CN113313747A - STL format-based three-dimensional model support point acquisition method - Google Patents

STL format-based three-dimensional model support point acquisition method Download PDF

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CN113313747A
CN113313747A CN202110575226.4A CN202110575226A CN113313747A CN 113313747 A CN113313747 A CN 113313747A CN 202110575226 A CN202110575226 A CN 202110575226A CN 113313747 A CN113313747 A CN 113313747A
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point
points
support point
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CN113313747B (en
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李祥友
贺兵
王泽敏
兰新强
李树寒
李桐
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Huazhong University of Science and Technology
Ezhou Institute of Industrial Technology Huazhong University of Science and Technology
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Ezhou Institute of Industrial Technology Huazhong University of Science and Technology
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Abstract

The invention relates to the technical field of 3D printing, in particular to a method for acquiring a three-dimensional model supporting point based on an STL format. Which comprises the following steps: rapidly identifying overhanging areas needing to be added with support in the three-dimensional model in the STL format; determining candidate support points according to the overhanging region, the horizontal projection region and the layering thickness element; clustering all the candidate support points, taking the clustered cluster center coordinate point as a support point, and extracting the support point; constructing a support center line according to the interference condition between the radiation area of the support point and the model; and all the support center lines construct the STL-format support structure according to the three-dimensional model rule. The invention can effectively avoid the defect that the overhanging region lacks support points, all the support points come from candidate support points, and can effectively reduce the number of the support points, thereby shortening the post-processing time of support, reducing the residual amount of the support points, eliminating redundant support points and achieving the aim of indirectly improving the surface quality of products.

Description

STL format-based three-dimensional model support point acquisition method
Technical Field
The invention relates to the technical field of 3D printing, in particular to a method for acquiring a three-dimensional model supporting point based on an STL format.
Background
The support point is the central coordinate point of the contact area between the support structure and the model entity. The support structure is used as a key part of the support structure, and is directly related to whether auxiliary materials can be smoothly stacked and formed in the 3D printing process of the support structure. The reasonably deployed support points can not only ensure that all the overhanging surfaces (of the model entity) can be assisted by the support structure, but also avoid the redundancy of the support structure;
however, the current mainstream method for acquiring the support points is to extract the support points from the relevant regions of the overhanging elements. The support points acquired by the method are coordinate points (generally central coordinate points of the grid) extracted from the projection area grid of the overhanging area in the XOY plane, so that the support points acquired by the method have position and number deviations from the actually required support points; the method for acquiring the support points instead of the main flow extracts the support points from the difference region between the layered contours, and the calculation amount of the method is in positive correlation with the layer thickness, the height and the precision of the model. Under the condition of partial large models, high-precision models or fine layering, the method has the obvious defects of overlong waiting time, overlarge memory consumption and the like, and in view of the defects, the method for acquiring the three-dimensional model supporting points based on the STL format is provided.
Disclosure of Invention
The invention aims to provide a method for acquiring a three-dimensional model supporting point based on an STL format, so as to solve the problems in the background technology.
In order to achieve the above object, the present invention provides a method for obtaining support points of a three-dimensional model based on STL format, comprising the following steps:
identifying overhanging regions of the three-dimensional model in the STL format which need to be supported;
determining candidate support points according to the overhanging region, the horizontal projection region of the overhanging region and the layering thickness element of the overhanging region;
clustering all the candidate support points, taking the clustered cluster center coordinate point as a support point, and extracting the support point;
constructing a support central line according to the extracted interference condition between the radiation area of the support point and the model;
and constructing the support structure body in the STL format according to all the support center lines and the three-dimensional model rule.
