US-20260127733-A1 - METHOD, DEVICE AND SYSTEM FOR DETECTING A SHAPE DEVIATION

US20260127733A1US 20260127733 A1US20260127733 A1US 20260127733A1US-20260127733-A1

Abstract

In order to recognize a shape deviation of an inspection object from a three-dimensional target geometry in three dimensions, three-dimensional, back-projections onto the three-dimensional target geometry are determined by at least one processing circuit, wherein a back-projection onto at least a part of the three-dimensional target geometry is determined for each of several two-dimensional images of the inspection object. The back-projections determined for the several two-dimensional images are compared by the at least one processing circuit in order to recognize the shape deviation.

Inventors

Matthias Karl
Jan Henrik Fitschen

Assignees

CARL ZEISS AG

Dates

Publication Date: 20260507
Application Date: 20251219
Priority Date: 20230623

Claims (15)

1 . A method for recognizing a shape deviation of an inspection object from a three-dimensional target geometry in three dimensions, the method comprising: receiving two-dimensional images of the inspection object by at least one processing circuit; determining several back-projections onto the three-dimensional target geometry by the at least one processing circuit, wherein a back-projection onto at least a part of the three-dimensional target geometry is determined for each of several of the two-dimensional images of the inspection object; and, comparing the several back-projections determined for the several of the two-dimensional images via the at least one processing circuit in order to recognize the shape deviation.
2 . The method of claim 1 , wherein said comparing the several back-projections is carried out for each of several different facets of the three-dimensional target geometry.
3 . The method of claim 1 , wherein, on a basis of said comparing the several back-projections, the at least one processing circuit performs a spatially resolved ascertainment of regions in which an outer envelope of the inspection object deviates from an outer envelope of the three-dimensional target geometry.
4 . The method of claim 1 , further comprising providing an output on a basis of the recognized shape deviation.
5 . The method of claim 4 , wherein the output comprises a spatially resolved visualization of the recognized shape deviation.
6 . The method of claim 1 , wherein the several back-projections are determined on the basis of poses of an image capture device when capturing the two-dimensional images, wherein the method further comprises ascertaining the poses via the at least one processing circuit.
7 . The method of claim 6 , wherein said ascertaining the poses is achieved via at least one of: one of the two-dimensional images, the three-dimensional target geometry and camera parameters of the image capture device used to capture the one of the two-dimensional images; and, sensor data assigned to the one of the two-dimensional images.
8 . The method of claim 1 further comprising: reading three-dimensional target geometry data from a memory system; and, creating a scaled model of an outer envelope of the three-dimensional target geometry on a basis of the read three-dimensional target geometry data by the at least one processing circuit, wherein the several back-projections are determined on a basis of the scaled model of the outer envelope.
9 . The method of claim 1 further comprising selecting the several of the two-dimensional images from the received two-dimensional images by the at least one processing circuit.
10 . The method of claim 1 further comprising: receiving additional two-dimensional images by the at least one processing circuit; and, comparing further back-projections onto the three-dimensional target geometry determined from the additional two-dimensional images in order to improve the recognition of the shape deviation.
11 . The method of claim 1 further comprising creating control data or control signals by the at least one processing circuit for a purpose of controlling or guiding a capture of the two-dimensional images, wherein the at least one processing circuit uses the three-dimensional target geometry for the creation of the control data or control signals.
12 . The method of claim 1 , wherein the recognized shape deviation is caused by a faulty manufacturing process for the inspection object, by a deformation of the inspection object post manufacturing or by a foreign body that has remained on the inspection object.
13 . A machine-readable command code for recognizing a shape deviation of an inspection object from a three-dimensional target geometry in three dimensions, the machine-readable code being stored on a non-transitory computer readable medium, the machine-readable code comprising machine-readable instructions that, upon execution by at least one processing circuit, prompt the at least one processing circuit to: receive two-dimensional images of the inspection object by at least one processing circuit; determine several back-projections onto the three-dimensional target geometry by the at least one processing circuit, wherein a back-projection onto at least a part of the three-dimensional target geometry is determined for each of several of the two-dimensional images of the inspection object; and, compare the several back-projections determined for the several of the two-dimensional images via the at least one processing circuit in order to recognize the shape deviation.
