阅读说明：本技术 一种评估点云建模误差的分析方法 (Analysis method for evaluating point cloud modeling error ) 是由 不公告发明人 于 2020-06-01 设计创作，主要内容包括：本发明公开了一种评估点云建模误差的分析方法,其分析步骤如下：步骤一：通过各点云建模软件对点云进行建模；步骤一：通过各点云建模软件对点云进行建模；步骤三：将其中误差占比较大的区间进行再划分,逐级确定点云与格网的各误差区间及其百分占比,采用各级误差占比加权的方式累积误差。该一种评估点云建模误差的分析方法,该评估方法方便实用,同时,使用本方法可以解决了在三维激光扫描技术在工程应用中,点云建模误差无法定量评估的问题,且通过在不同建模软件中点云与格网的多级误差分析,可以一定程度反映出不同建模软件在点云建模时的误差差异,填补了三维激光扫描技术在工程应用中点云建模误差无法定量评估的空白。(The invention discloses an analysis method for evaluating point cloud modeling errors, which comprises the following analysis steps: the method comprises the following steps: modeling the point cloud through each point cloud modeling software; the method comprises the following steps: modeling the point cloud through each point cloud modeling software; step three: and subdividing the interval with larger error, gradually determining each error interval and percentage ratio of the point cloud and the grid, and accumulating the errors by adopting a mode of weighting each error ratio. The analysis method for evaluating the point cloud modeling error is convenient and practical, meanwhile, the problem that the point cloud modeling error cannot be quantitatively evaluated in the engineering application of the three-dimensional laser scanning technology can be solved, the error difference of different modeling software in the point cloud modeling can be reflected to a certain degree through the multi-stage error analysis of point clouds and grid nets in different modeling software, and the blank that the point cloud modeling error cannot be quantitatively evaluated in the engineering application of the three-dimensional laser scanning technology is filled.)

1. An analysis method for evaluating point cloud modeling errors is characterized by comprising the following steps: the analysis steps are as follows:

the method comprises the following steps: modeling the point cloud through each point cloud modeling software;

step two: comparing the established model grid with the point cloud by using the detection function modules of respective software, and analyzing the matching degree of the grid model and the point cloud;

step three: the interval with larger error is subdivided, each error interval and percentage ratio of the point cloud and the grid are determined step by step, and the error is accumulated by adopting a mode of weighting each error ratio;

step four: and multiplying the surface area of the grid by the accumulated error to obtain the upper limit and the lower limit of the point cloud modeling error of the modeling software, so as to obtain the point cloud modeling error.

2. The analytical method for evaluating point cloud modeling error of claim 1, wherein: and determining the point cloud modeling error by weighting and accumulating the errors step by step in a multi-stage matching mode.

3. The analytical method for evaluating point cloud modeling error of claim 1, wherein: the point cloud modeling software in the first step is Geomagic and 3 Dreshaper.

Technical Field

The invention relates to the technical field of surveying and mapping three-dimensional laser scanning, in particular to an analysis method for evaluating point cloud modeling errors.

Background

The three-dimensional laser scanner is widely applied in various fields, the point cloud acquisition and modeling by using the laser scanner are one of important means for restoring and scanning detailed characteristics of an object, and the three-dimensional laser scanner has the advantages of low cost, short period, high precision and the like. However, in practical engineering applications, besides the measurement error existing in the acquisition stage of the point cloud, there is also a modeling error in the point cloud modeling process. The point cloud modeling process generally includes: point cloud filtering and denoising, 3D modeling, feature extraction and the like.

At present, in common point cloud processing software including Geomagic and 3Dreshaper, modeling algorithms are different, and modeling results are different to some extent. Therefore, how to evaluate the error of each software point cloud modeling is significant.

Disclosure of Invention

The invention aims to provide an analysis method for evaluating point cloud modeling errors, so as to solve the problems in the background technology.

In order to achieve the purpose, the invention provides the following technical scheme:

an analysis method for evaluating point cloud modeling errors comprises the following analysis steps:

the method comprises the following steps: modeling the point cloud through each point cloud modeling software;

step two: comparing the established model grid with the point cloud by using the detection function modules of respective software, and analyzing the matching degree of the grid model and the point cloud;

step three: the interval with larger error is subdivided, each error interval and percentage ratio of the point cloud and the grid are determined step by step, and the error is accumulated by adopting a mode of weighting each error ratio;

step four: and multiplying the surface area of the grid by the accumulated error to obtain the upper limit and the lower limit of the point cloud modeling error of the modeling software, so as to obtain the point cloud modeling error.

As a further scheme of the invention: and determining the point cloud modeling error by weighting and accumulating the errors step by step in a multi-stage matching mode.

As a still further scheme of the invention: the point cloud modeling software in the first step is Geomagic and 3 Dreshaper.

