KR102220237B1 - 3D Modularization and Method of CT Image Information for the Restoration of Cultural Heritage - Google Patents

Abstract

The present invention provides a method for accurately modeling a three-dimensional shape of a metal cultural property, and for performing a 3D modeling by taking a CT image of an object to be photographed and removing noise outside and inside the data of the captured CT image information. In addition, the present invention is to provide an accurate shape inside a cultural property that cannot be seen with the naked eye through removal of noise due to light reflection peculiar to a metallic cultural property through a filter and a histogram method in the process of extracting image information through CT imaging.
In the 3D modular method of CT image information for preservation and restoration of cultural assets according to the present invention, a CT image obtained by continuously photographing a cultural asset as an object to be photographed, and information about a 3D image from the CT image are extracted, and from the CT image information Image data and resolution data are separated and stored, and then a binarized image is extracted by removing noise from the image data, and an outline of a cross section of the shape of the object to be photographed is extracted.
Extracting point data of an outline from the extracted outline, filling the inside of the extracted outline to remove internal noise, removing noise information of the extracted outline, and reconstructing the 3D shape of the object from the point data will be.

Description

3D Modularization and Method of CT Image Information for the Restoration of Cultural Heritage}

The present invention relates to 3D modulating of CT image information for preserving and restoring cultural properties, and to a method thereof. Specifically, using software to secure the visibility of the result through the extraction of image information and 3D modulating through CT imaging. It clarifies the boundaries of the results and relates to methods for preserving and restoring cultural properties based on the results.

In the conventional CT imaging apparatus and CT imaging method, a threshold of a CT value is set for each voxel, and each voxel is classified by a dichotomy based on the predetermined threshold. That is, when the subject to be photographed is divided into "voxels", which correspond to the smallest unit recognizable in X-ray CT, some voxels are made up of only one medium, but voxels described as mixels. In the case of, it is not purely composed of one medium, but the other medium is mixed. That is, in the mixer, various types of media are mixed with a predetermined volume ratio.

However, in the conventional CT imaging apparatus and CT imaging method, since voxels are classified by a dichotomy based on a predetermined threshold, it is simply determined whether the CT value for each voxel exceeds the threshold. In other words, each voxel is simply classified into one of two as black and white. In the prior art, even if there is a mixel in which various types of media are mixed, voxels are classified into only two types based only on the threshold value of the CT value without considering the volume ratio of the media mixed in the mixel at all. As described above, the conventional X-ray CT imaging apparatus and X-ray CT imaging method do not consider the volume ratio of the medium in the mixel at all. Therefore, when the volume ratio of the medium constituting the imaging target is calculated, accuracy and reliability are low. There are technical limitations.

Korean Patent No. 10-1120250 discloses a method of processing an image obtained by performing X-ray CT in the medical field, and Korean Patent No. 10-1370496 discloses a complex medium using X-ray CT. Disclosed is a method of processing an image obtained by performing the volume of each pure medium in a photographing object consisting of.

In an X-ray CT imaging apparatus, an X-ray is transmitted through an object to be photographed to form a three-dimensional image of the object to be photographed in a voxel unit, which is a three-dimensional image unit. In other words, in the image of the object obtained by 3D X-ray CT, the "voxel" made of a three-dimensional cube becomes the minimum basic unit, and the object having a three-dimensional shape is formed by gathering basic units of a three-dimensional image called voxels. can do. In this specification, the process of calculating a CT value for each voxel forming a three-dimensional object through X-ray is abbreviated as "CT photographing" for convenience, and the 3D X-ray CT imaging device used at this time is for convenience. It is abbreviated as "CT imaging device".

As the consciousness of the people grows, the number of visits to cultural heritage sites distributed in various places and the preparation of Korean history required for examination life in recent public periods, as the demand for seeing cultural assets in person has increased. There is a movement to preserve and permanently preserve cultural assets by preserving and restoring unsuccessful cultural assets or cultural assets that have already been exhibited and attracting public attention.

In general, the degree of rust and corrosion of the internal structure through CT photographing in consideration of the characteristics of making it difficult to grasp the degree of internal corrosion and the degree of abrasion of the finishing material, and the rust or corrosion occurring inside the part where it is difficult to know It has been reported in articles such as the Cultural Heritage Administration to understand and clarify the maintenance of cultural properties.

As a conventional technology, it is described in relation to the method of measuring anisotropy of materials using 3D X-RAY CT imaging described in No. 10-0141889. In the part of taking an image through X-RAY imaging, the invention content of the present invention Although there are parts similar to those described through the anisotropic beam and the absence of work to clarify the boundary line using the Laplacian filter, the technical content of the present invention was proposed.

Since commonly used X-ray or CT scans provide limited information in two dimensions, it is difficult to accurately determine a shape in a three-dimensional space.

Since commonly used X-ray or CT imaging provides limited information in two dimensions, it is difficult to accurately determine a shape in a three-dimensional space.

