CN110175423B - Geometric correction method of 3D printing model - Google Patents
Geometric correction method of 3D printing model Download PDFInfo
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- CN110175423B CN110175423B CN201910466731.8A CN201910466731A CN110175423B CN 110175423 B CN110175423 B CN 110175423B CN 201910466731 A CN201910466731 A CN 201910466731A CN 110175423 B CN110175423 B CN 110175423B
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Abstract
The invention discloses a geometric correction method of a 3D printing model, which comprises the steps of converting an input grid model into an initial model represented by pixels; then, simulating the 3D printing process by using a low-pass filter to obtain a simulation model; then, subtracting the simulation model and the initial model to obtain a difference model, and finding out the part where the hole filling and detail missing phenomena occur; then, carrying out geometric correction on the parts to obtain an enhanced model; and finally, converting the enhanced model into a grid model, and taking the grid model as an input model of the 3D printing software. Aiming at the phenomena of hole filling and detail loss caused by the diffusion effect of the binder in the 3D printing process, the invention adopts the low-pass filter to simulate the selective laser sintering process, can find out the parts with the hole filling and the detail loss, automatically carries out geometric correction on the parts without manual intervention, reduces the damage or loss of the detail characteristics of the product to a certain extent, and improves the precision and the quality of the product.
Description
Technical Field
The invention relates to a geometric correction method of a 3D printing model, and belongs to the technical field of 3D printing.
Background
Selective Laser Sintering (SLS) is a 3D printing technique that uses laser as a heat source to melt a binder and sinter the powder material into a shape. The Selective Laser Sintering (SLS) technology has shown wide market prospects in the aspects of new product development, mold manufacturing, small-batch product production and the like. However, during laser sintering, the diffusion of the molten binder inside the powder material can cause two side effects: hole filling and missing details. For holes in a product model, the hole area is partially or completely covered due to the diffusion effect of the adhesive, and some elongated holes are easily disappeared, as shown in fig. 1 (a). For fine features in the product model, the binder diffusion phenomenon may reduce the binder density at these locations, thereby reducing the strength of these locations, as shown in fig. 1 (b). During post-processing such as cleaning, these small parts may break, resulting in a loss of detailed features of the 3D printed product. The phenomena of hole filling and detail missing seriously affect the precision and quality of products, and are problems which are urgently needed to be solved at present.
Disclosure of Invention
Aiming at the problems in the prior art, the invention provides a geometric correction method of a 3D printing model, which adopts a low-pass filter to simulate a selective laser sintering process, can find out the part with hole filling and detail missing, automatically performs geometric correction on the part without manual intervention, can reduce the damage or missing phenomenon of the detail characteristics of a product to a certain extent, and improves the precision and quality of the product.
In order to achieve the purpose, the invention adopts the following technical scheme: a geometric correction method for a 3D printing model comprises the following steps:
step one, constructing an initial model:
firstly, slicing an input grid model to obtain a plurality of sliced layers, wherein the thickness of each sliced layer is equal to the thickness of a printing layer of a 3D printer; then converting each layer of slices into pixel models, wherein each pixel unit in each pixel model is a square, and the side length L of each square is the resolution of the 3D printer; each pixel cell has a corresponding State value, original _ State =1 indicating that the powder material of the pixel cell needs to be sintered, original _ State =0 indicating that the pixel cell does not need to be sintered; all pixels with the State value initial _ State of 1 in all the sliced layers form a 3D printing model together;
step two, constructing a simulation model:
simulating the hole filling and detail missing phenomena in the 3D printing process by using a low-pass filter, namely applying an average filter with the kernel size of NxN to each pixel model of an initial model, wherein N represents the number of pixels forming the side length of the kernel to obtain a simulation model, each pixel unit of each pixel model in the simulation model also has a corresponding State value of simulate _ State, simulate _ State =1 represents that the powder material of the pixel unit needs to be sintered, and simulate _ State =0 represents that the pixel unit does not need to be sintered;
step three, constructing a difference model:
subtracting the initial model from the simulation model to obtain a difference model, namely subtracting a corresponding pixel State value origi _ State from each pixel State value simulate _ State of the simulation model, namely subtracting a value DIF = simulate _ State-origi _ State of each pixel in the difference model, wherein the value of DIF is-1,0 or 1; DIF = -1 indicates that the lack of detail phenomenon occurs, DIF =1 indicates that the hole filling phenomenon occurs, and DIF =0 indicates that there is no change;
step four, constructing an enhanced model:
processing pixels with hole filling phenomena according to the difference model, and then processing pixels with detail loss phenomena; carrying out hole filling processing and detail missing processing on the initial model to obtain an enhanced model;
step five, reconstructing a grid model:
sequentially overlapping all slice layers in the enhanced model to obtain a voxel model; reconstructing the voxel model into a grid model by using Marching Cubes algorithm as an input model of 3D printing software
Preferably, the kernel size in the second step is N = W/2L; wherein L is the resolution of the 3D printer, W is the maximum width of the invisible slit after the hole filling phenomenon occurs, and N is rounded.
