KR101666449B1 - Apparatus for reverse engineering sweeping shape using feature template similarity based on 3 dimentional point cloud and method thereof - Google Patents

Abstract

Disclosed are an apparatus and a method for reverse engineering a sweeping shape by using shape template similarity based on three-dimensional (3-D) point cloud. According to the present invention, the apparatus for reverse engineering the sweeping shape by using the shape template similarity includes: a segmentation unit for segmenting given 3-D point cloud data (PCD) to obtain a plurality of PCD segments; a skeleton extracting unit for extracting each path of the obtained PCD segments; a segmentation section extracting unit for extracting a section over each branch of the extracted paths; a similarity calculating unit for comparing similarity between the obtained section and predefined shape templates to select a cross-sectional shape template on a basis of a result of the comparison; and a sweeping unit for automatically generating a sweeping shape by using the selected cross-sectional shape template.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for reversely designing a sweeping shape using a three-dimensional point cloud based shape template similarity,

The present invention relates to a three-dimensional swept shape reverse design technique, and more particularly, to an apparatus and method for reverse designing a sweep shape using a three-dimensional point cloud-based shape template similarity.

The reverse design technology is a technology for extracting the 3D shape from the facility and modeling the object attribute information for purposes such as facility maintenance and construction. Reverse engineering technology is a key technology for facilities / energy maintenance / operation, modular construction, and facility reconstruction. Reverse engineering technology is used not only in the maintenance market, but also in prefabrication, construction inspection, plant facilities, bridges and tunnel structures. It is also used for 3D printing technology, to be.

When extracting a shape from a PCD, there are various problems such as errors caused by surveying, partial omission due to invisible area, noise, etc. in a device such as Light Detection And Ranging (LiDAR), and incomplete PCD data In most cases, the pipe is extracted only in a cylinder shape semi-automatically from the 3D model, and the post-processing is manually modeled.

Recently, the reverse design part which is applied in the field of architecture is mechanical, electrical, and plumbing (MEP) which is complicated in shape and has many design changes. In recent years, the cost of construction and management of MEP facilities has been steadily increasing due to the characteristics of buildings requiring high performance. MEPs have many sweeping shapes that can be modeled using sections and paths. To automate this sweeping contour design, you can extract the points and center points of the PCD section, curve fitting, connecting the center points to extract the 3D sweeping shape, or if you specify the section and PCD segments, A semi-automatic reverse design technique has been commercialized and utilized.

These schemes must be fully PCD ready and only support primitive shapes such as pipes, ducts, and trays with fixed cross-sectional dimensions, and do not allow the user to continuously create a three-dimensional sweeping geometry with the desired parameters. If it is not a primitive shape, the user must define the dimension correctly in the section sketch. Therefore, in this case, it is difficult to reverse design the sweeping shape with varying cross-sections.

Accordingly, an object of the present invention is to extract feature points from cross-sectional points extracted from PCD, compare the extracted feature features with predefined shape templates, The present invention also provides an apparatus and method for reverse designing a sweeping shape using a three-dimensional point cloud-based shape template similarity in which a sweeping shape is generated using a template section obtained by acquiring a similar template section.

However, the objects of the present invention are not limited to those mentioned above, and other objects not mentioned can be clearly understood by those skilled in the art from the following description.

In order to achieve the above objects, an apparatus for reverse designing a sweeping shape according to an aspect of the present invention includes: a segmenting unit for segmenting a given PCD to obtain a plurality of PCD segments; A skeleton extracting unit for extracting a center path of each of the obtained plurality of PCD segments; A segmentation section extracting section for extracting a section for each point of the extracted center path; A similarity calculation unit for comparing the obtained similarity of the section with the predefined shape templates and selecting a sectional shape template as a result of the comparison; And a sweeping unit that automatically generates a sweeping shape using the selected cross-sectional shape template.

Preferably, the segmentation unit classifies the given PCD according to a preset reference, and obtains a plurality of PCD segments as a result of classification.

Preferably, the skeleton extractor extracts a center path of each of the plurality of PCD segments using an L1-medial condition-based skeleton extraction technique.

