WO2019086498A1

WO2019086498A1 - Method for creating a total image for determining depth of an object

Info

Publication number: WO2019086498A1
Application number: PCT/EP2018/079782
Authority: WO
Inventors: Thomas Engel
Original assignee: Siemens Aktiengesellschaft
Priority date: 2017-11-06
Filing date: 2018-10-31
Publication date: 2019-05-09
Also published as: DE102017219660A1

Abstract

A method for creating a total image for determining depth of an object is proposed, which method comprises at least the following steps: – projecting a plurality of marking elements onto at least one part of the surface of the object by means of at least one projection device; – detecting a first individual image of a first partial region of the surface of the object; – detecting a second individual image of a second partial region of the surface of the object, wherein the second partial region at least partly overlaps the first partial region; and – joining together the first and second individual images to form the total image, wherein during the joining together process, the projected marking elements detected in the first and second individual images are used at least partly as reference. Furthermore, the invention relates to a method for determining depth of an object, in particular of a symmetrical object.

Description

description

A process for the preparation of an overall image for a Tie ^¬ fenbestimmung an object

The invention relates to a method for creating an overall image for a depth determination of an object, in particular ^{¬ a} special component. Furthermore, the invention relates to a method for depth determination of the object by means of an optical triangulation method using the Gesamtabbi1des.

For optical triangulation of comparatively large objects or components, measuring systems with a likewise large detection range are required. Thus, for example, fringe projection systems are known from the prior art, which have a detection range of about 2 x 2.5 m ² . However, the measuring field of such measuring systems is limited. It may therefore be necessary to combine several individual images into a complete image (English: stitching). Furthermore, the joining of individual images to an overall image can be referred to as stitching. In particular, in the stitching method, a measurement of the object can be made from different spatial directions. Afterwards, it is necessary to merge or correlate the captured individual images.

, The object to be measured or component few charac teristic ^¬ features and / or symmetry, such known methods may fail to joining of the individual images according to the prior art. In other words, the individual images are assembled incorrectly, so Artefak ^¬ te occur in single images created by the overall image. This is therefore the case since it can thus lead to incorrect Resul ^¬ did, for example, by the high symmetry of the object to be measured to Mehrdeu ^¬ ACTIVITIES of assembly and. An attempt is made to improve the joining of the individual images by means of physical marking elements arranged on the object (also called markers). However, this results in the disadvantage that areas of the object are obscured by the physical marking elements arranged on the object.

The aforementioned physical marking elements can likewise be used in the case of optical triangulation of the object as a reference for joining the individual images acquired in this case. Are, however, also results here the disadvantage is that, for example, an intended for optical triangulation pattern distorted by said marking elements or is influenced and / or Berei- surface of the object by said marking elements completely covered and not achieved by the pattern for Tiefenbe ^¬ humor ,

Alternatively, a symmetrical object can be measured on a turntable. An attempt is made by means of the rotation of the turntable Stel ^¬ lung remove the ambiguity resulting from the symmetry of the object, and thus to the single images ^¬ piece together to allow possible without artifacts.

The object of the present invention is to provide an overall image, in particular for large and / or symmetrical objects, which improves a depth determination of the object.

The object is achieved by a method having the features of independent claim 1 and by a method having the features of independent claim 7. In the dependent claims advantageous refinements and developments of the invention are given. The inventive method for creating a Gesamtab ^¬ image for a depth determination of an object, in particular a component, comprises at least the following steps:

- projection of a plurality of marking elements on GR nigstens part of the surface of the object by means we ^¬ nigstens a projection apparatus;

- Detecting a first single image of a first Teilbe ^¬ rich of the surface of the object;

- acquiring a second image of a second single-rich Teilbe- the surface of the object, wherein the second Teilbe partially overlaps ^¬ reaching at least to the first portion; and

- Assembling the first and second individual images to the overall image, wherein the assembled in the first and second single image captured projected marking elements are used at least partially as a reference.

