WO2022220661A1

WO2022220661A1 - 3d cad data-conversion method and program for 3d printer outputting, and device therefor

Info

Publication number: WO2022220661A1
Application number: PCT/KR2022/005555
Authority: WO
Inventors: 최이규; 이규홍
Original assignee: 주식회사 팀솔루션
Priority date: 2021-04-16
Filing date: 2022-04-18
Publication date: 2022-10-20
Also published as: KR20220143612A; KR102476800B1; KR102417745B1

Abstract

A 3D computer aided design (CAD) data-conversion method for 3-dimensional (3D) printer outputting, according to one embodiment of the present invention, comprises steps of: receiving 3D CAD data; reducing, to a preset ratio, a 3D modeling object included in the 3D CAD data to convert the 3D CAD data into data for 3D printer outputting; and transmitting the data for 3D printer outputting to a 3D printer, wherein the step of converting the 3D CAD data into the data for 3D printer outputting can comprise steps of: dividing a plane and an edge in the 3D modeling object; parallelly moving, by a certain displacement derived by considering the preset ratio and preset thickness, the divided plane in the direction of a first normal vector included in the vertex of the divided plane; and moving the divided edge in the direction that is vertical to a second normal vector direction of an edge surface and is parallel to the planar direction of the edge surface, by referring to the vertex position of the parallelly moved plane.

Description

3D CAD data conversion method for 3D printer output, program and device therefor

The present specification proposes a method and apparatus for converting 3D (Dimension) CAD (Computer Aided Design) data into data in a form suitable for output by a 3D printer.

A 3D printer is a device that implements/outputs a three-dimensional three-dimensional shape based on a 3D drawing. 3D printers may be classified into various types according to a material and an output method of an output.

The most commonly encountered printing method is the FDM (Fused deposition modeling) method in which the material is heated and sprayed with a nozzle, and the general output resolution is about 0.1 to 0.4 mm. The printable size is determined by the size of the bed provided.

DfAM (Design for Additive Manufacturing) is a concept in which additive elements are added to the existing process design to maximize the advantages of 3D printing. In other words, it is a modeling method that adapts an existing process to a 3D printer. An example of the existing process may be a 3D CAD model, and in order to output the 3D CAD model to a 3D printer, a step of converting the 3D CAD model into a data format suitable for the 3D printer is required. For example, a process of scaling (eg, reducing/enlarging) a 3D CAD model to a size that can be printed with a 3D printer is required.

Essentially, scaling the original 3D CAD model to the size of the 3D printer's output is no big deal in the case of magnification. However, in the case of reduction, if the structure after scaling exceeds the output limit of the 3D printer, some components may be lost. For example, when the thickness of some components is reduced to less than the diameter of the 3D printer nozzle according to the reduction (ie, out of the resolution range of the 3D printer), the corresponding components are lost due to inability to print during the conversion process. Alternatively, similarly, even if the thickness of the structure after reduction satisfies the resolution range of the 3D printer, in order to maintain the quality of the 3D printer output above a certain level, the minimum thickness condition for each component to ensure a structure with a certain strength or higher satisfaction is required.

In the past, in order to solve this problem, the user had to select a 3D model by predicting the final result, manually using a 3D design tool, and then modify it in a form that can be printed with a 3D printer. However, this inevitably imposes a very heavy burden on the user in terms of time and cost.

According to an embodiment of the present invention proposed to solve the above problems, there is provided a method of converting 3D CAD (Computer Aided Design) data for output to a 3D (Dimension) printer, the method comprising: receiving the 3D CAD data; reducing the 3D modeling object included in the 3D CAD data to a preset ratio, and converting the 3D CAD data into data for output to a 3D printer; and transmitting the data for output to the 3D printer to the 3D printer. Including, wherein the converting of the 3D CAD data to the data for output to the 3D printer comprises: distinguishing a surface and a border in the 3D modeling object; moving the divided surface in parallel by a displacement derived in consideration of the predetermined ratio and predetermined thickness in the direction of a first normal vector of a vertex of the divided surface; and moving the divided edge in a direction perpendicular to a second normal vector direction of the edge surface and parallel to the surface direction of the edge surface with reference to the vertex position of the parallel-moved surface; may include.

In addition, according to another embodiment of the present invention, there is provided a 3D CAD (Computer Aided Design) data conversion program for 3D (Dimension) printer output, comprising: an operation for receiving the 3D CAD data; an operation of reducing the 3D modeling object included in the 3D CAD data to a preset ratio and converting the 3D CAD data into data for output to a 3D printer; and transmitting the data for output to the 3D printer to the 3D printer. However, the operation of converting the 3D CAD data into the data for output to the 3D printer may include an operation of dividing a surface and a border in the 3D modeling object; an operation of moving the divided surface in parallel by a displacement derived in consideration of the predetermined ratio and predetermined thickness in the direction of a normal vector of a vertex of the divided surface; and moving the divided edge in a direction perpendicular to the normal vector direction of the edge surface and parallel to the surface direction of the edge surface with reference to the vertex position of the parallel-moved surface. may be stored in a medium to perform

According to an embodiment of the present invention, since 3D CAD data is automatically converted into data for output by a 3D printer, there is no need for a user to manually work, thereby greatly reducing a user burden in terms of time and cost.