Preferably, the similarity calculation unit calculates a degree of similarity between the acquired section and predefined shape templates, and selects one shape template determined to be most similar to the calculated result as the cross-sectional shape template .

Preferably, the sweeping unit is adapted to fit the selected cross-sectional shape template to the segment, sweep the fitted cross-sectional shape template on the basis of the extracted center path, and generate a sweeping shape as a result of the sweeping.

According to another aspect of the present invention, there is provided a method for reverse designing a sweeping shape, comprising: segmenting a given PCD to obtain a plurality of PCD segments; A skeleton extracting step of extracting a center path of each of the obtained plurality of PCD segments; A segmentation section extracting step of extracting a section for each point of the extracted center path; A similarity calculation step of comparing the obtained similarity of the section with the predefined shape templates and selecting a sectional shape template as a result of the comparison; And a sweeping step of automatically generating a sweeping shape using the selected cross-sectional shape template.

Preferably, the segmentation step classifies the given PCD according to a preset reference, and obtains a plurality of PCD segments as a result of classification.

Preferably, the skeleton extraction step extracts a center path of each of the plurality of PCD segments using an L1-medial condition-based skeleton extraction technique.

Preferably, the similarity calculation unit calculates a degree of similarity between the acquired section and predefined shape templates, and selects one shape template determined to be most similar to the calculated result as the cross-sectional shape template .

Preferably, the sweeping step is characterized by fitting the selected cross-sectional shape template to a segment, sweeping the fitted cross-sectional shape template on the basis of a previously extracted center path, and sweeping the swept shape as a result of the sweeping .

Accordingly, the present invention extracts shape features from the single-sided points extracted from the PCD, compares the extracted shape features with the similarity of predefined shape templates, obtains the most similar template section as a result of the comparison, So that reverse design automation can be performed even in the case of an incomplete PCD.

Further, since the template section is fitted to the sweeping shape modeling, it is not necessary to define the exact dimensions of the section sketch even when the template is not a primitive shape.

1 is a diagram illustrating an apparatus for inverse designing a sweeping shape according to an embodiment of the present invention.
2 is a diagram for explaining a principle of extracting a section according to an embodiment of the present invention.
3 is an exemplary diagram of a template described in XML format in accordance with an embodiment of the present invention.
4 is a view for explaining the principle of FT pattern extraction according to an embodiment of the present invention.
5 is a diagram illustrating a method for inversely designing a sweeping shape according to an embodiment of the present invention.

Hereinafter, an apparatus and method for reverse designing a sweeping shape using a three-dimensional point cloud-based shape template similarity according to an embodiment of the present invention will be described with reference to the accompanying drawings. The present invention will be described in detail with reference to the portions necessary for understanding the operation and operation according to the present invention.

In describing the constituent elements of the present invention, the same reference numerals may be given to constituent elements having the same name, and the same reference numerals may be given thereto even though they are different from each other. However, even in such a case, it does not mean that the corresponding component has different functions according to the embodiment, or does not mean that the different components have the same function. It should be judged based on the description of each component in the example.

Particularly, in the present invention, shape features are extracted from the cross-sectional points extracted from the 3D point cloud data (PCD), and the similarity between the extracted feature features and predefined shape templates is compared, and the most similar template cross- We propose a new method to generate the sweeping shape using the obtained template section.

1 is a diagram illustrating an apparatus for inverse designing a sweeping shape according to an embodiment of the present invention.

1, an apparatus for inversely designing a sweeping shape according to the present invention includes a segmentation unit 110, a skeleton extraction unit 120, a segment section extraction unit 130, a similarity calculation unit 140, (150).

The segmenting unit 110 may classify a given PCD according to a segmentation, that is, a specific criterion, and obtain a plurality of PCD segments as a result of classification.

For example, the segmentation unit 110 acquires a PCD segment from a given PCD using a surface growing smoothness constraint-based region growing technique.

At this time, the number of segments can be adjusted, which is adjusted using the following equation (1).

Here, n _p represents the normal vector of the point p = (p _x , p _y , p _z ) of the PCD, n _s represents the angle between the normal line of the current point and the surrounding point, and? Th represents the allowable angle.

