# US 11,443,418 B2 · Machine vision system with a computer generated virtual reference object

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 11,443,418 B2
- Document ID: US11443418B2
- Status: Granted
- Kind: B2
- Application number: 16/772,914
- Filed: 2018-12-14
- Published: 2020-10-01
- Granted: 2022-09-13
- Earliest claimed: 2017-12-15
- Assignees: Mapvision Oy Ltd.
- Applicants: Oy Mapvision Ltd
- Inventors: Esa Leikas
- Web page: https://patentgrep.com/patent/US11443418B2

## CPC

- G01B 11/24: for measuring contours or curvatures
- G06T 7/0006: {using a design-rule based approach}
- G06T 7/001: {using an image reference approach}
- G06T 7/60: Analysis of geometric attributes
- G06T 7/97: {Determining parameters from multiple pictures (depth or shape recovery from multiple images G06T7/55; stereo camera calibration G06T7/85)}
- G06T 2207/10012: Stereo images
- G01B: MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL

## Abstract

A machine vision system using a computer generated virtual reference object is disclosed. When the exact measures of the virtual reference object are known the machine vision system is capable of measuring differences on an absolute scale. In the machine vision system, a virtual reference object is produced based on computer drawings. The computer generated virtual reference object is further processed in order to achieve high photorealistic accuracy. The processing may involve combining portions from image of a manufactured object or computationally producing an image that looks like measured object. When the computer generated virtual reference object is based on the model drawing it does not include inaccuracies caused by manufacturing tolerances.

## Claims

### Claim 1

A method for measuring an object comprising:
receiving a three-dimensional computer generated virtual reference object, wherein the received virtual reference object is generated based on a model drawing of the object and the virtual reference object comprises exact coordinates of the object, wherein the exact coordinates comprise coordinates of at least one discrete point;
acquiring at least two images of the object, wherein the acquired at least two images are acquired with at least two different cameras;
determining a three-dimensional location of at least one discrete point on the object based on the acquired images, wherein the determined three-dimensional location is in the same coordinate system with the three-dimensional computer generated virtual reference object;
determining the corresponding discrete point coordinates on the virtual reference object; and
based on the determined location of at least one discrete point on the acquired images and corresponding exact coordinates on the virtual reference object,
computing the absolute scale location of at least one discrete point on the object.

### Claim 2 (depends on 1)

A method according to claim 1, wherein the method further comprises generating the computer generated virtual reference object based on the model drawing of the object.

### Claim 3 (depends on 2)

A method according to claim 2, wherein the generating further comprises receiving additional information comprising at least one of the following: lighting setting information, object material information, object color information or camera parameters.

### Claim 4 (depends on 3)

A method according to claim 3, wherein the camera parameters comprise camera coordinates and camera orientation.

### Claim 5 (depends on 2)

A method according to claim 2, wherein the generating further comprises:
acquiring at least one image of a manufactured object;
generating a projection view based the model drawing, wherein the projection view corresponds with the direction of acquiring at least one image of a manufactured object; and
aligning at least portion of acquired at least one image on the generated projection view.

### Claim 6 (depends on 2)

A method according to claim 2, wherein the generating further comprises producing a photorealistic image of the object based on the model drawing and received additional information.

### Claim 7 (depends on 1)

A computer program embodied on a non-transitory computer-readable medium, said computer program comprising one or more instructions which, when executed by a computing device, carry out method according to claim 1.

### Claim 8 (depends on 1)

A controller comprising at least one processor and at least one memory, wherein the at least one processor is configured to perform a method according to claim 1.

### Claim 9 (depends on 1)

A machine vision system comprising:
a housing;
a camera system comprising a plurality of cameras inside the housing;
a lighting system comprising a plurality of lighting devices inside the housing; and
a controller, wherein the controller is configured to perform a method according to claim 1.