as the displacement of the scanned surface relative to the reference object, will be called scan data. Scan data can be the entire set or subset of data accumulated during the scanning process, include information about the mode and condition of the system, as well as any other information related to the scanning process.

For the purposes of the present description, by the definition of “graphic” we mean the presented image using color or monochrome drawing of dots, triangles, polygonal lines, geometric primitives, analytically defined mathematical surfaces and other mathematical and geometric representations of surfaces and volumes.

For the purposes of the present description, contact probes and sensors reporting displays will be called measuring elements.

Figure 1 shows an exemplary embodiment of the invention 1 (example 1).

The 3D scanning device consists of a 3D scanner (100), a portable image projector (1), a computing device (computer) (6), software for mixed reality (7).

The 3D scanner (100) includes the following elements: one measuring element (3), one localizer (21), software for scanning (15).

The 3D scanner (100) is connected to the computing device (6).

The 3D scanner (100) must be set up so that the scanned data are aligned with respect to the space defined by the consumer - the global coordinate system (11). The localizer (21) (according to the manufacturer’s design) monitors the position of the reference element predefined by the manufacturer (91) and is adjusted (calibrated) in such a way as to provide the spatial position of the reference element (91) relative to the global coordinate system (11), and this spatial position we will call the position of the localizer (21).

The projector (1) is fixed stationary with respect to the reference element (91), and the mount can be external using the fastening elements (16), as shown in Figure 3, or by integrated mounting in the measuring element, as shown in Figure 6. Most often they achieve maximum efficiency during installation when they reach the maximum coverage of the working volumes of the projector (1) and the measuring element (3).

The projector (1) is connected to a computing device (6).

In the preliminary procedure, the relative position of the projector (1) with respect to the reference element (91) of the localizer (21) was found, and we will call this relative position registration, and the procedure for its search is registration.

In addition to the registration search procedure, preliminary preparation of the system also includes a procedure for calculating the parameters of the projector (1) in accordance with the chosen mathematical model for representing the transformation between the three-dimensional space and the projector supplied for visualization with a two-dimensional image. We will call these parameters calibration; the procedure for their calculation is called calibration. The simplest transformational model is the standard mathematical perspective projection, which, depending on the lenses used for the projector (1), may turn out to be a fairly accurate model. There are various advanced models for the representation of cameras, with which you can more accurately model the projector (1) (camera models can also be accepted as models of projectors, since they model the same interdimensional transformations). With the Tsai model, for example, in addition to perspective projection, modeling parameters of distortion from lenses have been added. Depending on the projector used, the intended operating range and accuracy, the limitations of calibration procedures and other factors, different transformation models can be used.

In the operating mode of the device according to the present invention, the 3D scanner (100) works in such a way as it would and as a standalone 3D scanning device, but in addition the scanning software (15) sends the scanning data in any of the measurement cycles or at time intervals to the mixed software reality (7). An operating mode is also possible when the 3D (100) scanner does not send scan data, but the remaining components of the system operate as described below.

Also, after a certain time interval, the software (7) receives directly from the localizer (21) through the means of communication or with the help of the scanning software (15) the moment position of the localizer (21). Softwer (7) pre-charged the calibration and registration data of the projector. Softwer (7) uses data on the moment position of the localizer and registration of the projector in order to calculate by applying spatial transformations the moment position of the projector relative to the global coordinate system (11). Using data on the momentary position of the projector and calibration data on the parameters of the projector, software (7) creates a graphic image (8) that is fed to the image by the projector (1) on the surface of a real object (12) in the form of a projection (13) in such a way that for a specific of the projector's moment position, a spatial coincidence of the scan data graphically depicted by the projection (13) and the real surface (12) to which they relate is obtained.

Image (8) was created using geometric projection from three-dimensional in two-dimensional space, the position and orientation of which in the global coordinate system (11) coincide with the moment the spatial position of the projector (1), and the type and parameters of which coincide with those of the calibration. As a result of this, after the geometric design of spatial coordinates from the scan data from the surface (12) onto the image surface plain (8) and the subsequent reverse projection of the image (8) onto the surface (12) by the projector (1), the location in the real space of the designed virtual surface and the real surface (12).