Compared with the prior art, the invention has the beneficial effects that:

the invention provides an analysis method for evaluating point cloud modeling errors, which is convenient and practical, and meanwhile, the method can solve the problem that the point cloud modeling errors cannot be quantitatively evaluated in the engineering application of a three-dimensional laser scanning technology, and can reflect the error difference of different modeling software in point cloud modeling to a certain extent through multi-stage error analysis of point clouds and grids in different modeling software, thereby filling the blank that the point cloud modeling errors cannot be quantitatively evaluated in the engineering application of the three-dimensional laser scanning technology.

Drawings

FIG. 1 is a schematic diagram of a model and a relative position of a point cloud for an analysis method for evaluating a point cloud modeling error.

Fig. 2 is a detailed analysis diagram of a point cloud modeling error in an analysis method for evaluating the point cloud modeling error.

Fig. 3 is a diagram illustrating a mesh model and a primary statistical analysis of point cloud errors in 3Dreshaper software in an analysis method for evaluating point cloud modeling errors.

Fig. 4 is a quadratic statistical analysis diagram of a grid model and a point cloud error in 3Dreshaper software in an analysis method for evaluating a point cloud modeling error.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1 to 4, in an embodiment of the present invention, an analysis method for evaluating a point cloud modeling error includes the following analysis steps:

the method comprises the following steps: modeling the point cloud through each point cloud modeling software;

step two: comparing the established model grid with the point cloud by using the detection function modules of respective software, and analyzing the matching degree of the grid model and the point cloud;

step three: the interval with larger error is subdivided, the dividing times are determined according to the precision requirement, each error interval and percentage ratio of the point cloud and the grid are determined step by step, and the error is accumulated by adopting a mode of weighting each error ratio;

step four: and multiplying the surface area of the grid by the accumulated error to obtain the upper limit and the lower limit of the point cloud modeling error of the modeling software, so as to obtain the point cloud modeling error.

And step-by-step weighting and accumulating the errors step by step to determine a point cloud modeling error in a multi-stage matching mode, wherein point cloud modeling software in the step one is Geomagic and 3 Dreshaper.

The working principle of the invention is as follows:

in the point cloud modeling process, due to the difference of filtering and modeling algorithms of modeling software, points floating on the built model or wrapped in the model exist in the point cloud (see fig. 1). p is the point floating above the surface of the model and q is the point wrapped inside the model. d is the distance of the point to the model surface (see fig. 2).

In an ideal case, the weighted error and thus the overall modeling error can be obtained by the distance from each point in the point cloud to the surface of the model to be built, as shown in equation (1-1). Wherein the number of points floating above the surface of the model, the number of points wrapped inside the model, the surface area of the built model, and the modeling error are represented.

However, in practical engineering applications, the number of point clouds is huge, both geogenic and 3Dreshaper consider the factors of calculation efficiency and response time, and the function of matching the grid and the point clouds can only divide the distance from the point clouds to the model into corresponding interval ranges and give weight ratios of the distance ranges, but not the specific distance from each point to the model. Therefore, the formula (1-1) needs to be adjusted appropriately, as shown in the formula (1-2):is the mean value of the interval of the points p floating on the surface of the model,is the average value of the interval where the point q is wrapped in the model, n_Zone(s)、m_Zone(s)Is the corresponding number of intervals.

Experiments show that the matching degree of the grid model and the point cloud can be analyzed through the comparison detection functional module, but the error partition is thick, and a large number of errors are concentrated in a small interval. (see fig. 3), the modeling error proportion in the range of-0.0123 to 0.0212m is 97.77%, the errors are concentrated in a large amount, the span of the error range is 0.0335m and is greater than the preset error range precision threshold value by 0.01m, and therefore the modeling error is large.

A multistage modeling error analysis method is adopted, and the specific method comprises the following steps:

(1) the preliminary analysis results were divided into two parts, as shown in FIG. 3, according to the model surface area (177 m)²) And calculating the volume modeling error of the interval partition except 97.77% to be about-0.12-0.03 m³；

(2) Setting an error elimination range, partitioning an error interval of-0.0123 m to 0.0212m again (see figure 4), concentrating the main error ratio in the interval of-0.00114 to 0.00109 after partitioning again, wherein the ratio is 85.4%, concentrating a large number of errors, the span of the error interval is 0.00223m, and calculating the error interval of which the volume error range is-0.24 to 0.22m when the error interval is smaller than the preset error interval precision threshold of 0.01m³；

(3) Adding the two calculation results to obtain the volume deviation range of-0.36-0.25 m caused by the model volume measurement modeling error³。

Therefore, the influence of the modeling error on the model volume calculation can be accurately determined by the multi-stage modeling error analysis method, and quantitative evaluation basis can be provided for the application focusing on the volume size of the built model body, so that the method has important significance.

Although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes in the embodiments and/or modifications of the invention can be made, and equivalents and modifications of some features of the invention can be made without departing from the spirit and scope of the invention.