14 . An apparatus or system for recognizing a shape deviation of an inspection object from a three-dimensional target geometry in three dimensions, the apparatus comprising: at least one processing circuit configured to: determine a respective back-projection onto at least a part of the three-dimensional target geometry for several two-dimensional images of the inspection object; and, undertake a comparison of the back-projections determined for the several of the two-dimensional images in order to recognize the shape deviation.
15 . The apparatus or system of claim 14 , further comprising: an image capture device for capturing the several two-dimensional images.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation application of international patent application PCT/EP2024/067017, filed June 19, 2024, designating the United States and claiming priority from German application 102023116 637.9, filed June 23, 2023, and the entire content of both applications is incorporated herein by reference. TECHNICAL FIELD The disclosure relates to methods, apparatuses and systems for recognizing a shape deviation using electromagnetic radiation. In particular, the disclosure relates to methods, apparatuses and systems for image-based recognition of a deviation between a three-dimensional geometry of an inspection object and its three-dimensional target geometry. BACKGROUND Recognizing a shape deviation between an actual three-dimensional (3-D) geometry of an inspection object and its 3-D target geometry has various fields of application, for example in quality control. Recognizing a shape deviation using electromagnetic radiation and optical techniques in particular is attractive for various reasons, for example on account of the attainable speed and on account of its contactless manner of operation. For example, a deviation between target and actual geometries may be effected by the determination of the actual geometry. Methods using structured illumination allow the determination of the actual geometry but require well-defined illumination patterns and knowledge about the illumination patterns. A surface may be measured with great accuracy using the techniques disclosed in EP 2321614 B1, but a light source that usually cannot be handled manually is required to this end. DE 102020134680 A1 discloses a quality control method, in which images may be captured using a mobile capture device and subsequently be evaluated. However, the application of this quality control technique may entail comparatively large outlay as regards the configuration for the quality control to be performed, for instance the definition of a reference point and the definition of the target geometry. In order to obtain detailed information at the component level during this inspection, it is necessary for the target geometry to be available in such a format that individual components may be removed and/or addressed on an individual basis. However, this requirement is not met in some fields of application. The result of the inspection may be subjected to undesirably strong influences, for example as a result of the texture of the inspection object. Thus, the technology still needs improved methods, apparatuses and systems for recognizing a shape deviation. SUMMARY It is an object of the disclosure to provide improved methods, apparatuses and systems for recognizing a shape deviation. In particular, a problem addressed is that of specifying such methods, apparatuses and systems that may be operated with little setup complexity and can be used for various object geometries. In this context, it is optionally desirable to provide methods, apparatuses and systems in which necessary data acquisition on the inspection object may be carried out in a simple manner. The above object is achieved via various embodiments of the disclosure. According to an aspect, the disclosure relates to a method for recognizing a shape deviation of an inspection object from a 3-D target geometry of the inspection object in three dimensions (3-D). The method includes: receiving two-dimensional, 2-D, images of the inspection object by at least one processing circuit, determining several back-projections onto the 3-D target geometry by the at least one processing circuit, wherein a back-projection onto at least a part of the 3-D target geometry is determined for each of several 2-D images of the inspection object, and using the at least one processing circuit to perform a comparison of the back-projections determined for the several 2-D images in order to recognize the shape deviation. Various technical effects and advantages are obtained by the method. The method is based on the use of several 2-D images in combination with the 3-D target geometry. This allows the recognition of inconsistencies that indicate a deviation from the 3-D target geometry. In this context, there is no need to reconstruct the actual geometry of an inspection object in 3-D in order to detect deviations from the 3-D target geometry. Instead, the back-projections of at least two and advantageously more than two 2-D images onto the 3-D target geometry are used in order to recognize both the presence and the location of a shape deviation between the actual geometry and the 3-D target geometry of the inspection object. A technical advantage of the method consists in the latter operating on the basis of 2-D images that may be captured using a conventional camera, for example a camera integrated in a mobile device. A further technical advantage lies in the fact that structured illumination is not required. Hence, staff without special training may al