As a result, it becomes possible at a certain position of the projector (1) to depict on a real object (12) a projection (13) that graphically visualizes scan data relating to the area of a real object (12) specifically covered by the projection (13).

Image (8) needs to be regenerated often enough so that with normal projector movement in space, projection (13) does not visibly diverge from the corresponding surface of the object (12). The frequency of renewal (regeneration) of the image (8) approximately 25-30 times per second is quite sufficient.

In order to improve the accuracy of the correspondence between projection (13) and surface (12), data on the spatial position of the projector (1) can be used for more accurate calculations of the moment position of the projector (1) at the moment of projection image (13) by accumulating data on the movement of the projector (1 ) and extrapolating its expected position after a certain time interval, for example, after the time it takes to create an image (8). This would help to overcome the mismatch between the projection (13) due to the displacement of the projector from the time when information about its position was received until the projection was visualized (13). Data on the moment speed and direction of movement of the projector (1) can also be used to determine the validity time of a given image (8), the latter can be calculated on the basis of how long it is expected that the projector (1) would be in such spatial position so that the projection (13) coincides in acceptable boundaries with the corresponding surface (12).

Figure 2 shows one embodiment of the device according to the present invention (example 2). It consists of a 3D scanner (100), which includes: a measuring element (3), a localizer (21) connected to the measuring element (3) and to a computing device (6) on which the scanning software (15) is installed. The localizer (21) monitor the position of the reference element predefined by the manufacturer (91) and calibrated so as to provide the spatial position of the reference element (91) with respect to the global coordinate system (11).

The projector (1) is connected to the localizer (22), which monitors the position of the reference element predefined by the manufacturer (92). Unlike the localizer (21), which was part of the 3D scanner, the localizer (22) is an independent component that is separate from the 3D scanner. The localizer (22) is connected to a computing device (6), on which the software for mixed reality (7) is installed. Computing device (6) may consist of one or more computers.

The projector (1) is fixed motionless with respect to the reference element (92) of the localizer (22).

Using the same procedures as for the device in Figure 1, the projector (1) must be registered in space with respect to the localizer (22) in such a way that with the localizer (22) the spatial position of the projector (1) with respect to the global system coordinates (11) could be determined at any time. In addition to registration, the preliminary preparation of the system also includes groove calibration of the projector, as described below.

The device in Figure 2 works in the same way as the device in Figure 1, with one exception. In order to determine the spatial position of the projector (1), a localizer (22) is used, which is an independent component selected from the 3D scanner. Figure 5 shows an example calibration and recording method based on the use of a conventional perspective projection for a transformation model. A calibration plane (41) is used, on which there are engraved parallel rectangles (42) with aspect ratios corresponding to the proportions of the projector image (e.g. 4: 3 or 16: 9). There are two rectangles (42) - larger and smaller, their centers coincide, and there are designations of direction indications (e.g., up and to the side) that are parallel to their sides. The vertices of the rectangles (42) are measured using a 3D scanner (100), so as to obtain their coordinates in the global coordinate system (11). The measurements are carried out in a specific order with respect to the size of the rectangles (42) (for example, first smaller, then larger) and in relation to direction indications (e.g. lower left corner, lower right corner, upper right corner, upper left corner). The projector (1) is turned on in the image mode of an image containing a rectangle with image dimensions and direction indications similar to those drawn on the calibration plane and parallel to the sides of the image. The projector (1), the operator positions so that the projection of the image on the calibration plane (41) coincides with one of the rectangles engraved in the calibration plane (42), and make sure that the indication of directions coincide (position 1). The coincidence of the direction indications guarantees the correct creation of a correspondence between the vertices of the image rectangles and the rectangles (42) of the calibration plain plane (41). If the rectangle of the image projection coincides with one of the rectangles (42) of the calibration plane (41), they take the position of the localizer (21) - position 1, after which the operator positions the projector (1), respectively, the projection onto the other of the rectangles (42) (bypassing the rectangles (42) follows a predefined order) and again, when the coincidence of the rectangle of the image with the rectangle of the calibration plane (41) is reached, the position of the localizer (21) is taken - position 2. The data selected in this way were obtained with the orthogonal position of the projection direction to the calibration plane (41), and they provide a method for calculating the perspective projection (calibration) angle and spatial position (registration) of the projector (1) with respect to the reference element of the localizer (21). For this purpose, it is assumed that position 1 is basic, and only the coordinates with respect to the reference element of the localizer (21) in this position will be called the basic coordinates.

