3D Measuring Apparatus Boundary Position Accuracy

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Solution Overview

Problem

Conventional methods for determining the boundary position between light and dark portions in spatial coding for three-dimensional measurement are inaccurate and time-consuming, particularly due to blur and reflectance issues, leading to errors in measuring the three-dimensional shape of objects.

Innovation Solution

A measuring apparatus and method that uses a combination of binary coded light patterns and their reversed versions, along with a calculation processing unit to determine the boundary position by analyzing luminance values and intersections, reducing the number of required patterns and improving accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional methods are used to determine boundary position between light and dark portions, then measurement can be performed, but accuracy is poor due to blur and reflectance issues

Engineering Contradiction:
Improveboundary position accuracyVSAvoidmeasurement method complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent applies inversion by projecting both the original stripe light pattern and its reversed pattern (where light and dark portions are swapped) onto the object. By comparing the captured images of both patterns, the boundary position can be determined more accurately because the reversal compensates for blur and reflectance issues that affect single-pattern measurements.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The patent changes the pattern parameter by using multiple stripe light patterns with different spatial coding configurations. Instead of relying on a single pattern, the system projects several patterns and processes their combined information to determine boundary positions, thereby improving measurement accuracy while managing complexity through systematic parameter variation.

Inventive Principle:
Principle #35Parameter changes

2Measurement precision

If more stripe light patterns are projected to improve boundary position accuracy, then measurement precision improves, but measurement time increases

Engineering Contradiction:
Improveboundary position accuracyVSAvoidmeasurement time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent uses periodic action by projecting stripe light patterns in a systematic sequence - original pattern, then reversed pattern - and capturing images at regular intervals. This periodic projection approach allows the system to gather sufficient data for accurate boundary determination while maintaining a predictable and efficient measurement rhythm that minimizes total measurement time.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The patent applies preliminary action by first projecting the original stripe light pattern and capturing its image, then immediately projecting the reversed pattern. This preliminary sequencing of pattern projections allows the measurement system to efficiently process both patterns in a predetermined order, optimizing the balance between accuracy and measurement time.

Inventive Principle:
Principle #10Preliminary action

3Extent of automation

If binary coded stripe light pattern is used, then spatial coding can be performed, but boundary position determination becomes inaccurate due to blur

Engineering Contradiction:
Improvespatial coding capabilityVSAvoidboundary position accuracy
Core Design Contradiction:
Extent of automationVSMeasurement precision

Solution Approach 1:

The patent resolves the blur issue in binary coded spatial coding by introducing the reversed stripe light pattern. The reversal creates a complementary view where boundaries that are blurred in one direction become clearer when viewed from the reversed pattern, allowing accurate boundary position determination even when using automated binary coded spatial coding methods.

Inventive Principle:
Principle #13The other way round (Inversion)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The method allows for accurate and quick determination of the boundary position, matching the precision of complementary pattern projection methods while reducing the number of patterns needed, thus enhancing measurement efficiency and accuracy in three-dimensional shape measurement.

Implementation Method 1

a pattern projection method has been known in which an object, onto which patterned light is projected several times, is captured to measure a shape of the object

Methodology Applied
Scientific EffectLight: Light

Implementation Method 2

a camera 131 for capturing a reflected pattern

Methodology Applied
Scientific EffectReflection: Reflection

Data Source

PatentEP2459960B1Measuring apparatus, measuring method, and computer program
Publication Date: 2019.11.13 CANON KK
  • EP2459960B1 patent drawingFigure 1
  • EP2459960B1 patent drawingFigure 2
  • EP2459960B1 patent drawingFigure 3A

AI summary

A measuring apparatus includes a projection control unit configured to cause a projection unit to project, onto an object, a first light pattern with light and dark portions, a second light pattern, which is smaller in distance between the light and dark portions than that of the first light pattern and has a boundary position between the light and dark portions common to the first light pattern, and a third light pattern in which the light and dark portions of the second light pattern are reversed to each other, an acquisition unit configured to acquire a first captured image of the object onto which the first light pattern is projected, a second captured image of the object onto which the second light pattern is projected, and a third captured image of the object onto which the third light pattern is projected, and a calculation unit configured to calculate the boundary position between the light and dark portions of the first captured image based on the second and the third captured image to measure the position of the object.