First of all, it should be made clear that the projected marking elements are not used for the actual depth determination of the object. In other words, the projected markers in the sense of the present invention of an optical pattern which is projected onto the surface of the object and to the optical Triangula ^¬ tion, that is intended for depth determination, differ to un-. However, the projected marking elements may be simultaneously projected with the optical pattern intended for depth determination, for example a stripe pattern. In this sense, the projected marking elements are to be understood as auxiliary marks, which are used as a reference when combining the individual images. However, the projected marker elements may be used to improve recognition and / or evaluation of the pattern intended for depth determination. In particular, defects and / or other defects in the pattern provided for depth determination can be improved by the projected marking elements. According to the present invention are advantageously the marking elements which are used when joining the single-entity ^¬ images as a reference, projected on the surface be ^¬ relationship as to at least a part of the surface of the object. This advantageously - in contrast to the object physically arranged marking elements - no areas of the object covered by the projizier ^¬ th marking elements. In particular, this is advantageous for objects which have few characteristic features and / or high symmetry. By means of proji ^¬ ed markers can likewise be advantageously used for sol ^¬ che objects an almost unique joining of the individual images. In other words, according to the present invention, the stitching of the individual images to the overall image takes place by means of marking elements that have been projected onto the surface of the object. Here, the markers are in relation to understand the depth determination of the object involved as auxiliary members, which is only used when ^¬ to piece together the individual images. For example, the marking elements are used as a reference for resolu ^¬ sen a symmetry of the object. As a result, reduced demands on the orientation of the marking elements on the surface of the object can be made, since in particular only the symmetry should be canceled or broken by means of the projected marking elements.

In particular, it is not necessary that the projected markers remain in terms of whether ^¬ ject or its surface rigid or fixed. However, it is advantageous if the projected marking elements are arranged at least over the time range of the measurement with respect to the object almost or sufficiently stationary on its surface. Thereby, characteristics of the OBJEK ^¬ tes, for example, holes or flanges which are disposed symmetrically typical ^¬ on the object, when Zusammenfü- gene of the individual images, that is the stitching process, are recognized.

In particular, it is advantageous if the majority of the projected ed marker elements form a pattern Markie ^¬ approximately in its entirety, which has no ambiguity, that is, which is unique. For this purpose, the pattern formed by the totality of the marking elements is preferably formed by means of random or stochastically arranged points (English: random dot pattern). The resulting random distribution of the projected marking elements on the surface of the object ambiguities are almost completely avoided. Another advantage of the projected markers that those opposed to physical Markierungsele ^¬ elements need not be arranged manually on the object. This can be saved advantageously work ^¬ the. Furthermore, it is not necessary to remove the projected marking elements after depth determination of the object. As a result, in particular for critical components, the risk of overlooking physical marking elements and leaving them on the object can be avoided. As a result, the reliability of the object is significantly improved. Beispiels- example could be an electric breakdown caused by a forget ^¬ nes physical marker in an active part ei ^¬ nes transformer. The same can not happen with projected marking elements. In an advantageous embodiment of the invention, the projected marking elements are projected onto the surface of the object such that their arrangement causes at least one symmetry of the object to be broken. In other words, the markers are used as Refe ^¬ ence to resolve a symmetry of the object. As a result, errors and / or artifacts when merging the individual images, which are due to the sym- Metrics of the object could arise, avoided. This is the case because, due to the breaking of the symmetry, an almost unambiguous assignment of further features, for example characteristic features of the object, can take place in the individual images. In this sense, that is to break the symmetry, the marking elements in combination ^¬ add the individual images are used as a reference.

According to an advantageous embodiment of the invention, at least one physical marking element is arranged on the object and used when assembling the individual images as a further reference.

In addition to the projected marking elements an additional physical Mar ^¬ kierungselement to the object can be placed upstream in part by way of at least legally. A multi ^¬ number of arranged on the object physical marking elements may be provided. It is particularly preferred if the physical marking ^¬ element is arranged in such a way on the object that it lichst mög ^¬ slightly obscured by the object. In particular, an advantageous arrangement of the physical marking elements can be provided in holes, for example boreholes, or within a flange. Advantageously, the assembly of the individual images is improved by the at least one physical marking ^element . Furthermore, it may be provided that is arranged at least one physical marker ^¬ element by means of a magnet to a magnetic object. In particular, the physical Markie ^¬ approximately element, for example, screws or Gewindelö ^¬ cher, be designed as a nut or bolt. Furthermore, the physical marking element can be formed almost flat or as a three-dimensional structure, in which case information about the orientation or pose of the object can be obtained by means of its geometry, that is to say its three-dimensional structure. In an advantageous embodiment of the invention, the projection device is arranged stationary relative to the object and / or connected to this non-positively and releasably.