In particular, when reducing the 3D modeling object of 3D CAD data and converting it to data for 3D printer output, some components are lost or the overall shape/ratio is changed only by simple reduction conversion. had to be done. However, according to an embodiment of the present invention, since the above-described problem does not occur without the user's post-processing work, the time/cost for post-processing work is reduced, and 3D printing of 3D modeling objects with high quality is possible. It works.

Effects of the present invention are not limited thereto, and various effects will be described below in detail with reference to each embodiment.

1 is a diagram illustrating a silver surface removal technique according to an embodiment of the present invention.

2 is a diagram illustrating an embodiment of detecting a bent surface in a 3D CAD model according to an embodiment of the present invention.

3 illustrates a rendered image of a container node in a CAD drawing according to an embodiment of the present invention.

4 is a view illustrating an embodiment of distinguishing faces and edges of a flat plate-shaped 3D modeling object according to an embodiment of the present invention.

5 is a diagram illustrating a vertex normal vector of a 3D modeling object according to an embodiment of the present invention.

6 and 7 are flowcharts of a method of converting 3D CAD data for output to a 3D printer according to an embodiment of the present invention.

8 is a diagram illustrating movement transformation of a face group and an edge group according to vertex duplication removal according to an embodiment of the present invention.

9 is a diagram illustrating an embodiment of dividing/selecting a surface and an edge according to an embodiment of the present invention.

10 illustrates a method of obtaining a normal vector of a vertex according to an embodiment of the present invention.

11 illustrates a rendered image of a 3D modeling object converted according to a 3D CAD data conversion method according to an embodiment of the present invention.

Since the technology to be described below can have various changes and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail. However, this is not intended to limit the technology described below to specific embodiments, and it should be understood to include all modifications, equivalents, and substitutes included in the spirit and scope of the technology described below.

Terms such as first, second, A, and B may be used to describe various components, but the components are not limited by the above terms, and only for the purpose of distinguishing one component from other components. used only as For example, a first component may be named as a second component, and similarly, the second component may also be referred to as a first component without departing from the scope of the technology to be described below. and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items. For example, 'A and/or B' may be interpreted as meaning 'at least one of A or B'. Also, '/' may be interpreted as 'and' or 'or'.

In terms of terms used herein, the singular expression should be understood to include a plural expression unless the context clearly dictates otherwise, and terms such as "comprises" include the described feature, number, step, operation, and element. , parts or combinations thereof are to be understood, but not to exclude the possibility of the presence or addition of one or more other features or numbers, step operation components, parts or combinations thereof.

Prior to a detailed description of the drawings, it is intended to clarify that the classification of the constituent parts in the present specification is merely a division according to the main function that each constituent unit is responsible for. That is, two or more components to be described below may be combined into one component, or one component may be divided into two or more for each more subdivided function. In addition, each of the constituent units to be described below may additionally perform some or all of the functions of other constituent units in addition to the main function it is responsible for. Of course, it can also be performed by being dedicated to it.

In addition, in performing the method or operation method, each process constituting the method may occur differently from the specified order unless a specific order is clearly described in context. That is, each process may occur in the same order as specified, may be performed substantially simultaneously, or may be performed in the reverse order.

The 3D CAD data conversion apparatus proposed in the present specification is an electronic server in which an application/program implemented to perform/execute the 3D CAD data conversion method/embodiment for 3D printer output proposed in the present specification is installed and executed in advance. This may correspond to /device/device. Therefore, even if not separately described below, the method/embodiment proposed in the present specification may be interpreted as being performed/executed through the server/device/device in which the application/program is running, and the An operation may be interpreted as an operation/function/operation of the application/program. Hereinafter, for convenience of description, '3D CAD data conversion apparatus' will be abbreviated as 'data conversion apparatus'.

First, technical terms used in the description of the present invention will be defined, and then the present invention will be described in detail.

- REV (AVEVA Review Model Format): 3D CAD data format and extension created by Aveva Marine

- Container: In REV format, it means a node of a hierarchical structure.

- Primitive: A basic geometric element in a 3D model, where each primitive is represented by a unique geometric definition.

- Mesh: 3D model structured with polygons and vertices

- Polygon/face: A polygon composed of 3 or more vertices on the same plane

- Vertex: A set of three coordinates representing a position in 3D space (eg (x, y, z))

- Normal vector: A vector of length 1 representing the direction of the plane (ie perpendicular to the plane).

- 3D model: A data set or file with shape information that can be represented in 3D space.

- 3D modeling object: 3D object whose appearance and shape are defined by the 3D model

These technical terms may be defined as described above, but are not necessarily limited thereto, and may be used as dictionary definitions or definitions commonly recognized by those skilled in the art.

This specification basically proposes a method of converting 3D CAD data into data that can be output by a 3D printer. In other words, a method for converting 3D CAD data to DfAM is proposed.

In the case of 3D CAD data used in the shipbuilding industry, the size of the 3D modeling object is very large and it is impossible to output it directly with a 3D printer. . However, when the thickness of some components is reduced to less than the minimum nozzle diameter/thickness (ie, resolution) of the 3D printer during the scaling/reducing process, the 3D printer cannot output the corresponding partial components and is lost. Furthermore, even if the scaled/reduced thickness satisfies the resolution range of the 3D printer, if the scaled/reduced thickness is reduced to a too thin thickness, the strength/durability of the 3D modeling object may be very weakly output.

