Occluded Edge Detection in 3D Point Clouds

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Solution Overview

Problem

Existing methods for constructing computer models of complex structures from 3D point data are time-consuming and error-prone, especially when dealing with occluded edges or irregular shapes, due to issues with point density, noise, and the need for manual segmentation and scaling.

Innovation Solution

A system that allows users to select a seed point along an occluded edge and automatically generates an initial edge profile, which can be adjusted, using algorithms like RANSAC for robust fitting and moving window termination detection to handle varying point density and noise, enabling the modeling of continuous edges even with sparse data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If manual segmentation and scaling steps are used to remove spurious points, then manufacturing precision of edge modeling is improved, but loss of time increases significantly

Engineering Contradiction:
Improveedge modeling precisionVSAvoidmodeling time
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent applies preliminary action by performing automatic segmentation and filtering operations before the edge fitting process. The system pre-identifies and removes spurious points from the point cloud data, and pre-segments the data into relevant regions, so that when the edge fitting algorithm runs, it works with cleaned, pre-processed data rather than requiring manual intervention to remove errors.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements self-service through automated algorithms that perform segmentation, filtering, and edge detection without user intervention. The computer automatically identifies spurious points, segments the point cloud into meaningful regions, and fits edges to the data, replacing the need for manual segmentation and scaling steps that users would otherwise have to perform.

Inventive Principle:
Principle #25Self-service

2Ease of operation

If step-wise approach is used to locate edges, then ease of operation is improved, but manufacturing precision deteriorates due to overshooting or undershooting edge ends

Engineering Contradiction:
Improveedge location simplicityVSAvoidedge endpoint accuracy
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The patent transitions from step-wise 2D representation methods to direct 3D point cloud processing. By working in the full three-dimensional space rather than projecting to 2D views, the system can accurately locate edge endpoints and follow irregular shapes without the dimensional limitations that cause overshooting or undershooting in traditional step-wise approaches.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The system replaces manual mechanical operations (user interaction to rotate views, draw shapes, and adjust selections) with automated computational algorithms. The computer automatically processes the 3D point data, identifies edge features, and fits geometric models without requiring users to manually manipulate views or draw reference shapes, thereby eliminating the precision errors associated with step-wise manual methods.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If full data density is used in point-by-point methods, then measurement precision is improved, but use of energy and computational resources increases unnecessarily

Engineering Contradiction:
Improveedge detection precisionVSAvoidcomputational energy consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent applies segmentation by dividing the point cloud data into distinct regions or groups before processing. Instead of analyzing every single point individually at full density, the system segments the data into meaningful clusters or zones, allowing it to process representative samples from each segment rather than all points, thereby reducing computational energy while maintaining edge detection precision.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system uses partial action by processing only the necessary portion of the data at full density. Rather than applying full data density processing uniformly across the entire point cloud, the system identifies and processes only the relevant regions containing edge information at high precision, while using lighter processing for other areas, thus reducing overall computational energy consumption.

Inventive Principle:
Principle #16Partial or excessive action

Data Source

PatentUS7843448B2Identification of occluded edge regions from 3D point data
Publication Date: 2010.11.30 LEICA GEOSYSTEMS AG
  • US7843448B2 patent drawing
  • US7843448B2 patent drawing
  • US7843448B2 patent drawing

AI summary

An improved interface and algorithm(s) can be used to simplify and improve the process for locating an occluded edge from a series of points in a point cloud. An interface can allow the user to select a hint point thought to be near an edge of interest, which can be used to generate an initial edge profile. An interface can allow the user to adjust the fit of the initial profile in cross-section, then can use that profile to generate a profile of the entire edge. A moving fit window can use an imaginary plane to provide an additional constraint, and can utilize a moving average to extend the edge and determine proper end locations. An interface then can display the results of the fit to the user and allow the user to adjust the fit, such as by adjusting the end points of the calculated edge. Such a process can be used to fit linear or curvilinear occluded edges, and can fit a number of irregular shapes as well as regular shaped edges such as “v-shaped” edges.