Advantageously, the projection device is arranged stationarily with respect to the object to be measured. As a result, the spatial position of the projected marking ^{elements is} substantially stable with respect to the object. An arrangement of the projection device on the object, that is, for example, that the projection device is ^{kraftschlüs ¬} sig and releasably connected thereto, is particularly advantageous if the object moves during the measurement or depth determination. As a result, the relative position between the projection device and the object, even with a movement of the object, is maintained. By the fixed arrangement of the projection device relative to the object, in particular highly symmetric OBJEK ^¬ te or components can be made accessible without the characteristic features of a Stit- ching method according to the present invention.

According to an advantageous embodiment of the invention, four projection devices are used.

As a result, a sufficient number of projected marking elements is advantageously projected onto the object, as a result of which its spatial orientation, which is reflected in the recorded individual images, can be recognized almost unambiguously during the joining of the individual images. If necessary, as two, three or five projek ^¬ tion devices beneficial. In particular, it is advantageous to arrange all projection devices used stationary and detachable on the object. When using a plurality of projection devices, it is advantageous to couple them and to coordinate with each other. Here, the vote in relation to the projected marking elements may be such that no Ambiguous ^¬ opportunities arise. In particular, the projection devices are controlled in such a way and / or coordinated with each other that it is uniquely possible to decide which projection device the respective projected marking elements originated from.

According to an advantageous development of the invention, characteristic features of the object and / or arranged on the object physical markers that are detected on the zelabbildern ^¬ A, used in the joining of the individual images as a further reference.

In particular, a two-stage stitching method is thereby formed.

In a first, coarse stage by means of the projected marking elements, a pre-alignment of the Einzelabbil ^¬ the. In this case, the goal is that the symmetry of the object is essentially resolved and / or broken and / or detected by means of the projected marking ^elements . This information can then be taken into account in the stitching process. In this sense, the projected marking elements are used here as a reference.

The actual stitching process takes place in a second, finer stage by means of the characteristic features of the object and / or the physical marking elements and in the above-mentioned sense (resolution of the symmetry of the object) likewise by means of the projected marking elements. Overall, this advantageously improves the joining of the individual images to the overall image. In the inventive method for depth determination of an object, the depth determination of the object with ^¬ means of an optical triangulation method is performed. The OF INVENTION ^¬-making process according to the depth determination of the object is characterized in that from detected in the optical Triangula ^¬ tion process Einzelabbildern a total image of the present invention or any of its embodiments, is created, and the total image is used for depth determination of the object.

In other words, the total image, which is used for depths ^¬ determination of the object is created by means of a ^¬ he inventive stitching process. This results in the already mentioned inventive method for creating an overall image for a Tiefenbe ^¬ mood of the object similar and equivalent Vortei ^¬ le. In particular, it is advantageous in this case if a phase shift method is used as the optical triangulation method.

According to an advantageous embodiment of the invention, a symmetry of the object is determined by means of at least projizier ^¬ th marking elements and the determined Symmet ^¬ rie taken into account when assembling the first and second individual image. Advantageously, the symmetry of the object can thus already be taken into account when assembling the individual images to the overall image, so that the depth determination of the object can be improved. Under the symmetry determining the breaking of the symmetry of the object can also be understood by the projected Markie ^¬ guide elements. In other words, the projected marking elements are arranged on the surface of the object such that at least one symmetry of the object is broken by their arrangement. In this case, the said arrangement is not to be understood physically, since the projected marking elements are projected onto the surface.

If the symmetry of the object broken by the projected Markie ^¬ guide elements or known, the of the joining of the individual images by means of characteristic features of the object can be performed. In this sense, that is to dissolve or break the symmetry of the object, the proji ^¬ ed marking elements are used in the assembly of the single-entity ^¬ images.