Korean Patent Publication No. 10-0141889 (2015. 12. 21)

The present invention provides a method for accurately modeling a three-dimensional shape of a metal cultural property, and for performing a 3D modeling by taking a CT image of an object to be photographed and removing noise outside and inside the data of the captured CT image information.

In addition, the present invention is to provide whether or not rust and cracks are generated inside a cultural property through a filter and histogram method in the process of extracting image information through CT imaging.

In addition, the present invention is to provide a clear boundary line by extracting a boundary line by applying a Laplacian filter to a result obtained based on CT imaging.

In addition, the present invention is to obtain an image from which noise has been removed based on a binarized image in which the PEAK value of the histogram and the surrounding values are matched using a Laplacian filter.

In order to achieve the above object, the 3D modulating method of CT image information for preservation and restoration of cultural assets according to the present invention is a CT image continuously photographed of a cultural asset as a photographing object, and information on a 3D image is extracted from the CT image. Then, image data and resolution data are separated and stored from the CT image information, and then a binarized image is extracted by removing noise from the image data, and an outline of a cross section of the shape of the object to be photographed is extracted.

Extracting point data of an outline from the extracted outline, filling the inside of the extracted outline to remove internal noise, removing noise information of the extracted outline, and reconstructing a three-dimensional shape of the object from the point data. .

In order to extract the binarized image, noise is removed by setting two boundary values of black and white, and boundary value 1 takes the middle value of 2 regions, and boundary value 2 starts at the histogram value 255 in regions 3 and 4 until peak 2. The 3D shape of the object is reconstructed by determining the starting point at which the slope of the curve of is 120.

The method of removing internal noise is to fill the inside of the object, but to fill the inside, each pixel is examined in eight directions to distinguish the inside and the outside, and the inside pixel gradually expands and finally the inside Is completely filled.

The present invention uses a method of 3D modeling from CT images for preservation and restoration of cultural assets made of metal, and in this way, it is possible to accurately reproduce and restore the shape and internal appearance of cultural assets. That is, X-ray or CT scan information that provides only 2D information makes it difficult to accurately determine a 3D shape, but this problem can be solved accurately.

The present invention provides an accurate three-dimensional shape by removing data surface and internal noise generated by 3D data conversion, thereby enabling 3D modeling using CT image information of a metal cultural property.

1 is a separate CT image information stored in a raw format file of the present invention.
2 is a histogram of CT image information according to the present invention.
3 is a binary image obtained by processing a CT image of a subject in the present invention.
4 is an outline showing the internal noise of the binary image according to the present invention.
5 is a diagram showing a data processing process for removing noise according to the present invention.
6 is an outline image extracted while noise is removed according to the present invention.
7 is a result of extracting points of an outline image according to the present invention.
8 is a 3D modulating result using outline image information from which noise is removed according to the present invention.

The present invention relates to 3D modulating and method of CT image information for preservation and restoration of cultural properties. The boundary line is made clear using a Laplacian filter, and the histogram area is divided and the boundary value is set to adjust pixels to remove the noise of the boundary value. The binary image with one boundary value is extracted and 3D modeled.

As the consciousness of the people increases in recent years, the number of visits to cultural heritage sites distributed in various places and the preparation of Korean history required for examination life in recent public periods have increased the demand for seeing cultural assets in person. A movement to preserve cultural assets permanently by preserving and restoring unsuccessful cultural assets or those that have already been exhibited and attracting public attention has emerged.

In general, the degree of rust and corrosion of the internal structure through CT photographing in consideration of the characteristics of making it difficult to grasp the degree of internal corrosion and the degree of abrasion of the finishing material, and the rust or corrosion occurring inside the part where it is difficult to know It has been reported in articles such as the Cultural Heritage Administration to understand and clarify the maintenance of cultural properties.

The present invention in which noise is removed from a CT image and outline information is extracted and 3D modulated will be described in detail using the drawings below.

1 is a separate CT image information stored in a raw format file of the present invention, FIG. 2 is a histogram of CT image information of the present invention, and FIG. 3 is a binary image processed by a CT image of a subject in the present invention. And Figure 4 is an outline showing the internal noise of the binary image of the present invention is included, Figure 5 is a diagram showing the data processing process for noise removal of the present invention, Figure 6 is extracted from the noise of the present invention This is an outline image. FIG. 7 is a result of extracting points from an outline image of the present invention, and FIG. 8 is a result of 3D modulating using the outline image information from which noise is removed.

In order to implement a 3D shape, information on a 3D shape must be extracted from a continuous CT image of an object to be photographed, such as a cultural property cast out of metal. The first step is to separate and store image and resolution information from CT data, and the second step is to extract the outline of the cross section of the shape from the image separated from the CT data using image processing technology. The final step is to reconstruct a 3D shape in a virtual space using computer graphics technology from the point data obtained from the image processing result.

FIG. 1 relates to conversion of CT data. When a CT photograph of an object to be photographed, such as a cultural property, various measurement information in addition to image information is mixed with the CT data. Image information and other information are separated from such CT data and only image information is stored.

