Point Cloud Filtering Using Pre-computed Quality Metrics

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Solution Overview

Problem

Existing methods for creating point cloud representations from raw data, such as digital surface models and orthophotos, often require multiple iterations to achieve satisfactory detail and resolution, as the initial selection of points based on quality information may not meet user expectations, leading to inefficiencies and unnecessary recalculations.

Innovation Solution

A method that filters point clouds using user-provided selection criteria related to quality information, including variance and number of images used for position calculation, allowing for optimized representation without altering the volume or substance of the original point cloud, enabling users to iteratively refine the display until desired density and noise levels are achieved.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a new point cloud is generated from raw data with adjusted quality thresholds to improve model detail, then the quality of displayed digital model is improved, but the time and computational resources required increase significantly

Engineering Contradiction:
Improvequality of displayed digital modelVSAvoidtime for generating point cloud
Core Design Contradiction:
Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent pre-calculates and stores quality information for each point in the point cloud during the initial generation phase. This includes computing variance values and image count metrics for all points beforehand, so that subsequent filtering operations can quickly select points based on user-defined thresholds without re-processing the entire raw data set. This preliminary preparation eliminates the need to regenerate the entire point cloud when adjusting quality parameters.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent separates the point cloud data into individual point records, each containing coordinate information and pre-computed quality attributes. This segmentation allows the system to filter and select specific points based on quality criteria without processing the entire point cloud, enabling efficient adjustment of model detail by selecting only the necessary points rather than regenerating the complete data set.

Inventive Principle:
Principle #1Segmentation

2Manufacturing precision

If multiple iterations of point cloud generation are performed with different quality thresholds, then the desired level of detail is achieved, but the productivity and efficiency of the workflow deteriorate

Engineering Contradiction:
Improvelevel of detail in digital modelVSAvoidefficiency of finding satisfactory surface model
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The system performs all necessary quality calculations during the initial point cloud generation, storing variance and image count information for each point. This preliminary computation enables multiple filtering iterations with different quality thresholds to be performed rapidly on the already-processed data, eliminating the need to re-generate the point cloud for each iteration and thus maintaining high productivity while achieving the desired level of detail.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements an interactive filtering process where users can review the filtered point cloud representation and adjust quality thresholds based on the displayed results. The system provides feedback by showing the effect of different filtering criteria, allowing users to iteratively refine the selection of points until the desired model quality is achieved, all without regenerating the underlying point cloud data.

Inventive Principle:
Principle #23Feedback

3Measurement precision

If the predefined range of quality information is changed to improve point selection, then the accuracy of point cloud is improved, but the complexity of the process increases

Engineering Contradiction:
Improveaccuracy of point cloudVSAvoidcomplexity of point cloud generation process
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent pre-computes and stores multiple quality metrics for each point, including variance values and image count information. This preliminary preparation of quality data simplifies the subsequent filtering process, as users only need to specify threshold values without needing to understand or configure complex processing parameters. The system handles the complexity of quality assessment automatically during the initial processing phase.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent enables users to adjust quality thresholds by changing simple parameter values (such as minimum variance or minimum image count) rather than modifying complex processing algorithms. This parameter-based approach allows users to improve point cloud accuracy by adjusting straightforward quality criteria without increasing process complexity, as the underlying computation framework remains unchanged.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS11106937B2Method for creating point cloud representations
Publication Date: 2021.08.31 LEICA GEOSYSTEMS AG
  • US11106937B2 patent drawing

AI summary

A method for creating point cloud representations for a point cloud generated based on images, wherein the method comprises receiving a point cloud generated based on images, retrieving, from a user, selection criterion information, wherein the selection criterion information is related to the quality information comprised by the points of the point cloud, and filtering the generated point cloud and creating a filtered-point-cloud representation to be displayed while leaving volume and substance of the generated point cloud unchanged, wherein for each point of the point cloud its quality information is compared with the retrieved selection criterion information and only those points of the point cloud are used for the creation of the filtered-point-cloud representation to be displayed, which have a quality information fulfilling the retrieved selection criterion information, and displaying the filtered-point-cloud representation to the user.