Therefore, in the data conversion work for 3D printer output, while maintaining the overall shape and proportion of the 3D printed 3D modeling object, a separate data processing process is performed so that some components are not lost and output with a certain level of strength/durability. is required

In this specification, such a processing method is mainly proposed in the 3D CAD data conversion method, and the technology and concept underlying the present invention will be described first.

REV file is a 3D model format created by AVEVA, and REV file is divided into REV and RVM extensions, and each corresponds to ASCII/binary format.

A REV file consists of a container set with metadata and actual model information to describe the file, and the container set forms a tree structure. A container node may include other container nodes (ie, nested container nodes).

A container node, particularly a terminal node, may be composed of a set of primitive data. Primitive data is a data structure expressed by the mathematical definition of a model for each type, and there are meshes, blocks, pipes, cones, etc., and these determine the shape of the 3D modeling object.

A mesh is a 3D model made up of a set of polygons. In REV, mesh primitives have a hierarchical structure that follows face group-face-loop-vertex (FACET_GROUP - FACET - LOOP - VERTICES). A vertex consists of 3D vertex coordinates and a vertex normal vector. Here, the vertex normal vector is an attribute given to the vertex, indicating a viewing direction with respect to the vertex, and may be obtained as a normal vector perpendicular to the polygonal plane to which the vertex belongs. Information on vertices (ie, vertex information) may be stored by matching with polygons to which each vertex belongs.

The mesh primitive data structure is suitable for expressing parts cut out of a plate, and one face group is a combination of a face cut off the edge of a wide plate (hereinafter referred to as 'border') and a loop that is a hole cut inside. Because it can be expressed as Since the container tree structure of REV is a hierarchical structure, it is easy for the user to activate only the necessary parts or to use it as an infrastructure for merging and managing sub-steps around the necessary nodes.

In computer graphics, face selection is a technique of filtering out the invisible face by comparing the polygon's normal vector and the gaze vector. This is also called a back face culling technique.

The polygon to be drawn based on the gaze direction 150 has an angle of 90 degrees or less, but in reality, it is possible to select only with the order of rotation of the vertices (110, 130), and in this case, it is possible to remove the hidden surface without calculating the angle between the vectors. .

Mesh simplification or mesh decimation is a technique for reducing the number of vertices in a 3D model according to a predetermined rule. Since the size and quality of the lightweight model have a trade-off relationship, an adaptive technique for preserving the shape by varying the degree of weight reduction according to the shape and feature points of the model can be performed.

As shown in FIG. 2 , in the real world, artifacts usually have corners. It can be seen that a sharp change in the plane normal vector occurs at a cut surface, a bent surface, or a boundary between a surface and a surface. Most 3D modeling objects, which are objects expressed in 3D CAD data, are artifacts, and therefore, the same characteristics are also found in 3D CAD data.

With this in mind, edge features can be detected or preserved by using the amount of change in the normal vector as error metrics. This is being used in research such as feature preserving mesh smoothing.

A characteristic of 3D modeling objects in 3D CAD data (especially ship 3D CAD data) is that many parts are composed of plate processing. The part plate of the ship is composed of a wide surface and a cut surface (hereinafter referred to as an edge). In the 3D modeling object, the terminal node represents a small unit part machined from the plate. A terminal node is managed as a single component, but as a set of polygons consisting of a series of vertices, there is no additional information.

The actual ship's assembly block unit occupies a volume of about 25Х25Х25㎥. The thickness of the steel plate used in ships is about 20 mm. The bed area of the 3D printer is about 300Х300㎟, and each side can be printed with a length of about 250mm. The output resolution (ie, nozzle thickness/diameter) of the FDM 3D printer is about 0.4 mm, but a value of 2 mm may be set as the minimum thickness for the structural strength of the 3D modeling object during 3D printing. However, the present invention is not limited thereto, and the minimum thickness may be directly set/adjusted by the user as a constant value.

That is, the 3D modeling object included in the 3D CAD data may be reduced and scaled for output by a 3D printer, and in this case, the thickness of the surface may be selectively enlarged so as not to be reduced below a preset minimum thickness. That is, the data conversion apparatus scales/reduces the overall 3D modeling object at a predetermined ratio in data conversion for 3D printer output, but selectively for the reduced thickness to a minimum thickness (eg, 2 mm) or less can be enlarged to

However, there are several problems to be solved as follows in this data conversion.

In 3D CAD data, vertices and polygons constituting the mesh have only information input to the rendering algorithm, and there is no geometric relationship information between them. Accordingly, there is a problem in that it is not possible to know which is a surface and which is an edge only with 3D CAD data. In the past, in order to solve this problem, the user had no choice but to determine which part is the face and which is the border based on the directly rendered result. Therefore, in the present specification, a method for the data conversion apparatus to determine where is a face and where is an edge in a 3D modeling object based on 3D CAD data is proposed as shown in FIG. 4 .

Vertex information included in 3D CAD data includes normal vector information for each vertex, but does not include information on normal vectors representing polygons formed by each vertex. Also, even if polygon tables are adjacent to each other in the data structure of 3D CAD data, it is not guaranteed that polygons corresponding to the table are physically adjacent to each other.