The separated image information of FIG. 1 is stored as a raw format file having a resolution of 512x512 pixels, and information other than the image information is stored as a text file. Among the information stored in the text file, numerical information on the actual measurement is included, and is used as a measurement standard in the process of reconstructing the 3D shape.

2 is a histogram of CT image information of an object of the present invention. Each continuous CT image contains 2D information on the cross section of the object to be photographed. The 3D shape is reconstructed by removing unnecessary components from the 2D information, extracting the cross-sectional information of the object to be photographed, and placing it in a virtual space continuously. In order to perform such 3D modular work, the image segmentation technique and the Laplacian filter are used to detect the outline required for the 3D shape of the captured CT image.

To do this, first, a process of processing image data to remove noise from a 3D image must be performed. That is, unnecessary noise components must be removed in order to detect the outline of the object to be photographed. The CT image of FIG. 1 has a histogram as shown in FIG. 3 and only the pixel resolution value is changed. When the histogram area is separated and displayed, area 1 is a dark area other than the object to be photographed, area 2 is a boundary area with the outside, and area 3 is an area substantially containing image information of the object to be photographed. When you enlarge the 3 area, there are two peaks in the histogram, and these two peaks represent the boundary between the object to be photographed and other data. Area 4 is an area that does not contain any information. The boundary value of the entire image segmentation is not constant according to the change of resolution in each CT image. Therefore, in order to solve this problem, different boundary values are determined and used according to each area of the histogram of FIG. 2.

That is, as shown in FIG. 2, noise is removed from image information by setting and applying two boundary values. Boundary value 1 takes an intermediate value of region 2 of FIG. 2, and boundary value 2 determines a starting point at which the slope of the curve from the histogram 255 to peak 2 in regions 3 and 4 is 120. The slope of 120 is a value obtained through a threshold experiment using 65 CT images. Boundary value 1 is a value of an area that separates the boundary from an area other than the object to be photographed, and the image processing result of applying the two boundary values is shown as a binary image as shown in FIG. 3. 3 is a binary image obtained by processing a CT image of a subject in the present invention.

In FIGS. 4 to 7, a data processing procedure for removing internal noise of a binarized image will be described. 4 is an outline showing the internal noise of the binarized image of the present invention, and FIG. 5 is a diagram showing a data processing process for removing noise of the present invention, and FIG. 6 is an outline extracted from the noise-removed state of the present invention. Image, and FIG. 7 is a result of extracting points of the outline image according to the present invention.

A clear 3D image can be obtained only by removing noise from the binarized image and detecting a clear outline. For this 3D modularity, a Laplacian filter was used for edge detection. The Laplacian filter has the advantage of extracting an outline consisting of one pixel from a binarized image, but when applied to an image resulting from an image segmentation, the outline for internal noise also appears as shown in FIG. 4.

Therefore, in order to extract the outline of the binarized image, the internal noise must be first removed before applying the Laplacian filter. Since internal noise also appears as the same component as the outline, it cannot be removed simply by image segmentation.

In order to remove the internal noise, it is preferable to fill the inside of the object to be photographed. In order to fill the interior, in this technology, the surrounding pixels are examined in eight directions for each pixel to distinguish the interior and the exterior, and the interior pixels are gradually expanded to finally completely fill the interior.

In addition, it is difficult to completely remove the noise generated by reflection peculiar to metal. Therefore, it is necessary to manually selectively remove the metallic light reflection pixels represented in the CT image in order to extract the perfect outline data.

5 shows this process, and finally shows the result of extracting the desired outline while the internal noise is completely removed.

FIG. 8 is a 3D modulating result completed through the above process, using the outline image information from which noise has been removed, and 3D modulating by removing internal noise.

Claims (3)

In the 3D modular method of CT image information for preservation and restoration of cultural properties,
The 3D modulating method extracts information on a 3D image from a CT image obtained by continuously photographing a cultural property as an object to be photographed, and the CT image,
After separating and storing image data and resolution data from the CT image information, an outline of a cross section of the shape of the object to be photographed is extracted from the image data, and noise is removed to extract a binarized image to extract the outline,
In order to extract the binarized image, noise is removed by setting the boundary values of black and white (border value 1, boundary value 2), boundary value 1 takes the middle value of 2 areas, and boundary value 2 is 3 areas and 4 areas. Reconstruct the 3D shape of the object to be photographed by taking the starting point at which the slope of the curve from the histogram 255 to the first peak (peak 2) is 120,
Extracting point data of an outline from the extracted outline, removing noise inside the extracted outline, removing noise information of the extracted outline, and reconstructing a three-dimensional shape of the object to be photographed from the point data. 3D modulating method of CT image information.

delete The method of claim 1,
The method of removing internal noise is to fill the inside of the object, but to fill the inside, each pixel is examined in eight directions to distinguish the inside and the outside, and the inside pixel gradually expands and finally the inside A 3D modular method of CT image information, characterized in that the three-dimensional shape of the object to be photographed is reconstructed by completely filling.

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