That is, the segmentation is repeated until there is no point p satisfying the above-mentioned expression (1).

The skeleton extractor 120 may extract a skeleton or a center path of each of the plurality of acquired PCD segments. For example, the skeleton extractor 120 extracts a skeleton of the PCD segment using an L1-medial condition-based skeleton extraction technique capable of robust and accurate extraction to noise.

At this time, L1-medial defines [Equation 2] to find x with a given PCD and a minimum distance.

Here, I is a point set x index, J is a Q-set index, ∥∥ is a corrosion function and has a corrosion value according to the difference value of x and Q set, and R (X) It is a function that computes the repulsion force that shrinks to the local center and is no longer shrunk.

At this time, we use the branch-to-branch distance and the direction of the branch end edge to acquire the abbreviated set x in the local center as one branch and to merge the adjacent branches. The acquired branch can be used as a sweeping path.

The segment section extraction unit 130 can extract a section for each point of the extracted skeleton.

2 is a diagram for explaining a principle of extracting a section according to an embodiment of the present invention.

Referring to FIG. 2, at a point P _E to be extracted from the skeleton, a point P _sec is extracted by a thickness T _{sec of the} section (210). And, S _plane for projection (projection) of 3D points in a two-dimensional point on the path and the plane S perpendicular to the _plane. by projecting the obtained after the _affine transformation matrix (220), P _sec in the plane 230, and obtains the two-dimensional set of points P _proj (240).

The segment section extraction unit 130 extracts a section, that is, P _proj , which is a set of two-dimensional points, for each point.

The similarity calculation unit 140 compares the obtained section with the similarity of predefined shape templates, and selects the most similar shape template as a cross-sectional shape template as the comparison result.

At this time, the template including the sectional shape characteristic and the constraint is defined as the following [Table 1].

division Contents FTS = {FT, ...} FTS is a set of FTs FT = {FT _name , FT _tolerance , FT _pattern } FT consists of name, tolerance, sectional shape pattern FT _tolerance = {T _length or T _angle or T _radius } Tolerances are defined for length, angle, and radius. FT _pattern = {FT _element , ...} Patterns consist of pattern elements FT _element = {Dim or Base or Geometry} Pattern elements consist of dimensions, bases, and geometric elements Dim = {D _name , D _values } Dimensions consist of dimension name and dimension values D _values = {values, ...} Dimension values are a set of dimension values Base = {E _name , P _x , P _y } The criterion is a set of element names and coordinate values x, y Geometry = {G _type , G _constraints , G _dim } Geometry elements are defined as geometry types, constraints, and dimensions G _type = {Line or Arc or Last} A geometry type is one of a line, arc, or final geometry type. G _constraint = {On or Tangent} Constraints are attached, or tangential angles G _dim = {L or a or R} The dimensions of the geometric elements are length, angle, radius

The FTS defined above can be described in XML format, as shown in [Table 2] and FIG. 3 below.

<FTS name = 'Structural'>
<FT name = 'H-beam' Tol-L = 0.1 Tol-A = 1.0>
Dim.L: [10.0, 12.0, 13.0, 14.0, 15.0, 16.0, 17.0, 18.0, 19.0, 20.0]
Dim.T: [1.0, 1.5, 2.0, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5]
Base 1: On (0.0, 0.0)
Base 2: On (0.0, -1.0)
Line: On (Base1), Tangent (Base2.P, Base1.P), L (Dim.L)
Line: On (Last), Tangent (Last, 90.0), L (Dim.T)
Line: On (Last), Tangent (Last, 90.0), L (Dim.L - Dim.T / 2)
Line: On (Last), Tangent (Last, -90.0), L (Dim.L-Dim.T * 2)
Line: On (Last), Tangent (Last, -90.0), L (Dim.L - Dim.T / 2)
Line: On (Last), Tangent (Last, 90.0), L (Dim.T)
Line: On (Last), Tangent (Last, 90.0), L (Dim.L)
Line: On (Last), Tangent (Last, 90.0), L (Dim.T)
Line: On (Last), Tangent (Last, 90.0), L (Dim.L - Dim.T / 2)
Line: On (Last), Tangent (Last, -90.0), L (Dim.L-Dim.T * 2)
Line: On (Last), Tangent (Last, -90.0), L (Dim.L - Dim.T / 2)
Line: On (Last), On (Base1.P)
</ FT>
L = 0.1 Tol-R = 0.1 Tol-A = 1.0 < RTI ID = 0.0 &
Base 1: On (0.0, 0.0)
Base 2: On (1.0, 0.0)
Arc: On (Base1.P), Tangent (Base2.P, Base1.P), R (1.0), A (180.0)
Line: On (Last), Tangent (Last), L (7.0)
Arc: On (Last), Tangent (Last), R (1.0), A (180.0)
Line: On (Last), On (Base1.P)
</ FT>
</ FTS>