As a further improvement of the present technical solution, the basic elements of the overhanging region include:
a suspension triangular patch, which is a triangular patch for rapidly extracting Z components Fz of all normal vectors from the model in a multithreading mode, wherein the Z components Fz are not less than eta (-1 is not more than eta and not more than-0.5);
the suspension wire, according to relevant characteristic draws corresponding suspension wire in the model fast, and suspension wire needs satisfy three conditions simultaneously:
the vector delta of the suspension line in the Z-axis negative direction is less than or equal to eta;
fz of all triangular surface patches (the suspension line is one line segment) is more than eta;
fz of at least one triangular patch (the suspension wire is one line segment) is less than 0;
the suspension point is extracted from the model according to the relevant characteristics, and the suspension point also needs to satisfy three conditions:
fz of a triangular patch (a suspension point is one of coordinate points) is larger than eta;
the coordinate point with the lowest Z component in all triangular patches (the suspension point is one of the coordinate points of the triangular patches);
a line segment formed by any coordinate point in the triangular patch and the suspension point does not meet the requirement of the suspension line;
after the three basic elements are extracted, all the discrete overhanging triangular patches are combined according to a common edge relationship to form an overhanging region. Through the technical scheme, a link of quickly extracting the characteristic elements is reserved, and a step of accurately extracting the support points in the layer polygon difference region is combined. Therefore, the method has the advantages of high operation efficiency, low memory consumption, high positioning accuracy and the like.
As a further improvement of the present technical solution, the determining the candidate support point includes the following steps:
performing intersection operation on each suspension area, each suspension line and the set layering thickness (0.05-0.5mm) to obtain ordered three-dimensional contour points;
projecting the corresponding overhanging region to an XOY horizontal plane, wherein the projection region is divided into a plurality of sub-projection regions according to the interval of 2-20 mm;
then, more than one three-dimensional contour point is ensured to be present in the stereo space of each sub-projection area as candidate support points; if only one three-dimensional contour point exists in the stereo space of the sub-projection area, the three-dimensional contour point is a candidate support point; if the three-dimensional contour point does not exist in the stereoscopic space of the sub-projection area, the coordinate point of the center coordinate of the sub-projection area mapped to the overhanging area is a candidate support point; if more than one three-dimensional contour point exists in the three-dimensional space of the sub-projection area, eliminating the initial coordinate point with the line segment length less than 0.5mm in the three-dimensional contour points of the same layer; removing the middle three-dimensional contour points with the included angle theta of more than or equal to 150 degrees between adjacent line segments of the same layer; all the remaining three-dimensional contour points are candidate support points.
Therefore, the support points are assisted in all the key positions of the overhanging areas, and the defect that the overhanging areas lack the support points can be effectively avoided.
As a further improvement of the present technical solution, the extracting the support point includes the steps of:
dividing all candidate support points in the independent overhanging region into a plurality of clusters according to the maximum radius (0.5-5mm) and the minimum distance (1-10mm) of the clusters;
clustering all candidate support points by adopting a clustering algorithm, wherein the clustering algorithm can divide the candidate support points with similar three-dimensional space coordinates into the same cluster and comprises a K-Means algorithm, a K-medoids algorithm, a K-modes algorithm, a K-Means algorithm and a kernelk-Means algorithm;
after clustering is finished, the nearest candidate support point close to the cluster center is used as a support point, and the distance between the farthest candidate support points in the cluster is used as the diameter of the support point;
all the support points are from the candidate support points, i.e. no redundant support points are generated. Therefore, the number of supporting points can be effectively reduced, thereby shortening the time for supporting the post-process and reducing the residual amount of the supporting points. Meanwhile, redundant supporting points are eliminated, and the surface quality of the product is indirectly improved.
As a further improvement of the technical solution, the clustering algorithm includes the following steps:
randomly selecting k data objects, each data object representing a cluster center, i.e. selecting k initial centers;
assigning all the remaining candidate support points to the cluster corresponding to the most similar cluster center according to the similarity between the candidate support points and the cluster centers;
then, the average value of all objects in each cluster is recalculated and used as a new cluster center;
this process is repeated until no significant change in cluster center occurs.
As a further improvement of the technical solution, the support center line is constructed by using a tree-shaped branch connection rule, the tree-shaped branch connection rule is used for realizing that the center line segment of the tree-shaped support is derived from the support point, and other support types such as grid, outline, block, line, point, rib, comprehensive, cone and the like can be selected.
As a further improvement of the technical solution, the tree-like branch connection rule comprises the following steps:
sequencing all the supporting points from high to low according to the z component of the coordinate to obtain an ordered supporting point linked list;
performing interference processing between every two support points in the linked list to obtain a new support point with the maximum interference distance;
support point P1And the supporting points Pi meeting the conditions are removed from the supporting point linked list, and the intersection point coordinates are inserted into the supporting point linked list;
support point P1Removing from the chain table of supporting points and extracting the next supporting point P2Instead of the above-mentioned support point P1The same operation as described above is performed. And so on until the list of support points is empty.