Preferably, the processing manner of the pixel with hole filling in the fourth step is as follows:
s1, numbering a pixel P and eight neighborhood pixels of the pixel P, wherein the pixel P is P and the pixel P is the pixel P with the hole filling phenomenon: #1: (X-1,Y-1), #2: (X-1,Y), #3: (X-1, Y + 1), #4: (X, Y-1), #5: (X, Y), #6: (X, Y + 1), #7: (X +1,Y-1), #8: (X +1,Y), #9: (X +1, Y + 1); wherein pixel P is numbered #5; (X, Y) represents the coordinates of the pixel P;
s2, when three or more adjacent pixels in the #1- #9 generate hole filling phenomena, setting the State value original _ State of the corresponding pixel to be 0 in the initial model according to different hole filling forms;
the processing manner of the pixel with the missing-of-detail phenomenon in the fourth step is similar to that of the pixel with the hole filling phenomenon, except that when the missing-of-detail phenomenon occurs to three or more consecutive adjacent pixels in #1- #9, the State value initial _ State of the corresponding pixel is set to 1 in the initial model according to different forms of the missing-of-detail.
Preferably, the filling form of the holes and the form of the detail loss are all in a straight line type, a right-angle type and a Chinese character tian shape,
when the hole filling form is a linear type, setting the State value original _ State of two pixels which are connected with the pixel P and vertically intersected with the linear type to be 0 in the initial model;
when the hole filling form is a right-angle form, setting the State value origi _ State of one pixel which can form a complete Chinese character 'tian' with the right-angle form as 0 in the initial model;
when the hole filling form is a shape of Chinese character 'tian', setting the State values original _ State of two pixels adjacent to the pixel P and outside the shape of Chinese character 'tian' to 0 in the initial model;
when the form of the detail loss is linear type, connecting a line through a pixel P in the initial model, and setting the State value original _ State of two pixels which are vertically intersected with the linear type as 1;
when the form of detail loss is a right-angle form, setting the State value origi _ State of a pixel which can form a complete field with the right-angle form to 1 in the initial model;
when the form of the missing detail is a shape of a Chinese character 'tian', the State values origi _ State of two pixels adjacent to the pixel P and outside the shape of the Chinese character 'tian' are set to 1 in the initial model.
Preferably, the step five of reconstructing the voxel model into the mesh model by using a Marching Cubes algorithm includes the specific steps of: processing each voxel in the voxel model one by one, solving the voxel intersected with the isosurface, and calculating the intersection point of the isosurface and the voxel edge by adopting a linear interpolation method; connecting the intersection points according to the relative position relation between each vertex in the voxel and the isosurface to obtain one or more triangular surface patches, wherein all the triangular surface patches form a grid model; where an iso-surface is a set of all points in space with some same value, it can be expressed as { (x, y, z) | f (x, y, z) = c }, where (x, y, z) represents the vertex coordinates of the voxel, f (x, y, z) represents the data value of the vertex, and c represents a given threshold.
Compared with the prior art, the invention aims at the phenomena of hole filling and detail missing caused by the diffusion effect of the binder in the 3D printing process, adopts the low-pass filter to simulate the selective laser sintering process, can find out the part where the hole filling and the detail missing occur, automatically carries out geometric correction on the part without manual intervention, reduces the phenomenon of damage or missing of the detail characteristics of the product to a certain extent, and improves the precision and the quality of the product. The method can offset the influence of the diffusion effect of the binder on the product precision, so that the geometric detail characteristics of the product damaged or completely lost in the 3D printing process can be seen again, and the product quality is improved.