In an advantageous embodiment of the invention, a camera with a dynamic range greater than or equal to 100 decibels (dB) is used to capture the individual images. Particular, it is advantageous to use the camera in a Lin / log mode for improved detection of Markie ^¬ guide elements. Advantageously, thereby the projected marking elements above the Intensi ^¬ tätsbereiches an intended for depth determination pattern, in particular a stripe pattern arranged ^¬ the. Characterized can be made an improved separation of the projected markers and vorgese ^¬ Henen for depth determination pattern. Alternatively or in addition, a high dynamic range (English: High Dynamic Range abbreviated HDR) are achieved by means of a multi ^¬ multiple exposure with a camera with a smaller dynamic range. In particular, there is provided the projected marking ^¬ elements as well as the projected for depth determination Mus ^¬ ter can simultaneously on the surface of the object to projizie ^¬ ren. Furthermore error within the projected and for the depth determination provided pattern by the projected marking elements, if they are well separated from each other, be recognized and improved. This is in particular ^¬ sondere the case when the pro- jizierte for depth determination pattern is a stripe pattern and the projected marking elements formed point-like or punctiform.

Alternatively or additionally, the pattern provided for the depth tuning can be combined with the marking elements, whereby uniqueness can likewise be produced.

Further advantages, features and details of the invention ^¬ give themselves playing from the exemplary embodiments described below and with reference to the single drawing. The single figure shows a flow chart of the method according to the invention.

In a first step S1 of the method according to the invention for producing an overall image for a depth determination of an object, a projection of a plurality of marking elements onto at least one part of the surface of the object takes place by means of at least one projection device. In a second step S2, a first individual image ei ^¬ nes first portion of the surface of the object is detected.

In a third step S3, a second individual image ei ^¬ nes second sub-area of the surface of the object is detected, wherein the second sub-area overlaps at least partially with the first sub-area.

In a fourth step S4 of the method according to the invention, the detected first and second individual images are combined to form a total image, wherein when assembling the acquired in the first and second individual image projected marking elements at least partially USAGE ^¬ det as a reference (stitching method). Although the invention has been further illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples, or other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims

claims

1. A method for creating an overall image for a depth determination of an object, comprising the steps:

- Projection of a plurality of marking elements on at least a part of the surface of the object by means of we ^¬ least one projection device;

- acquiring a second image of a second single Teilbe ^¬ rich the surface of the object, wherein the second Teilbe partially overlaps ^¬ reaching at least to the first portion; and

- joining the first and second individual images samtabbild to Ge, wherein the detected in the first and th two ^¬ single image projected marking elements are at least partially used as a reference during assembly.

2. The method according to claim 1, wherein the projected Mar- kierungselemente be such jiziert that a symmetry of the object is refracted by their arrangement, at least on the surface of the object per ^¬.

3. The method according to claim 1 or 2, wherein at least one physical marking element is arranged on the object and used in assembling the individual images as a further reference.

4. The method according to any one of the preceding claims, wherein the projection device is arranged stationary with respect to the object and / or connected to this non-positively and releasably.

5. The method according to any one of the preceding claims, in which four projection devices are used.

6. The method according to any one of the preceding claims, wherein the characteristic features of the object and / or body 2 0 1 7 2 2 2 7

WO 2019/086498 PCT / EP2018 / 079782

14 lie on the object arranged marking elements that are recognized on the individual images, are used when joining the individual images as another reference.

7. A method for depth determination of an object, wherein the depth of the object is determined by means of an optical triangulation method, characterized in that from the individual images recorded in the optical triangulation method, an overall image according to one of claims 1 to 6 is created, and that the overall image for depth determination of Object is used.

8. The method according to claim 7, wherein the optical Triangu ^¬ lationsverfahren a phase shift method is used.

9. The method according to claim 7 or 8, wherein at least one symmetry of the object is determined by means of the projected marking ^¬ elements, and the determined symmetry is taken into account when joining the first and second individual image.

10. The method according to any one of claims 7 to 9, wherein the camera is used with a dynamic range greater than or equal to 100 decibels capturing the individual images.

11. The method according to any one of claims 7 to 10, wherein the projected marking elements are projected onto the surface of the object, that we ^¬ least one symmetry of the object is broken by their arrangement.