4 is a view for explaining the principle of FT pattern extraction according to an embodiment of the present invention.

Referring to FIG. 4, it is necessary to simplify (310) P _proj in order to effectively process the comparison between the FT and P _proj defined above. That is, after extracting Polyline P _pline from P _proj , applying the Ramer-Douglas-Peucker algorithm (RDP), and obtaining a simplified P _smooth as a result of the application (320).

From the obtained P _smooth , S _type is extracted by using curve fitting, and P _FTS is generated using the extracted S _type (330). The generated P _{FT- S} is compared with the S _type pattern order defined in the predefined FT (340), and the matching FT _candidates are obtained (350) according to the comparison result.

In this case, the degree of similarity can be defined as the ratio of the length of the FT _{fitting and} the length of the P _{smooth fitting} by the S _type described in the FT _candidate , which is defined as the following Equation (3).

The closest FT to 1.0 is chosen as the cross-sectional shape template that best represents FT _smooth .

The sweeping unit 150 may generate a sweeping shape using the selected cross-sectional shape template FT _bestfit . That is, the sweeping unit 150 fits the selected cross-sectional shape template to the segment, sweeps the fitted cross-sectional shape template based on the extracted path, and generates a sweeping shape as a result of the sweeping.

At this time, the FTS-based sweeping shape thus generated is shown in the following [Table 3].

division Contents FTS _object = {FTS, FT _path } FTS-based sweeping object is defined as FTS and FT _path FT _path = {FT _position , ...} The FT _path is the set of locations to which the FT _bestfit applies FT _position = {Line _begin or Line _end , Curve _interval } FT _position is defined as straight line start point, straight line end point, curve interval

5 is a diagram illustrating a method for inversely designing a sweeping shape according to an embodiment of the present invention.

5, an apparatus for inverse designing a sweeping shape according to the present invention (hereinafter referred to as a sweeping shape inverse designing apparatus) classifies a given PCD according to a segmentation, that is, a specific criterion, As a result of classification, a plurality of PCD segments may be obtained (S410).

Next, the sweeping shape reverse design apparatus can extract the center path of each of the obtained plurality of PCD segments (S420).

Next, the sweeping shape reverse design apparatus can extract sections for each point of the extracted center path (S430).

Next, the sweeping shape reverse design apparatus compares the obtained section with the similarity of predefined shape templates, and selects the most similar shape template as a cross-sectional shape template as a result of the comparison (S440).

That is, the sweeping shape inverse designing apparatus calculates the similarity between the obtained section and the predefined shape templates (S441), and selects one shape template determined to be the most similar as a result of the calculation as a section shape template (S442 ).

Next, the sweeping shape reverse design apparatus can automatically generate the sweeping shape using the selected cross-sectional shape template (S450). Specifically, the sweeping shape reverse designing device fits the selected cross-sectional shape template to the segment, and sweeps the fitted cross-sectional shape template based on the extracted path to generate a sweeping shape as a result of the sweeping.