Drawings
Fig. 1 is a schematic diagram of hole filling and lack of detail due to the diffusion effect of the adhesive.
FIG. 2 is a flow chart of the present invention;
FIG. 3 the test model of the present invention for determining kernel size (in mm);
FIG. 4 is an example of the print effect (in mm) of the test pattern of FIG. 3;
FIG. 5 is a numbering scheme of pixel P and its eight neighborhoods;
FIG. 6 illustrates an enhanced method of linear hole filling according to the present invention;
FIG. 7 illustrates an enhanced method of right angle hole filling according to the present invention;
FIG. 8 illustrates an enhancement method for filling a Chinese character Tian-shaped hole according to the present invention;
fig. 9 is an effect diagram of a geometric correction method of a 3D printed model.
In the figure:
pixel that indicates a hole filling has occurred>
Indicates a pixel whose state value is set to 0 in the initial model, and □ indicates that the state does not changeThe pixel of (2).
Detailed Description
The technical solutions in the implementation of the present invention will be made clear and fully described below with reference to the accompanying drawings, and the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
As shown in fig. 1, a method for geometry correction of a 3D printing model according to an embodiment of the present invention includes the following steps:
step one, constructing an initial Model (Original Model):
firstly, slicing an input grid model to obtain a plurality of sliced layers, wherein the thickness of each sliced layer is equal to the thickness of a printing layer of a 3D printer; then converting each layer of slices into a pixel model, wherein each pixel unit in each pixel model is a square, and the side length L of each square is the resolution of the 3D printer; each pixel element has a corresponding State value origi _ State, where origi _ State =1 indicates that the powder material of the pixel element needs to be sintered, and origi _ State =0 indicates that the pixel element does not need to be sintered; all pixels with State value initial _ State of 1 in all sliced layers jointly form a 3D printing model, and all pixel models jointly form an initial model.
Step two, constructing a simulation Model (Simulated Model):
the hole filling and detail missing phenomenon in the 3D printing process is simulated by using a low-pass filter, namely, an average filter with the kernel size of N multiplied by N is applied to each pixel model of an initial model, N represents the number of pixels forming the side length of the kernel to obtain a simulation model, each pixel unit of each pixel model in the simulation model also has a corresponding State value of simulate _ State, simulate _ State =1 represents that the powder material of the pixel unit needs to be sintered, and simulate _ State =0 represents that the pixel unit does not need to be sintered.
Of these, the determination of the size of the inner core is critical, and the primary factor affecting the size of the inner core is the nature of the powder material. The invention can determine the size of the kernel by adopting an experimental method. A test pattern as shown in FIG. 3 was produced, which had 10 slits, the width of the slit at the leftmost end was 0.1mm, the width of the slit at the rightmost end was 1.0mm, and the widths of the remaining slits were gradually increased from left to right. Printing the test model by using a 3D printing device, and sequentially searching for a first invisible slit from right to left to obtain a width W, thereby determining that the size of the kernel is N = W/2L. Wherein L represents a resolution size of the 3D printer; w is the maximum width of the seam that disappears after the void filling phenomenon has occurred, and when the 3D printing effect of the test model is as shown in fig. 4, W =0.5mm and n is rounded.
Step three, constructing a Difference Model (Difference Model):
subtracting the initial model from the simulation model to obtain a difference model, namely subtracting a corresponding pixel State value origin _ State from each pixel State value simulate _ State of each pixel model in the simulation model, namely subtracting a value DIF = simulate _ State-origin _ State of each pixel in the difference model, wherein the value of DIF is-1,0 or 1; DIF = -1 indicates that the pixel has a detail loss phenomenon, DIF =1 indicates that the pixel has a hole filling phenomenon, and DIF =0 indicates that the pixel has no change.
Step four, constructing an Enhanced Model:
processing pixels with hole filling phenomena according to the difference model, and then processing pixels with detail loss phenomena; and (5) carrying out hole filling processing and detail missing processing on the initial model to obtain an enhanced model. The enhanced model, like the initial model, also has several sliced layers, each sliced layer being a pixel model.