As a further improvement of the present technical solution, the interference processing includes the steps of:
extracting a first support point P from a linked list1And each subsequent support point Pi(i is 2, 3 …) making downward 5-60 degree conical radiation in the plane formed by the projection points in the XOY plane, and obtaining the intersection point coordinate P;
if the z-component of the support point P is less than or equal to 0, the support point P is considered1To another supporting point PiThe support centerline cannot be derived. At this time, the next support point P is extractedi+1And P1And performing interference treatment. Analogizing in sequence until no supporting point in the linked list can be extracted;
if the z-component of the support point P is greater than 0, the support point P is set1And P form a line segment L1、PiAnd P form a line segment L2Pre-interference processing is carried out on the two line segments and the three-dimensional model in the STL format; if line segment L1And L2When the line segment L passes through any triangular patch in the three-dimensional model in the STL format, the line segment L is judged1And L2There is interference with the three-dimensional model in STL format, which also means P1And P2The support center line cannot be derived; otherwise, record L1、L2And the minimum distance from the two line segments to the three-dimensional model in the STL format;
p in chain table of points to be supported1With all PiAfter all the pre-interference treatment is finished; if P is1With all PiCan not derive the support center line, then P1Performing single-point radiation; single point radiationIs to mix P1And its projected point P on XOY plane1Forming a straight line to perform conical radiation at a specific angle (such as theta is 2-40 degrees); if the straight line P1And P1' there is an intersection point P with the three-dimensional model, then P1P is taken as a supporting central line; otherwise, P1P1' as a support centerline. If P is1And a plurality of PiDeriving a plurality of supporting center lines, and corresponding the shortest line segment with the distance more than or equal to 1mm between the teeth to L1And L2As a support centerline.
As a further improvement of the technical solution, the three-dimensional model rule expands the support centerline into a support structure according to the support centerline as an axis, the width of the top teeth as a radius, the support shape, the top width of the teeth, and the spacing parameters, and converts the support structure into a three-dimensional model in STL format.
Compared with the prior art, the invention has the beneficial effects that:
in the STL format-based three-dimensional model support point acquisition method, a link of quickly extracting characteristic elements is realized, and a step of accurately extracting support points in a layer polygon difference region is combined, so that the method has the advantages of high efficiency, low memory consumption, high positioning precision and the like. On the basis of ensuring that the key positions of all the overhanging areas have supporting point assistance, the defect that the overhanging areas lack supporting points can be effectively avoided. Meanwhile, all the supporting points are from the candidate supporting points, namely, redundant supporting points can not be generated, so that the number of the supporting points can be effectively reduced, the supporting post-processing time is shortened, the residual quantity of the supporting points is reduced, redundant supporting points are eliminated, and the aim of indirectly improving the surface quality of the product can be achieved.
Drawings
FIG. 1 is an overall flow chart of example 1;
FIG. 2 is a schematic diagram of the overall algorithm of embodiment 1;
FIG. 3 is a schematic diagram of a triangular patch of embodiment 1;
FIG. 4 is a schematic diagram of three types of suspension elements, i.e., a suspension triangular patch, a suspension wire and a suspension point, according to example 1;
FIG. 5 is a schematic diagram of the embodiment 1 for extracting candidate support points;
FIG. 6 is a schematic diagram of extraction of support points in example 1;
FIG. 7 is a schematic view of the construction support centerline of example 1.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
Referring to fig. 1 to 7, the present embodiment provides a method for obtaining a support point of a three-dimensional model based on an STL format, and specifically, as shown in fig. 1 to 2, the method includes the following steps:
s1, rapidly identifying an overhanging region needing to be supported in the three-dimensional model in the STL format;
s2, determining candidate supporting points according to the overhanging region, the horizontal projection region and the layering thickness element;
s3, clustering all the candidate support points, and taking the clustered cluster center coordinate point as a support point;
s4, constructing a support center line according to the interference condition between the intersection line of the radiation areas of every two support points and the model;
and S5, constructing the support structure body in the STL format according to the three-dimensional model rule by all the support center lines.