Accordingly, the data conversion apparatus according to an embodiment of the present specification searches all polygons constituting the container node and based on the polygon properties (eg, normal vector-1 (410-1 to 460) of each polygon). After grouping into at least one

face group

410, 420 or at least one edge group 430 to 460, the data structure may be generated by arranging each group based on the actual physical structure.

More specifically, the data conversion apparatus may search all polygons constituting the 3D modeling object, and may group the searched polygons into

face groups

410 and 420 or border groups 430 to 460 by properties. . Here, as an attribute used as a grouping criterion, for example, normal vectors 410-1 to 460 of polygons may be used. That is, the data conversion apparatus may extract the normal vectors 410-1 to 460 representing each of the found polygons, and the

face groups

410 and 420 based on the direction of the extracted normal vectors 410-1 to 460. Alternatively, it may be grouped into border groups 430 to 460. For example, the data conversion apparatus is a plane for polygons in which the angle between the normal vectors 410-1 to 460-1 extracted from two adjacent polygons is within a preset angle range (eg, 45 degrees). Groups may be grouped into

groups

410 and 420 . Similarly, the data conversion apparatus performs border group for polygons in which the angle between the normal vectors 410-1 to 460-1 extracted from two adjacent polygons exceeds a preset angle range (eg, 45 degrees). (430-460) can be grouped.

As described above in FIG. 4 , when the division of the surface and the edge is completed, data for 3D printer output can be generated by applying different scaling methods to the divided surface and the edge as follows.

- With respect to the plane: In the direction of the normal vector of each vertex, it moves in parallel by the displacement derived in consideration of the preset ratio and the preset thickness.

- With respect to the border: referring to the position of the parallel-moved surface (especially the vertex position), it moves in a direction perpendicular to the normal vector direction of the border face and parallel to the face direction of the border face

That is, after the data transformation device scales the face (i.e., after translating the vertices of the face), it scales the border based on the position of the scaled face to maintain a single closed surface (i.e., the vertex of the border is converted to that of the face). can be translated to the vertex position).

However, one problem that may occur here is that, as shown in FIG. 5 , the conversion form/method of a face and a border is different, and any polygon does not share vertex information with a neighboring polygon. Accordingly, there arises a problem that the border cannot refer to the direction of the normal vector of the polygon of the adjacent face at the boundary line with the face. This is because a single closed curved surface can be maintained only when the edge accurately knows the position of the parallelized surface and scaled (or translated) based on/referring to it. In other words, when scaling without referring to their respective positions, a single closed curved surface is not maintained because the gap between the surface and the border is widened. may occur.

In order to solve this problem, the present specification proposes a method of converting the data structure of 3D CAD data so that all polygons can refer to the geometric information of the vertices. Briefly, the data conversion apparatus may generate a vertex list for all vertices constituting a container node (ie, a 3D modeling object), and convert the 3D CAD data so that all polygons of the corresponding vertex list are accessible. Furthermore, the data conversion device can update the position of the vertices included in the face in real time according to the scaling (or translation) of the face, and the border is scaled (or translated) by referring to the updated position of the vertex of the face. As a result, it is possible to maintain a single closed curved surface with the surface.

As such, a method of data transformation based on the vertex list will be described in detail below with reference to FIGS. 6 and 7 (in particular, steps S702, S703, and S709 of FIG. 7).

In particular, the flowchart of FIG. 7 is a flowchart illustrating each step of FIG. 6 in more subdivision. Step S601 of FIG. 6 is step S701 of FIG. 7, and step S602 of FIG. 6 is steps S702 to S709 of FIG. Step S603 corresponds to step S710 of FIG. 7 , respectively.

6 and 7, first, the data conversion apparatus may receive 3D CAD data (S601). At this time, the input 3D CAD data may correspond to, for example, REV file/data (S701).

Next, the data conversion apparatus may reduce (or scale) the 3D modeling object included in the 3D CAD data at a preset ratio to convert the 3D CAD data into data for output to a 3D printer. This step may be subdivided into steps S702 to S709 of FIG. 7 as follows.

First, the data conversion apparatus may search for all vertices included in the 3D modeling object and obtain a normal vector for the searched vertices (S702). To this end, the data conversion apparatus may read/read/recognize container nodes included in 3D CAD data, and search all vertices constituting each polygon of the 3D modeling object and their normal vectors.

In this case, the data conversion apparatus may exclude vertices (ie, overlapping vertices) that overlap with other vertices or are adjacent to each other by a predetermined interval or less among the found vertices.

Since the polygons adjacent to the specific coordinates each store coordinates for each polygon, the number of adjacent polygons is overlapped with vertices. In this specification, instead of removing such overlapping vertices between polygons, a method of sharing vertices between polygons is proposed. In this case, as shown in FIG. 8 , when the polygon group determined as a face is moved, the edge group sharing the vertex with the polygon group is also naturally stretched according to the movement of the face group. This will be described in more detail below.