The vertices of the rectangles (42) of the calibration plane (41) are transformed from global to base coordinates. The displacement (translation) between position 1 and position 2 is calculated, and translation of the same magnitude in the direction coinciding with the design direction is applied to the base coordinates of the vertices of the second of the rectangles (42) (the design direction is orthogonal for the calibration plane (41), and the two-valued directions are decided by using vertex traversal order). After applying the aforementioned translations, the basic coordinates of the vertices of the rectangles (42) lie on the pyramid, the vertex of which is the center of the perspective projection of the projector (1), and whose sides determine the projection volume, and, accordingly, the projection angle. Calculation of the pyramid is a solvable trigonometric problem, and the results give registration (spatial position of the pyramid in basic coordinates = position of the projector (1) with respect to the reference element of the localizer (21)) and calibration (projection angle for this model).

The registration and calibration option proposed in this way is one of the possible solutions; many others could facilitate the practical implementation of the procedure and / or improve the accuracy of registration and calibration calculations. It is possible to develop registration and calibration procedures in which the number of measurements is not limited to only two, but a larger number of positions are measured. If there are more measurements, it is possible to use optimizing methods to minimize errors. Reference _ registration and calibration can be limited not only to plain-planar rectangles, but other objects can also be used. In practice, tricks are also familiar when the designed images can be measured using other devices (for example, cameras or video cameras), and thanks to image processing methods, coordinates can be determined in the necessary reference coordinate system.

An important factor for the projection quality of some projectors is the distance to the projected object, since they operate in a limited focus range. For such projectors, the focus range is usually set by manual focusing, and when changing the focus, it is necessary to calculate the projector calibration again in order to update the parameters of the projection model. This requires that, prior to calibration, adjust the focus of the projector so that it covers the maximum desired working range of the projector, which, in turn, requires that calibration be carried out within the same range. For projectors for which it is possible to change the focal length using software, it is possible to make different calibrations for the corresponding focus ranges, as well as to enter their automatic use when changing the focus (a suitable focus range can be calculated when creating an image for the projection). Over the past years, projectors have been developing for which the focal length does not change (for this purpose, not ordinary light sources are used, but laser light sources), and for them the problem of focal length does not exist.

The following are examples of specific versions of the device using existing components, as follows:

• The device, which consists of a 3D scanner, using an articulated arm with a linear laser measuring element (MCA ™ with ModelMaker ™ - Metris NV) and a projector (MProl 10 ™ - ЗМ) mounted externally on the arm is shown in Figure 3. The device, which consists of a 3D scanner with remote position reporting and a linear laser measuring element (HandyScan ™ - Creaform Inc.) and with an integrated projector (PicoP Display Engine ™ - Microvision), is shown in Figure 7.

The device, which consists of a 3D scanner with an optical localizer and a linear laser measuring element (K-Scan MMD - Metris NV) and a portable projector (MProl lO ™ - ЗМ) on a separate optical localizer, is shown in Figure 8. Application of this invention

The collected 3D scanning data can be used to create a spatial (three-dimensional) model of the object, which can be used for many applications, such as re-engineering, copying and editing the shape of objects; measuring complex shapes and distances; inspections (comparisons) with reference digitalized objects or CAD models; for visualization, animation, etc.

The presented invention allows for interactive 3D scanning to depict current results physically on the surface of the scanned object for which this information relates, and this image is used by the operator to determine how to continue the scanning process. This invention solves to a large extent the problem of the need for the operator to mentally find the three-dimensional graphic data on the screen (VDU) and the surfaces of the object itself. The operator can direct the projector to each surface of interest, which is an alternative to rotating or moving the scanned image on the screen. There is the possibility of continuous operation with the 3D scanning device and there is further visibility in cases where it is impossible to install the screen in such proximity to the operator in order to see the details sufficiently. The presented technical solution is an alternative for screens for heads (HMDs) that limit the visibility of the real situation and / or have insufficient resolution for 3D scanning purposes.