The link for rapidly extracting the feature elements in this embodiment is shown in fig. 3 to 4. The basic elements of the overhanging region include:
a hanging triangular patch: quickly extracting triangular patches with Z components Fz less than or equal to-0.5 of all normal vectors from the model in a multithreading mode;
suspension wire: and rapidly extracting the corresponding suspension line from the model according to the relevant characteristics. The suspension wire needs to satisfy the following three basic characteristics at the same time:
the vector delta of the suspension wire in the Z-axis negative direction is less than or equal to-0.5;
fz of all triangular surface patches (the suspension line is one line segment) is more than eta (-1 < eta < 0.5);
③ Fz of at least one triangular patch (the suspension line is one of the line segments) is less than eta (-1 is less than or equal to-0.5);
suspension point: and rapidly extracting the corresponding suspension point from the model according to the relevant characteristics. The suspension point also needs to satisfy three conditions:
the Fz of a triangular patch (a suspension point is one of coordinate points) is more than eta (-1 is more than eta and is less than or equal to-0.5);
the coordinate point with the lowest Z component in all triangular patches (the suspension point is one of the coordinate points of the triangular patches);
a line segment formed by any coordinate point in the triangular patch and the suspension point does not meet the requirement of the suspension line;
after the three basic elements are extracted, all discrete overhanging triangular patches are combined to form an overhanging region according to a common-edge relation, so that a link of quickly extracting the characteristic elements is realized, and the step of accurately extracting the supporting points in the layer polygon difference region is combined, so that the method has the advantages of high efficiency, low memory consumption, high positioning precision and the like.
Further, candidate support points are extracted from the overhanging region, as shown in fig. 5. Determining candidate support points comprises the steps of:
performing intersection operation on each suspension area and each suspension line and a set layering thickness (z is 0.2mm) to obtain ordered three-dimensional contour points;
projecting the overhanging region to an XOY horizontal plane, and dividing the projection region into a plurality of sub-projection regions according to a 10mm interval;
it is ensured that more than one three-dimensional contour point must exist in the volume space of each sub-projection area. If only one three-dimensional contour point exists in the stereo space of the sub-projection area, the three-dimensional contour point is a candidate support point. If no three-dimensional contour point exists in the stereo space of the sub-projection area, the coordinate point of the center coordinate of the sub-projection area mapped to the overhanging area is a candidate support point. If more than one three-dimensional contour point exists in the three-dimensional space of the sub-projection area, eliminating the initial coordinate point with the line segment length less than 0.5mm in the three-dimensional contour points of the same layer; finally, removing the middle three-dimensional contour points with the included angle theta of more than or equal to 150 degrees between adjacent line segments of the same layer; and all the remaining three-dimensional contour points are the candidate support points.
The step can ensure that all the candidate support points come from the three-dimensional contour points of the overhanging region, and effectively eliminates useless support points.
It should be noted that, in order to further eliminate redundant support points, the method employs a clustering algorithm to extract support points, as shown in fig. 6. The process of extracting the supporting points comprises the following steps:
dividing all candidate support point sets in the independent overhanging region into a plurality of clusters according to the maximum radius (0.5-5) mm and the minimum distance (1-15) mm of the clusters;
clustering all candidate support points by adopting a clustering algorithm, wherein the K-Means clustering algorithm can divide the candidate support points with similar three-dimensional space coordinates into the same cluster;
after clustering is finished, the nearest candidate support point close to the cluster center is used as a support point, and the distance between the farthest candidate support points in the cluster is used as the diameter of the support point;
all the supporting points are from the candidate supporting points, namely, redundant supporting points are not generated, so that the number of the supporting points can be effectively reduced, the time for supporting post-processing is shortened, and the residual quantity of the supporting points is reduced. Redundant supporting points are eliminated, and the purpose of improving the surface quality of the product can be achieved.
Specifically, the clustering algorithm comprises the following steps:
randomly selecting k data objects, each data object representing a cluster center, i.e. selecting k initial centers;
for each of the remaining objects, assigning it to the cluster corresponding to its most similar cluster center according to its similarity to the cluster centers;
then, the average value of all objects in each cluster is recalculated and used as a new cluster center;
this process is repeated until no significant change in cluster center occurs.