Referring back to FIG. 7 , next, the data conversion apparatus may generate a vertex list including deduplicated vertex information ( S703 ). More specifically, the data conversion apparatus may generate a vertex list by assigning different indices to all vertices (excluding duplicates) found in step S702 (that is, indexing all vertices to generate the vertex list) . The data conversion apparatus may match and store an index assigned to each vertex to a polygon corresponding to each vertex based on vertex information stored in the 3D CAD data. For example, when the first vertex and the first polygon are stored in vertex information to match each other and the first index is assigned to the first vertex according to the generation of the vertex list, the data conversion device converts the first index to the first polygon You can match and store (or generate data).

In this way, all vertices (except duplicates) composing the container node create a list-up/arranged vertex list, and 3D CAD data is stored so that all polygons (especially polygons included in the border) can access the vertex list through an index. can be converted As a result, it is possible to interpret that polygons stored by matching one vertex index in the vertex list are polygons having a geometrically adjacent relationship. can Furthermore, it can be physically interpreted through the vertex information stored for each polygon, so that the data conversion apparatus can refer to the normal vector of the vertex required to search for geometrical adjacency of the border. More specifically, the data conversion device can update the vertex list with the moved vertex positions after translating the polygons of the face group. becomes a vertex that has already been updated. As a result, the data conversion device can know the exact movement position of the surface when moving the border (that is, solving the problem described above in FIG. 5), and there is no need to separately update/convert the reference vertex information for moving the border. occurs

The divided faces and edges may be moved in parallel according to the movement of the vertices included therein, and information about the moved vertices may be reflected and updated in the vertex list. A method of scaling a face and an edge based on the vertex movement will be described later in detail in step S708.

Next, the data conversion apparatus may obtain a plane vector (S704). Here, the face vector refers to a normal vector indicating the direction a single face (face/polygon) points. Such a surface vector may be calculated by cross-producting two vectors formed by three consecutive vertices constituting the surface, or may be calculated by adding up all vertex normal vectors of the vertices and then normalizing them. The surface vector calculated in this way is used as a variable of the normal vector change amount when determining the surface group later.

Next, the data conversion apparatus may generate a mesh (ie, a 3D modeling object mesh) composed of all the found polygons (S705). Next, the data conversion apparatus may select a face group from the generated mesh (S706) to classify/select a face and an edge in the 3D modeling object (S707). A method of distinguishing a surface and an edge is largely divided into two types depending on whether the 3D modeling object forms a curved surface, and when the 3D modeling object is not a curved surface, the technique described above in FIG. 4 may be applied. When the 3D modeling object forms a curved surface, the technique described later in FIG. 9 may be applied.

As shown in FIG. 9 , the data conversion apparatus may determine whether the 3D modeling object forms a curved surface by determining the bent portion based on the amount of change of the polygon normal vector, and if it is determined that the 3D modeling object forms a curved surface, the area of each surface You can distinguish/select faces and borders based on More specifically, the data conversion device can determine the surface that changes smoothly when the angle between the two adjacent surfaces is within the threshold value by using the angle between the normal vectors of the two adjacent surfaces as the amount of change, can judge The threshold value used at this time may be derived heuristically as a value capable of discriminating a face group with an accuracy greater than or equal to a preset ratio through repeated experiments. The data conversion device calculates the area of each face in the 3D modeling object constituting the curved surface, divides/selects the widest face into upper/lower (i.e., face group), and separates/selects other faces into side (i.e., border group) can be selected.

Referring back to FIG. 7 , next, the data conversion apparatus may convert 3D CAD data into data for 3D printer output by applying different scaling methods to the divided faces and edges ( S708 ). In more detail, the data conversion apparatus first calculates the divided surface in the direction of the normal vector that the vertex of the divided surface has, considering the scaling/reduction ratio and the preset minimum thickness (eg, 2 mm). It can be translated as much as the displacement. After completing the parallel movement of the face, the data conversion device moves the divided border in a direction perpendicular to the normal vector direction of the border face and parallel to the face direction of the border face with reference to the vertex position of the moved face. can

The vertex normal vector used in step S708 may mean an average normal vector (refer to this figure) obtained by adding all normal vectors of each overlapping/shared vertex before vertex deduplication. Such a vertex normal vector may be obtained during a vertex deduplication operation and stored together with information about each vertex. When obtaining the vertex normal vector, the normal vector of the vertex belonging to the border is not included.

That is, the data conversion device first scales and moves the face, and then moves the border in the direction of movement of the face in parallel with reference to the vertex position of the moved face so that the moved face and the edge are interconnected to form a single closed curved surface. scaling can be performed. In particular, the data conversion apparatus can utilize vertices and vertex lists for scaling (or translation) of faces and edges as follows.

As an embodiment, in translating the plane, the data conversion apparatus may first move all vertices of the indexed plane in parallel by a predetermined displacement in the direction of a normal vector of each vertex. If this is expressed as an equation, it is the same as in Equation 1, and a preset displacement may be derived by Equation 2.

In Equation 1, P is the vertex coordinates after translation, Po is the vertex coordinates before translation, d is a preset displacement,

are the normal vectors of the vertices before translation, respectively.

In Equation 2, S is a preset ratio (scaling ratio), Lr is an actual size of the 3D modeling object, Lp is a 3D printer output size of the 3D modeling object, and tp is a preset thickness. In particular, the preset thickness is a 3D printer output thickness intended by the user, and may be directly set/input as a constant value by the user within a range equal to or greater than the above-mentioned minimum thickness. As such, through Equation 2, since the thickness of the 3D modeling object is set to a value equal to or greater than the preset thickness, the resolution range of the 3D printer is satisfied, and the output of a 3D modeling object having durability above a certain level is possible.

