A method for detecting geometric changes of 3D murals based on multi-view contour points

Abstract

The invention discloses an automatic detection method for the geometric deformation of the surface of a three-dimensional mural based on the comparison of the contour lines of a laser point cloud by four-dimensional curved surface fitting. First, use the ICP algorithm to roughly register the point cloud data of the two 3D murals, then use the PCA algorithm to obtain the point cloud normal vector, project the normal vector onto the unit Gaussian sphere, and use the multi-view Gaussian sphere parallel projection method to extract the point cloud Finally, the extracted contour lines are compared by the four-dimensional surface fitting method. The invention makes full use of the contour feature information of the point cloud data, and uses the change of the point cloud surface to accurately detect the change of the surface of the three-dimensional mural: the method does not require or only requires very little manual intervention in the entire detection process. It has the characteristics of fast data update, low cost and high precision, and it can also judge the changing nature of the changing area, which provides an effective detection method for the field of cultural relics protection and detection.

Description

technical field [0001] The invention relates to the field of remote sensing science and technology, in particular to the geometric change detection of the surface of a three-dimensional mural by using a three-dimensional laser point cloud (LiDAR), and provides an automatic detection and analysis method. Background technique [0002] The protection and inheritance of cultural relics is of great significance to the development of human society. However, due to the natural environment, human activities, cultural relics and other reasons, cultural relics and historical sites are irreversibly damaged to varying degrees or even disappear in the process of inheritance. Detecting changes in the surface of ancient cultural relics is of great practical significance for the protection and repair of ancient cultural relics. [0003] At this stage, the main methods for detecting the surface changes (shapes) of cultural relics are as follows: (1) Manual surveying and mapping method: usin...

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Problems solved by technology

[0004] Although the above-mentioned methods can be applied to the protection and research of the surface of cultural relics, and an accurate 3D model of cultural relics has been established, these methods do not fully take into account the 3D changes of the surface of cultural relics

The surface of 3D murals is artificially carved and irregular in shape, with dense and irregular features. Whether the existing cultural relic detection methods can be used for the geometric detection of 3D mural surfaces remains to be further confirmed.

In addition, most of the current research on ancient cultural relics based on point clouds uses point cloud data to establish 3D models, and the detection of mural surface changes is mostly focused on two-dimensional change detection research, such as fading, swelling, and pests on the surface of murals. There are few methods for detecting geometric changes on the surface, so there is an urgent need for a method to detect three-dimensional geometric changes on the surface of cultural relics

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