The processing method of the pixel with the hole filling phenomenon comprises the following steps:
s1, as shown in fig. 5, assuming that a pixel with a hole filling phenomenon is P, numbering the pixel P and eight neighboring pixels thereof: #1: (X-1,Y-1), #2: (X-1,Y), #3: (X-1, Y + 1), #4: (X, Y-1), #5: (X, Y), #6: (X, Y + 1), #7: (X +1,Y-1), #8: (X +1,Y), #9: (X +1, Y + 1); wherein pixel P is numbered #5; (X, Y) represents the coordinates of the pixel P;
s2, when the hole filling phenomenon occurs to three or more adjacent pixels in the #1- #9, setting the State value original _ State of the corresponding pixel to be 0 in the initial model according to different hole filling modes.
Specifically, the hole filling forms are linear, right-angle and field-shaped, and as shown in fig. 6, 7 and 8, eight neighborhood pixels of a pixel P are used as a processing unit of the pixel P;
when the hole filling form is linear, two connecting lines in a processing unit of the pixel P (namely eight neighborhood pixels of the pixel P, the same below) pass through the pixel P in the initial model, and the State value original _ State of the pixel which is vertically intersected with the linear type is set to be 0; as shown in FIG. 6, there are two types of linear hole filling; if the hole filling phenomenon occurs in the pixels # 4, #5 and #6, the State values original _ State of the pixels # 2 and #8 are set to 0 in the initial model; if the hole filling phenomenon occurs in the pixels # 2, #5 and #8, the State values original _ State of the pixels # 4 and #6 are set to 0 in the initial model;
when the hole filling form is a right-angle type, setting the State value origi _ State of a pixel which can form a complete Chinese character field with the right-angle type in one processing unit of the pixel P to be 0 in the initial model; as shown in fig. 7, twelve types of right-angle holes are filled; if the hole filling phenomenon occurs to the pixels # 2, #4 and #5, setting the State value original _ State of the pixel # 1 to 0 in the initial model; if the hole filling phenomenon occurs in the #1, #2, and #5 pixels, the State value initial _ State of the #4 pixel is set to 0 in the initial model; if the hole filling phenomenon occurs in the #1, #4, and #5 pixels, the State value initial _ State of the #2 pixel is set to 0 in the initial model; if the hole filling phenomenon occurs in the #2, #5, and #6 pixels, the State value initial _ State of the #3 pixel is set to 0 in the initial model; .... And so on;
when the hole filling form is a shape of a Chinese character tian, setting the State values original _ State of two pixels adjacent to the pixel P and outside the shape of the Chinese character tian in the processing unit of the pixel P to be 0 in the initial model; as shown in fig. 8, four filling patterns are provided for the rectangular holes; if the hole filling phenomenon occurs in the #1, #2, #4, #5 pixels, the State values original _ State of the #6, #8 pixels are set to 0 in the initial model; if the hole filling phenomenon occurs in the #2, #3, #5, #6 pixels, the State values original _ State of the #4, #8 pixels are set to 0 in the initial model; if the hole filling phenomenon occurs to the pixels # 4, #5, #7 and #8, setting the State values original _ State of the pixels # 2 and #6 to 0 in the initial model; if the hole filling phenomenon occurs in the #5, #6, #8, #9 pixels, the State values original _ State of the #2, #4 pixels are set to 0 in the initial model.
The processing mode of the pixels with the detail missing phenomenon is similar to that of the pixels with the hole filling phenomenon, the pixels are numbered first and then subjected to enhancement processing, and the form of the detail missing phenomenon is consistent with that of the hole filling phenomenon and is also divided into a linear type, a right-angle type and a field type. The only difference is that when the detail loss phenomenon occurs to three or more consecutive adjacent pixels in #1- #9, the State value origi _ State of the corresponding pixel is set to 1 instead of 0 in the initial model according to different forms of detail loss. If the shape of the missing detail is a straight line type, two connecting lines in the processing unit of the pixel P (namely eight pixels adjacent to the pixel P) are connected to the pixel P in the initial model, and the State value origi _ State of the pixel vertically intersected with the straight line type is set to be 1; when the form of the detail loss is a right-angle form, setting the State value initial _ State of a pixel which can form a complete field shape together with the right-angle form in a processing unit of the pixel P (namely eight neighborhood pixels of the pixel P) to be 1 in the initial model; when the form of the missing details is a shape of a Chinese character 'tian', the State values original _ State of two pixels adjacent to the pixel P and outside the shape of the Chinese character 'tian' in the processing unit of the pixel P are set to 1 in the initial model. Specific examples are similar to the above-mentioned processing of pixels with hole filling phenomena, and are not described in detail herein.