The data conversion apparatus may update the vertex list by reflecting the positions of the vertices moved according to Equations 1 and 2, and may move the border with reference to the vertex positions of the updated vertex list.

In more detail, the data conversion apparatus may obtain the updated position of the vertex by searching the updated vertex list for an index matched for each polygon included in the divided border. The data conversion apparatus may move the edge in a direction perpendicular to the normal vector direction and parallel to the plane direction of the edge with reference to the obtained position of the vertex.

In other words, since the vertices shared between the face and the edge are moved according to the movement of the face, as a result, the edge sharing the moved vertex is also naturally moved along with the movement of the face. That is, even if the data conversion apparatus moves only the face group, due to the sharing of vertices with the border, the border automatically moves while maintaining the face group and the closed surface. All polygons in the mesh refer to their vertices in the vertex list. As a result, physically adjacent, neighboring polygons share a specific vertex. At this time, if the polygon forming the face and the polygon forming the border share a specific vertex, the position of the shared vertex is updated in the vertex list as the polygon forming the face is moved and transformed in the face vector direction. By referencing the vertex, the changed position of the vertex is automatically reflected. As a result, the polygon of the edge may be automatically deformed according to the deformation of the surface at the intended scaling ratio while forming a closed curved surface.

Referring back to FIG. 7 , the data conversion apparatus may convert 3D CAD data into data for 3D printer output by sequentially performing steps S702 to S709 described above. The data conversion apparatus may transmit data for 3D printer output to the 3D printer (S603) so that the 3D printer 3D prints the scaled 3D modeling object (S709).

Each step proposed in the flowcharts of FIGS. 6 and 7 may be interpreted as a function/operation of an application/program designed to perform the 3D CAD data conversion method. Similarly, each of the steps proposed in the flowcharts of FIGS. 6 and 7 may be interpreted as being performed by each component of the data conversion apparatus classified according to a function.

In particular, Fig. 11 (a) is an original 3D modeling object of 3D CAD data, and Fig. 11 (b) is a 3D modeling object scaled version (or reduced version) of data for 3D printer output converted according to an embodiment of the present invention, Fig. 11(c) is a partially enlarged view of Fig. 11(a), and Fig. 11(d) is a partially enlarged view of Fig. 11(b).

This figure is a rendering image derived from a situation where Lr is 25,000 mm, Lp is 250 mm, and d is 200 mm, respectively.

Referring to FIG. 11 , it can be seen that the original ratio and shape/form of the 3D modeling object are reduced while being maintained, but only the thickness (or the width of the border) of each component is enlarged. That is, according to the embodiment proposed in this specification, even if the 3D modeling object included in the 3D CAD data is scaled/reduced for output to the 3D printer, the 3D printer will be outputted with a certain level of durability without a lost configuration. It has the effect that it can.

Meanwhile, although not shown in this drawing, an embodiment in which data for output to a 3D printer is generated by intentionally losing some configuration of a 3D modeling object may also be proposed.

According to the embodiment proposed in this specification, the 3D modeling object is reduced and converted/scaled to a size that can be printed with a 3D printer, but the thickness is maintained above the minimum thickness, so the effect of partially expanding/converting/scaling for a specific component/element is Occurs. As a result, although the interval between the components is shortened, the thickness of the components itself is enlarged or maintained, so that the separated components may contact each other or overlap each other. In this case, when the 3D printer is output, there may be a problem in that the appearance/shape of the 3D modeling object is output differently from the original. Accordingly, in the present specification, as a result of data conversion, when configurations that are shorter than a predetermined interval or overlap each other are found as described above, a method for integrating the configurations into one configuration is proposed.

That is, when the components satisfying the above condition are found, the data conversion apparatus may convert the data by integrating the components into one component or by intentionally deleting/losing any one of the components. For example, when the data conversion device finds first and second pillar configurations in contact with or overlapping each other, the first and second pillar configurations are integrated into the third configuration, or the first or second pillar configurations are intentionally combined. Can be deleted/deleted. In the former case, the position of the third configuration may be disposed at the center of the first and second pillar configurations.

However, as a precondition for carrying out the present embodiment, it is premised that the components to be replaced or lost are all components having the same/similar shape/outer appearance. When described based on the above example, it is assumed that the first and second pillars to be replaced or lost have the same geometric properties (eg, height, shape, appearance, thickness, size, etc.).

Embodiments according to the present invention may be implemented by various means, for example, hardware, firmware, software, or a combination thereof. In the case of implementation by hardware, an embodiment of the present invention provides one or more application specific integrated circuits (ASICs), digital signal processors (DSPs), digital signal processing devices (DSPDs), programmable logic devices (PLDs), FPGAs ( field programmable gate arrays), a processor, a controller, a microcontroller, a microprocessor, and the like.