An application example is the instantaneous visualization of scanned points from the surface of an object onto a scanned surface, and thus the operator is provided with unambiguous information regarding the success of the scan. In the case of a suitably mounted projector relative to the range of the 3D measuring element, it is possible to overlap the working volumes of the projector and the measuring element, so that simultaneously with the scan, you can also project the data that will be received onto the physical area that is being scanned.

Another example of the application of this invention is an instant inspection (check) of deviations of a physical object from its expected shape given by its standard (e.g., CAD model). Thanks to software solutions offered by the manufacturers of scanners or software for 3D scanners themselves, the 3D scanner can work in a mode in which it is possible to calculate the deviation of the measured points from their expected position in the standard. Based on this deviation, positive or negative, information can be presented in colors (for example, red means a positive deviation from an object outside tolerances, green means within certain tolerances, blue a negative deviation from an object outside tolerances). The device of the present invention makes it possible to instantly display this color information on the object itself. Description of symbols used

1 Projector

3 Measuring element

6 Computing device

7 Software mixed reality

8 Graphic created by software 7

11 Global coordinate system Surface of a real object

Projection on a real object

Software scan

Projector Mounts

Localizer 1

Localizer 2

Calibration plane

Rectangles on the calibration plane

The reference element of the localizer 21

Reference element localizer 22

3D scanner

Claims

Device and method for scanning 3D Claims

1. The 3D scanning device, which consists of a 3D scanner (100), a manipulated operator, which includes at least one computing device (6) with memory, at least one measuring element (3) and software for scanning (15),

characterized in that it also includes:

- a portable projector (1) connected to a computing device (6) that visualizes the scanned data on a physical object (12); and

- software for mixed reality (7) for processing data from scanning and for generating data and transmitting them to the projector (1).

2. The device, according to claim 1, characterized in that it also includes a localizer (21) connected to a computing device (6), monitoring the position of the reference element predefined by the manufacturer (91).

3. The device, according to claim 2, characterized in that the measuring element (3) is fixed motionless to the localizer (21).

4. The device, according to claim 2 or 3, characterized in that the projector (1) is connected stationary to the localizer (21).

5. The device, according to claim 3, characterized in that the projector (1) is integrated into the measuring element (3).

6. The device, according to claim 1, 2 or 3, characterized in that it includes a localizer (22) connected to the computing a device (6) that monitors the position of the manufacturer-defined reference element (92).

7. The device, according to claim 6, characterized in that the projector (1) is fixed motionless with respect to the reference element (92) of the localizer (22).

8. The 3D scanning method, which includes separate cycles, when the 3D (100) scanner takes measurements and generates scanned data, characterized in that:

a) software for mixed reality (7) receives and processes scanned data at a certain time interval; and

b) after another certain period, the software for mixed reality (7) gives the projector (1) a graphic image of the scanned data, which is projected onto the surface (12) of the scanned object in the form of a projection (13) in such a way that a spatial coincidence of the graphically depicted projection (13) is obtained ) of scanned data and the real surface (12) to which they relate.

9. The method according to claim 8, characterized in that the position of the projector (1) with respect to the global coordinate system (11) at the time of image visualization is used to generate a graphic image (8).

10. The method according to claim 8 or 9, characterized in that for determining the position of the projector (1) with respect to the global coordinate system (11), one or more localizer positions are used, to which the projector (1) is fixed.

11. The method according to claims 8-10, characterized in that for determining the position of the projector (1) with respect to the global system of coordinates (11), parameters are used that were calculated during the preliminary registration process, including searching and storing in memory the relative position of the projector (1) with respect to the reference element of the localizer to which the projector is fixed, or in the absence of such a localizer with respect to the global coordinate system (eleven).

12. The method according to claims 8-11, characterized in that the parameters calculated in advance during the preliminary calibration process, which includes searching and storing the projector parameters (1) in memory in accordance with the selected mathematical model for representing the transformation between three-dimensional space and using the graphic image, are used by supplying the projector (1) for visualization of a two-dimensional image.

13. The method according to claims 8-12, characterized in that when the projector is displaced (1), the displayed graphic image (8) changes often enough to preserve the visual spatial coincidence of the scanned data graphically displayed by the projection and the real surface (12) to which they relate .

14. The method according to claims 8-12, characterized in that it is applied through the device for claims 1-7.