Step five, reconstructing a grid Model (Mesh Model):
sequentially overlapping all slice layers (namely pixel layers) in the enhanced model to obtain a voxel model; and reconstructing the voxel model into a grid model by using a Marching Cubes algorithm proposed by Lorensen and Cline as an input model of the 3D printing software.
The specific steps of reconstructing the voxel model into the grid model by using the Marching Cubes algorithm are as follows: processing each voxel in the voxel model one by one, solving the voxel intersected with the isosurface, and calculating the intersection point of the isosurface and the voxel edge by adopting a linear interpolation method; connecting the intersection points according to the relative position relation between each vertex in the voxel and the isosurface to obtain one or more triangular surface patches, wherein all the triangular surface patches form a grid model; where an iso-surface is a set of all points in space with some same value, it can be expressed as { (x, y, z) | f (x, y, z) = c }, where (x, y, z) represents the vertex coordinates of the voxel, f (x, y, z) represents the data value of the vertex, and c represents a given threshold.
As shown in fig. 9, (a) in fig. 9 is an initial model, (b) in fig. 9 is a schematic diagram when the initial model is directly used for 3D printing as an input model, (c) in fig. 9 is a difference model between (b) in fig. 9 and (a) in fig. 9, (D) in fig. 9 is an enhanced model obtained after being modified by the modification method of the present invention, (e) in fig. 9 is a schematic diagram when the enhanced model in (D) in fig. 9 is used for 3D printing as an input model, and (f) in fig. 9 is a difference model between (e) in fig. 9 and (D) in fig. 9. It can be seen that hole filling and loss of detail occur if the initial model is used directly for 3D printing. After the geometric correction of the invention is carried out on the input model, the damage or the missing phenomenon of the detail characteristics of the product can be reduced to a certain extent, and the precision and the quality of the product are improved.
In conclusion, the invention aims at the phenomena of hole filling and detail missing caused by the diffusion effect of the binder in the 3D printing process, adopts the low-pass filter to simulate the selective laser sintering process, can find out the parts with the hole filling and the detail missing, automatically carries out geometric correction on the parts without manual intervention, reduces the phenomena of damage or missing of the detail characteristics of the product to a certain extent, and improves the precision and the quality of the product. The method can offset the influence of the diffusion effect of the binder on the product precision, so that the geometric detail characteristics of the product damaged or completely lost in the 3D printing process can be seen again, and the product quality is improved.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Furthermore, it should be understood that although the specification describes embodiments, not every embodiment includes only a single embodiment, and such description is for clarity purposes only, and it will be understood by those skilled in the art that the specification as a whole and the embodiments may be combined as appropriate to form other embodiments as would be understood by those skilled in the art.
Claims (5)
1. A geometric correction method for a 3D printing model is characterized by comprising the following steps:
step one, constructing an initial model:
firstly, slicing an input grid model to obtain a plurality of sliced layers, wherein the thickness of each sliced layer is equal to the thickness of a printing layer of a 3D printer; then converting each layer of slices into pixel models, wherein each pixel unit in each pixel model is a square, and the side length L of each square is the resolution of the 3D printer; each pixel cell has a corresponding State value, original _ State =1 indicating that the powder material of the pixel cell needs to be sintered, original _ State =0 indicating that the pixel cell does not need to be sintered; all pixels with the State value initial _ State of 1 in all the sliced layers form a 3D printing model together;
step two, constructing a simulation model:
simulating the hole filling and detail missing phenomena in the 3D printing process by using a low-pass filter, namely applying an average filter with the kernel size of NxN to each pixel model of an initial model, wherein N represents the number of pixels forming the side length of the kernel to obtain a simulation model, each pixel unit of each pixel model in the simulation model also has a corresponding State value of simulate _ State, simulate _ State =1 represents that the powder material of the pixel unit needs to be sintered, and simulate _ State =0 represents that the pixel unit does not need to be sintered;
step three, constructing a difference model:
subtracting the initial model from the simulation model to obtain a difference model, namely subtracting a corresponding pixel State value original _ State in the initial model from each pixel State value simulate _ State of the simulation model, namely, the value DIF = simulate _ State-original _ State of each pixel in the difference model, and the value DIF is-1,0 or 1; DIF = -1 indicates that a detail loss phenomenon occurs, DIF =1 indicates that a hole filling phenomenon occurs, and DIF =0 indicates that there is no change;
step four, constructing an enhanced model:
processing the pixels with the hole filling phenomenon according to the difference model, and then processing the pixels with the detail loss phenomenon; carrying out hole filling processing and detail missing processing on the initial model to obtain an enhanced model;
step five, reconstructing a grid model:
sequentially overlapping all slice layers in the enhanced model to obtain a voxel model; and reconstructing the voxel model into a grid model by using a Marching Cubes algorithm as an input model of the 3D printing software.