In addition, in the case of implementation by firmware or software, an embodiment of the present invention is implemented in the form of a module, procedure, function, etc. that performs the functions or operations described above, and is stored in a recording medium readable through various computer means. can be recorded. Here, the recording medium may include a program command, a data file, a data structure, etc. alone or in combination. The program instructions recorded on the recording medium may be specially designed and configured for the present invention, or may be known and available to those skilled in the art of computer software. For example, the recording medium includes a magnetic medium such as a hard disk, a floppy disk, and a magnetic tape, an optical recording medium such as a compact disk read only memory (CD-ROM), a digital video disk (DVD), and a floppy disk. magneto-optical media, such as a disk, and hardware devices specially configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions may include high-level language codes that can be executed by a computer using an interpreter or the like as well as machine language codes such as those generated by a compiler. Such hardware devices may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

In addition, the device or terminal according to the present invention may be driven by a command that causes one or more processors to perform the functions and processes described above. For example, such instructions may include interpreted instructions, such as script instructions, such as JavaScript or ECMAScript instructions, or executable code or other instructions stored on a computer-readable medium. Furthermore, the device according to the present invention may be implemented in a distributed manner over a network, such as a server farm, or may be implemented in a single computer device.

Further, a computer program (also known as a program, software, software application, script or code) mounted on the device according to the invention and executing the method according to the invention includes compiled or interpreted language or a priori or procedural language. It can be written in any form of programming language, and can be deployed in any form, including stand-alone programs, modules, components, subroutines, or other units suitable for use in a computer environment. A computer program does not necessarily correspond to a file in a file system. A program may be placed in a single file provided to the requested program, or in multiple interacting files (eg, files that store one or more modules, subprograms, or portions of code), or portions of files that hold other programs or data. (eg, one or more scripts stored within a markup language document). A computer program may be deployed to be executed on a single computer or multiple computers located at one site or distributed over a plurality of sites and interconnected by a communication network.

Although each drawing has been described separately for convenience of description, it is also possible to design to implement a new embodiment by merging the embodiments described in each drawing. In addition, the present invention is not limited to the configuration and method of the embodiments described as described above, but the above-described embodiments are configured by selectively combining all or part of each embodiment so that various modifications can be made. it might be

In addition, although preferred embodiments have been illustrated and described above, the present specification is not limited to the specific embodiments described above, and those of ordinary skill in the art to which the specification belongs without departing from the gist of the claims Various modifications are possible by the person, of course, these modifications should not be individually understood from the technical spirit or perspective of the present specification.

Claims

A method of converting 3D CAD (Computer Aided Design) data for 3D (Dimension) printer output, the method comprising:

receiving the 3D CAD data;

reducing the 3D modeling object included in the 3D CAD data to a preset ratio, and converting the 3D CAD data into data for output to a 3D printer; and

transmitting the data for output to the 3D printer to the 3D printer; including,

The step of converting the 3D CAD data into the data for output to the 3D printer comprises:

distinguishing a face and a border from the 3D modeling object;

moving the divided surface in parallel by a displacement derived in consideration of the predetermined ratio and predetermined thickness in the direction of a first normal vector of a vertex of the divided surface; and

moving the divided edge in a direction perpendicular to a second normal vector direction of the edge surface and parallel to the surface direction of the edge surface with reference to the vertex position of the parallel-moved surface; Containing, 3D CAD data conversion method for 3D printer output.
The method of claim 1,

The step of separating the face and the border is,

searching for all polygons constituting the 3D modeling object;

grouping the found polygons into face groups or border groups by properties;

generating a mesh composed of all the polygons;

selecting the face group from the generated mesh and calculating an interval between the selected face groups; and

generating a data structure in which the face group or the edge group is arranged according to the calculated interval; Containing, 3D CAD data conversion method for 3D printer output.
3. The method of claim 2,

The step of grouping the searched polygons by the properties comprises:

extracting a normal vector representing each of the searched polygons;

When the angle between normal vectors extracted from adjacent polygons among the searched polygons is less than or equal to a preset angle range, the adjacent polygons are grouped into the face group, and the angle between the extracted normal vectors exceeds the preset angle range grouping the adjacent polygons into the border group; Containing, 3D CAD data conversion method for 3D printer output.
The method of claim 1,

When the 3D CAD data includes vertex information for each polygon constituting the 3D modeling object, converting the 3D CAD data into the data for output to the 3D printer includes:

searching for all vertices included in the 3D modeling object;

generating a vertex list by assigning different indices to each of the found vertices; and

storing an index assigned to each vertex by matching with a polygon corresponding to each vertex based on the vertex information; Containing, 3D CAD data conversion method for 3D printer output.
5. The method of claim 4,

The step of generating the vertex list comprises:

and generating the vertex list by excluding vertices that overlap with other vertices or are adjacent to each other by a predetermined interval or less among the searched vertices.
5. The method of claim 4,

The step of moving the divided surface in parallel is,

moving all the vertices of the surface to which the index is assigned in parallel by the derived displacement in the direction of the first normal vector; and

updating the vertex list by reflecting the position of the moved vertex; A 3D CAD data conversion method for 3D printer output, including.
7. The method of claim 6,

The step of translating all the vertices of the surface is performed based on Equation 1, 3D CAD data conversion method for 3D printer output.

[Equation 1]

wherein P is the vertex coordinates after translation, Po is the vertex coordinates before translation, and d is the derived displacement, the
is the first normal vector of the vertex before the translation.
8. The method of claim 7,

The 3D CAD data conversion method for 3D printer output, wherein the first normal vector of the vertex overlapping with the other vertices is defined as an average normal vector obtained by adding all of the normal vectors of each overlapping vertex.
8. The method of claim 7,

The displacement is derived based on Equation 2, 3D CAD data conversion method for 3D printer output.

