MAT FOR CARRYING OUT A PHOTOGRAMMETRY METHOD, USE OF THE MAT AND ASSOCIATED METHOD

Abstract

A mat for carrying out a photogrammetry method, having an upper side with a scanning surface, on which an object to be captured by means of the photogrammetry method can be placed, wherein a plurality of markers which can preferably be distinguished from one another is arranged on the scanning surface, said markers being detectable when carrying out the photogrammetry method, so as to be used during the creation of a 3D model of the object being captured by means of the photogrammetry method. The invention further specifies the use of the mat for carrying out a photogrammetry method, a computer-implemented method for the photogrammetric creation of a 3D model of an object, and a computer-readable storage medium.

Claims

1. A mat for carrying out a photogrammetry method, having an upper side with a scanning surface, on which an object to be captured by means of the photogrammetry method can be placed, wherein a plurality of markers which can preferably be distinguished from one another is arranged on the scanning surface, said markers being detectable when carrying out the photogrammetry method, so as to be used during the creation of a 3D model of the object being captured by means of the photogrammetry method.

2. The mat according to claim 1, wherein at least one marker has a machine-readable code which is preferably formed by a barcode, matrix barcode, QR code, n-bit circle marker, passer mark and/or frame mark.

3. The mat according to claim 1, wherein the scanning surface is substantially rectangular or substantially circular, preferably substantially square, more preferably square, in particular with an edge length of at least two metres.

4. The mat according to claim 1, wherein the markers are configured and arranged on the scanning surface in such a manner that they can be used to create a bounding box around the object being captured, wherein at least some of the markers are preferably arranged along a first diagonal and a second diagonal of the scanning surface, preferably substantially equidistantly and/or at a fixed distance from one another.

5. The mat according to claim 1, wherein size references are applied to the scanning surface of the mat for scaling and determining the relative positioning of an object to be captured on the scanning surface during the photogrammetry method, which size references are preferably shaped as concentric circles and/or rectangles and/or length markings centred on the midpoint of the scanning surface of the mat along one and/or more of the outer edges of one or more of the concentric rectangles and/or the scanning surface of the mat.

6. The mat according to claim 1, wherein colour references are formed on the scanning surface which allow there to be a white balance and/or a colour adjustment while the photogrammetry method is being carried out.

7. Use of a mat according to claim 1 for carrying out a photogrammetry method.

8. A computer-implemented method for the photogrammetric creation of a 3D model of an object, preferably using a mat according to claim 1, comprising the following steps: placement of an object to be captured on a scanning surface of a mat with markers which are preferably designed to be distinguishable; photographing of the object from a plurality of different directions, in order to create images of the object and at least some of the markers on the scanning surface; scaling of one or more of the images with the help of an adjustment of the captured images, using the markers captured in the images; creation of a 3D model of the object based on the processed images.

9. The method according to claim 8, comprising the creation of a bounding box around the object in the 3D model.

10. The method according to claim 8, comprising the provision of a digital model of the mat, in particular a digital model of the scanning surface of the mat, wherein the digital model of the mat is taken into account during the photogrammetric creation of the 3D model of the object.

11. The method according to claim 8, comprising the implementation of a white balance and/or a colour adjustment of the images with the help of an adjustment of colour references formed on the scanning surface.

12. The method according to claim 8, wherein the placement of the object being captured on the scanning surface of the mat comprises a placement of one or multiple transparent spacers on the mat, on which the object is placed in such a manner that the spacers are arranged between the mat and the object.

13. A computer-readable storage medium which contains instructions that cause the at least one processor to implement the method according to claim 8, when the instructions are carried out by the at least one processor.

Description

[0046] In the drawing

[0047] FIG. 1 shows a plan view of the mat according to an exemplary embodiment of the invention.

[0048] FIG. 2 shows a schematic perspective view of an exemplary embodiment of the mat with an object placed thereupon, in which a bounding box is depicted.

[0049] FIG. 3 shows a perspective view of the mat according to an exemplary embodiment of the invention with the object situated thereupon.

[0050] FIG. 4 shows a perspective view of the mat according to an exemplary embodiment of the invention with an object which is arranged on the spacers.

[0051] The figures are only schematic in nature and are used simply for understanding the invention. The same kinds of elements are provided with the same reference signs in the description of the exemplary embodiments.

[0052] FIG. 1 shows a plan view of the mat M according to an exemplary embodiment of the invention. The mat M in this exemplary embodiment has a substantially quadratic shape. On its surface, the mat M has a scanning surface S which takes up the entire upper side of the mat M in the present exemplary embodiment. The scanning surface S has a plurality of markers 11, which have circular 12-bit markers in the present exemplary embodiment and are distributed over the scanning surface of the mat. The markers 11 have no rotational symmetry, which makes it easier to identify the orientation of the mat. Furthermore, the scanning surface S has multiple concentric size references 16 in the form of concentric rectangles, and coloured labels 13 and concentric circles 12, which are used as size and positional references. Further measures 16a which make it easier to identify sizes when implementing a photogrammetry method using the mat M are located along the rectangular size references.