2. A method for geometry correction of a 3D printed model according to claim 1, characterized in that in the second step, the kernel size N = W/2L; wherein L is the resolution of the 3D printer, W is the maximum width of the invisible slit after the hole filling phenomenon occurs, and N is rounded.
3. A method for geometry modification of a 3D printed model according to claim 1 or 2, wherein the pixels with hole filling in the fourth step are processed by:
s1, numbering a pixel P and eight neighborhood pixels of the pixel P, wherein the pixel P is P in which a hole filling phenomenon occurs: #1: (X-1,Y-1), #2: (X-1,Y), #3: (X-1, Y + 1), #4: (X, Y-1), #5: (X, Y), #6: (X, Y + 1), #7: (X +1,Y-1), #8: (X +1,Y), #9: (X +1, Y + 1); wherein pixel P is numbered #5; (X, Y) represents the coordinates of the pixel P;
s2, when three or more adjacent pixels in the #1- #9 generate hole filling phenomena, setting the State value original _ State of the corresponding pixel to be 0 in the initial model according to different hole filling forms;
the processing manner of the pixels with the missing-in-detail phenomenon in the fourth step is similar to that of the pixels with the hole filling phenomenon, except that when the missing-in-detail phenomenon occurs to three or more consecutive adjacent pixels in #1- #9, the State value original _ State of the corresponding pixel is set to 1 in the initial model according to different forms of the missing-in-detail.
4. The method of claim 3, wherein the filling pattern of the holes and the pattern of the missing details are linear, rectangular and rectangular,
when the hole filling form is a linear type, connecting a line through a pixel P in the initial model, and setting the State value original _ State of two pixels which are vertically intersected with the linear type to be 0;
when the hole filling form is a right-angle form, setting the State value origi _ State of one pixel which can form a complete Chinese character 'tian' with the right-angle form as 0 in the initial model;
when the hole filling form is a shape of Chinese character 'tian', setting the State values original _ State of two pixels adjacent to the pixel P and outside the shape of Chinese character 'tian' to 0 in the initial model;
when the form of the detail loss is linear type, connecting a line through a pixel P in the initial model, and setting the State value original _ State of two pixels which are vertically intersected with the linear type as 1;
when the form of detail loss is a right-angle form, setting the State value origi _ State of a pixel which can form a complete field with the right-angle form to 1 in the initial model;
when the form of the missing detail is a shape of a Chinese character 'tian', the State values origi _ State of two pixels adjacent to the pixel P and outside the shape of the Chinese character 'tian' are set to 1 in the initial model.
5. The method for geometry correction of 3D printing model according to claim 4, wherein the concrete steps of reconstructing the voxel model into the mesh model by using Marching Cubes algorithm in the fifth step are as follows: processing each voxel in the voxel model one by one, solving the voxel intersected with the isosurface, and calculating the intersection point of the isosurface and the voxel edge by adopting a linear interpolation method; connecting the intersection points according to the relative position relation between each vertex in the voxel and the isosurface to obtain one or more triangular surface patches, wherein all the triangular surface patches form a grid model; where an iso-surface is a set of all points in space with some same value, denoted as { (x, y, z) | f (x, y, z) = c }, where (x, y, z) represents the vertex coordinates of the voxel, f (x, y, z) represents the data value of the vertex, and c represents a given threshold.
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| CN103617603A (en) * | 2013-12-06 | 2014-03-05 | 南京大学 | Automatic restoration method of three-dimensional digital geometric grid model structure |
| CN105616036A (en) * | 2015-12-23 | 2016-06-01 | 南京航空航天大学 | Direct entity 3D printing method based on medical cross-sectional images |
| CN109410334A (en) * | 2018-09-21 | 2019-03-01 | 桂林电子科技大学 | A kind of three-dimensional grid model defect hole restorative procedure based on characteristic curve |
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