[Equation 2]

wherein S is the preset ratio, Lr is the actual size of the 3D modeling object, Lp is the 3D printer output size of the 3D modeling object, and tp is the preset thickness.
10. The method of claim 9,

The predetermined thickness is,

3D CAD data conversion method for 3D printer output, which is a constant value input by a user in a thickness range equal to or greater than the resolution of the 3D printer.
7. The method of claim 6,

The step of moving the divided border is,

searching the updated vertex list for an index matched for each polygon included in the divided border;

obtaining a position of an updated vertex stored in correspondence with the searched index; and

moving the divided edge in a direction perpendicular to the second normal vector direction and parallel to the surface direction of the edge face with reference to the updated vertex position; Containing, 3D CAD data conversion method for 3D printer output.
In the conversion program of 3D CAD (Computer Aided Design) data for 3D (Dimension) printer output,

an operation for receiving the 3D CAD data;

an operation of reducing the 3D modeling object included in the 3D CAD data to a preset ratio and converting the 3D CAD data into data for output to a 3D printer; and

an operation of transmitting the data for output to the 3D printer to the 3D printer; do, but

The operation of converting the 3D CAD data into data for output to the 3D printer comprises:

an operation of distinguishing a face and a border in the 3D modeling object;

an operation of moving the divided surface in parallel by a displacement derived in consideration of the predetermined ratio and predetermined thickness in the direction of a first normal vector of a vertex of the divided surface; and

an operation of moving the divided edge in a direction perpendicular to a second normal vector direction of the edge surface and parallel to the surface direction of the edge surface with reference to the vertex position of the parallel-moved surface; to perform

3D CAD data conversion program for 3D printer output stored in recording media.
13. The method of claim 12,

The operation to distinguish the face and the border is,

an operation of searching all polygons constituting the 3D modeling object;

an operation of grouping the searched polygons into face groups or border groups for each attribute; and

an operation of generating a classified data structure for each group; containing,

3D CAD data conversion program for 3D printer output stored in recording media.
14. The method of claim 13,

The operation of grouping the searched polygons by the attribute is,

an operation of extracting a normal vector representing each of the searched polygons;

When the angle between normal vectors extracted from adjacent polygons among the searched polygons is less than or equal to a preset angle range, the adjacent polygons are grouped into the face group, and the angle between the extracted normal vectors exceeds the preset angle range grouping the adjacent polygons into the border group; comprising,

3D CAD data conversion program for 3D printer output stored in recording media.
13. The method of claim 12,

When the 3D CAD data includes vertex information for each polygon constituting the 3D modeling object, the operation of converting the 3D CAD data into data for output to the 3D printer includes:

an operation of searching for all vertices included in the 3D modeling object;

generating a vertex list by assigning different indices to each of the found vertices; and

an operation of matching and storing an index assigned to each vertex to a polygon corresponding to each vertex based on the vertex information; comprising,

3D CAD data conversion program for 3D printer output stored in recording media.
16. The method of claim 15,

The operation to create the vertex list is:

An operation of generating the vertex list by excluding vertices that overlap with other vertices from among the searched vertices or are adjacent to each other within a predetermined interval or less,

3D CAD data conversion program for 3D printer output stored in recording media.
16. The method of claim 15,

The operation of moving the divided surface in parallel is,

an operation of moving all vertices of the surface to which the index is assigned in parallel by the derived displacement in the direction of the first normal vector; and

updating the vertex list by reflecting the position of the moved vertex; comprising,

3D CAD data conversion program for 3D printer output stored in recording media.
18. The method of claim 17,

The operation of moving all vertices of the plane in parallel is performed based on Equation 1,

3D CAD data conversion program for 3D printer output stored in recording media.

[Equation 1]

wherein P is the vertex coordinates after translation, Po is the vertex coordinates before translation, and d is the derived displacement, the
is the first normal vector of the vertex before the translation.
19. The method of claim 18,

The first normal vector of the vertex overlapping with the other vertices is defined as an average normal vector obtained by adding up all normal vectors of each overlapping vertex,

3D CAD data conversion program for 3D printer output stored in recording media.
19. The method of claim 18,

The displacement is derived based on Equation 2,

3D CAD data conversion program for 3D printer output stored in recording media.

[Equation 2]

wherein S is the preset ratio, Lr is the actual size of the 3D modeling object, Lp is the 3D printer output size of the 3D modeling object, and tp is the preset thickness.
21. The method of claim 20,

The predetermined thickness is,

A constant value input by a user in a thickness range equal to or greater than the resolution of the 3D printer,

3D CAD data conversion program for 3D printer output stored in recording media.
18. The method of claim 17,

The operation of moving the divided border is,

an operation of searching the updated vertex list for an index that is matched for each polygon included in the divided border;

an operation of obtaining the position of the stored updated vertex corresponding to the searched index; and

an operation of moving the divided edge in a direction perpendicular to the second normal vector direction and parallel to a plane direction of the edge surface based on the updated vertex position; containing,

3D CAD data conversion program for 3D printer output stored in recording media.