[0053] Along the outer edges of the mat M are located rulers 14 which likewise provide a size ruler. In the present exemplary embodiment, the rulers 14 are designed as length scales. In addition, colour markings 15 which allow a subsequent colour adjustment or white balance are distributed over the scanning surface S. Furthermore, angle markings 18 are printed through the midpoint 19 of the scanning surface S, which are at a known angle to one another. This makes it easier for relative or absolute angular relationships to be determined when images of an object O are taken from different angles. Also shown is an overprint with a guide 17 for the user. In addition, directional arrows 20 are formed on the scanning surface S, which indicate the orientation of the mat M as a whole. The directional arrows 20 may also be applied to the size references 12 or to other size references (not shown), in order to provide an orientation guide.

[0054] The mat M is provided for use in a photogrammetric method. In this case, an object O, of which a 3D model is to be created by means of photogrammetry, is placed on the scanning surface S of the mat M. The placement preferably takes place in such a manner that the object O is placed as centrally as possible on the scanning surface S. It is thereby ensured that the largest possible area of the scanning surface S is visible from all viewing directions. The object O placed on the scanning surface S is then photographed from a plurality of different directions. In this way, images of the object O are created, on which at least some of the markers 11 are visible on the scanning surface S of the mat M. The images create a scan of the object O. Further reference variables of the scanning surface, such as the size references 12, 16, the rulers 14, 16a, the colour markings 15, the angle markings 18 and/or the directional arrows 20, can preferably be seen in at least some of the images. The images taken from different directions or perspectives are then scaled in relation to one another. For scaling, the markers 11 of the scanning surface S are used in the images. In addition, at least some of the reference features of the scanning surface S, in other words the size references 12, 16, the rulers 14, 16a, the colour markings 15, the angle markings 18 and/or the directional arrows 20, are preferably used to scale and/or adjust the images in respect of one another. Based on the images scaled and/or adjusted in respect of one another, a 3D model of the object O can then be created by means of photogrammetry.

[0055] FIG. 2 shows a perspective view of a mat M according to a further exemplary embodiment of the invention, on which an object O is placed. Also drawn in is a bounding box 21, which makes it possible for a 3D model of the object O to be demarcated against the background in a scan. The bounding box 21 in this case can be determined taking account of, for example, the cover of the different markers 11 in the images of a scan. The creation of the bounding box 21 in this case can preferably be taken over automatically by photogrammetry software. The bounding box 21 around the object O may, however, also be created manually by the user in one or multiple images. The closer to the object O the bounding box 21 is defined in this case in the plurality of images taken, the more efficient the subsequent compilation of the images into a model. In particular, an accurate determination of the bounding box 21 also reduces the work involved in the manual reworking of the images which may be necessary.

[0056] FIG. 3 shows a perspective view of a mat M on which an object O is placed, according to a further exemplary embodiment. An object O which is to be captured by means of photogrammetry is arranged on the scanning surface S. With the help of the concealed, or partially concealed, markers 11, the outlines of the object O can be accurately captured. With the help of the size references 16, or 12, a subsequent scaling of the images within the scan in relation to one another is possible with a substantially reduced amount of work. The directional arrows 20, optionally along with the angle markings 18, can thereby be used to determine the perspective from which images of the scan are taken.

[0057] When performing the method according to the invention, in particular when using the mat M according to the invention, the creation of a 3D model from a plurality of images taken from different perspectives is made substantially easier. The printed guide 17 can preferably provide specifications on the angles from which, or the angle intervals in which, images are to be taken according to the corresponding markings 20 and 18. The mat M according to the exemplary embodiments explained above allows a substantial increase in the accuracy of a 3D model which is to be created. The quality of the 3D model produced depends crucially on the number of identified, common features in different images. Due to inaccuracies, the number of generated 3D points is frequently only a very small fraction of pixels or camera pixels. Due to the provision of the mat M with the features described, an environment for a photogrammetry method can be created without substantial expenditure, which supplies a plurality of different absolute references on account of the features of the mat M, which references can be used in implementing the photogrammetry method, in order to significantly improve the adjustment of the images to one another and therefore the accuracy of the 3D model created.

[0058] FIG. 4 shows the perspective view of a mat M according to a further exemplary embodiment, on which an object O is placed on spacers 22. The preferably non-slip design of the scanning surface S in this case makes for easier placement of the object O. The object O in this case is partly, or completely, arranged on the spacers 22. The placement of the object on the scanning surface S of the mat M with the spacers 22 interposed also makes it easier for the object to be photographed from a plurality of different directions. In particular, photographs of the underside, or part of the underside of the object O, can thereby also be achieved. The three-dimensional resolution of the 3D model of the object O is thereby improved when the images are compiled into a model. The transparency of the spacers 22 means that they can easily be distinguished from the object O itself, which is advantageous both for the subsequent processing of the images and also for the separation of the spacers 22 from the 3D model of the object O.

[0059] LIST OF REFERENCE SIGNS

[0060] M mat

[0061] S scanning surface

[0062] O object

[0063] B image

[0064] 11 marker

[0065] 12, 16 size references

[0066] 14, 16a ruler

[0067] 15 colour markings

[0068] 17 guide for users

[0069] 18 angle markings

[0070] 19 midpoint of the scanning area

[0071] 20 directional arrows

[0072] 21 bounding box

[0073] 22 spacer