It is to be understood that the present invention is not limited to these embodiments, and all of the elements constituting the embodiments of the present invention described above are described as being combined or operated together. That is, within the scope of the present invention, all of the components may be selectively coupled to one or more of them. In addition, although all of the components may be implemented as one independent hardware, some or all of the components may be selectively combined to perform a part or all of the functions in one or a plurality of hardware. As shown in FIG. In addition, such a computer program may be stored in a computer-readable medium such as a USB memory, a CD disk, a flash memory, etc., and read and executed by a computer, thereby implementing embodiments of the present invention. As the storage medium of the computer program, a magnetic recording medium, an optical recording medium, a carrier wave medium, or the like may be included.

While the invention has been shown and described with reference to certain embodiments thereof, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the scope of the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be construed according to the following claims, and all technical ideas within the scope of equivalents should be construed as falling within the scope of the present invention.

110: Segmentation unit
120: Skeleton extractor
130: Segment section extracting section
140:
150: sweeping part

Claims (10)

A segmentation unit for segmenting a given PCD to obtain a plurality of PCD segments;
A skeleton extracting unit for extracting a center path of each of the obtained plurality of PCD segments;
A segment section extracting unit for projecting the given PCD of the 3D in a two-dimensional cross-section and extracting a section for each point of the extracted center path;
A similarity calculator for comparing the acquired section with predefined shape templates to calculate respective similarities and selecting one shape template determined to be the most similar to the calculated result as a sectional shape template; And
And a sweeping unit for automatically generating a sweeping shape using the selected cross-sectional shape template,
The similarity calculation unit compares the extracted shape templates with the extracted sections using the following equations, and calculates a similarity degree by using a device for inverse designing a sweeping shape for selecting a shape template closest to 1.0 from the comparison result as the cross- :

Here, the FT _smooth refers to a value obtained by extracting a polyline from a section extracted for each point and then converting the extracted polyline into a shape template XML grammar. The length (FT _smooth ) Means the length of the defined FT _smooth , the FT _fitting means the shape templates of the predefined XML grammar, and the length (FT _fitting ) means the length of the FT _fitting . The method according to claim 1,
Wherein the segmentation unit comprises:
Wherein a plurality of PCD segments are obtained as a result of classifying the given PCD according to a preset reference, and classifying the obtained PCD segments. The method according to claim 1,
Wherein the skeleton extracting unit comprises:
Wherein the central path of each of the plurality of PCD segments is extracted using an L1-medial condition based skeleton extraction technique. delete The method according to claim 1,
The sweeping unit includes:
And a sweeping shape is generated by sweeping the selected cross-sectional shape template based on a center path previously extracted and fitting the selected cross-sectional shape template to the segment, Device. A segmentation step of segmenting a given PCD to obtain a plurality of PCD segments;
A skeleton extracting step of extracting a center path of each of the obtained plurality of PCD segments;
A segmentation section extracting step of projecting the given PCD of a three-dimensional plane onto a two-dimensional cross-section, and extracting a section for each point of the extracted center path;
Calculating similarity by comparing the acquired section with predefined shape templates, and selecting one of the shape templates determined to be most similar to the calculated result as a section template; And
And a sweeping step of automatically generating a sweeping shape using the selected cross-sectional shape template,
The similarity calculation step may include:
A method for inverse designing a sweeping shape that compares the extracted shape sections with the defined shape templates using the following equation and selects a shape template closest to 1.0 from the comparison result as the cross-sectional shape template:

Here, the FT _smooth refers to a value obtained by extracting a polyline from a section extracted for each point and then converting the extracted polyline into a shape template XML grammar. The length (FT _smooth ) Means the length of the defined FT _smooth , the FT _fitting means the shape templates of the predefined XML grammar, and the length (FT _fitting ) means the length of the FT _fitting . The method according to claim 6,
Wherein the segmentation step comprises:
And classifying the given PCD according to a preset reference, and obtaining a plurality of PCD segments as a result of classification. The method according to claim 6,
In the skeleton extracting step,
Wherein the central path of each of the plurality of PCD segments is extracted using an L1-medial condition based skeleton extraction technique. delete The method according to claim 6,
Wherein the sweeping step comprises:
And a sweeping shape is generated by sweeping the selected cross-sectional shape template based on a center path previously extracted and fitting the selected cross-sectional shape template to the segment, Way.

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