Further, as shown in fig. 7. In order to accurately determine the support center line, the support center line is constructed by adopting a tree-shaped branch connection rule, the tree-shaped branch connection rule is used for deriving a center line segment of the tree-shaped support from the support point, and other support types such as grid, outline, block, line, point, rib, comprehensive and cone can be selected.
Wherein, the tree-shaped branch connection rule comprises the following steps:
sequencing all the supporting points from high to low according to the z component of the coordinate to obtain an ordered supporting point linked list;
performing interference processing between every two support points in the linked list to obtain a new support point with the maximum interference distance;
support point P1And the supporting points Pi meeting the conditions are removed from the supporting point linked list, and the intersection point coordinates are inserted into the supporting point linked list;
support point P1Removing from the chain table of supporting points and extracting the next supporting point P2Instead of the above-mentioned support point P1The same operation is carried out until the supporting point chain table is empty, and the supporting center line is determined.
Specifically, in order to make the interference processing between every two support points more complete, the interference processing includes the following steps:
extracting a first support point P from a linked list1And each subsequent support point Pi(i is 1, 2, 3 …) making 30-degree downward conical radiation in a plane formed by projection points in an XOY plane to obtain an intersection point coordinate P;
if the z-component of the support point P is less than or equal to 0, the support point P is considered1The support center line can not be derived from the other support point Pi, and the next support point P is extractedi+1And P1Performing interference treatment, and repeating the steps until no supporting point in the linked list can be extracted;
if the component of the support point P is greater than 0, the support point P is set1And P form a line segment L1Pi and P form a line segment L2Pre-interference processing is carried out on the two line segments and the three-dimensional model in the STL format; if line segment L1And L2When the line segment L passes through any triangular patch in the three-dimensional model in the STL format, the line segment L is judged1And L2There is interference with the three-dimensional model in STL format, which also means P1And P2The support center line cannot be derived; otherwise, record L1、L2And the minimum distance from the two line segments to the three-dimensional model in the STL format;
p in chain table of points to be supported1With all PiAfter all the pre-interference treatment is finished, if P1With all PiCan not derive the support center line, then P1Performing single-point radiation; the single point of radiation is to irradiate P1And its projected point P on XOY plane1' make up the straight line and make 30 degree conical radiation; if the straight line P1And P1' there is an intersection point P with the three-dimensional model, then P1P is taken as a supporting central line; otherwise P1P1' as a support centerline; if P is1And a plurality of PiDeriving a plurality of supporting center lines, and corresponding the shortest line segment with the minimum distance more than or equal to 1mm of the interdental space to L1And L2As a support centerline.
In addition, in order to convert the support structure into a three-dimensional model in STL format, the three-dimensional model rule is to expand the support centerline into the support structure and convert the support structure into a three-dimensional model in STL format according to the support centerline as an axis, the width of the top teeth as a radius, the support shape, the width of the top of the teeth, and the pitch parameters.
The foregoing shows and describes the general principles, essential features, and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and the preferred embodiments of the present invention are described in the above embodiments and the description, and are not intended to limit the present invention. The scope of the invention is defined by the appended claims and equivalents thereof.

Claims (9)

1. A three-dimensional model support point obtaining method based on STL format is characterized by comprising the following steps:
identifying overhanging regions of the three-dimensional model in the STL format which need to be supported;
determining candidate support points according to the overhanging region, the horizontal projection region of the overhanging region and the layering thickness element of the overhanging region;
clustering all the candidate support points, taking the clustered cluster center coordinate point as a support point, and extracting the support point;
constructing a support central line according to the extracted interference condition between the radiation area of the support point and the model;
and constructing the support structure body in the STL format according to all the support center lines and the three-dimensional model rule.
2. The STL format-based three-dimensional model support point acquisition method according to claim 1, wherein: the basic elements of the overhanging region include:
the suspended triangular patch is used for quickly extracting the triangular patches of which the Z components Fz of all normal vectors are less than or equal to eta from the model in a multithreading mode, wherein eta is more than or equal to-1 and less than or equal to-0.5;
the suspension wires are used for rapidly extracting corresponding suspension wires from the model according to the relevant characteristics;
and (4) hanging points, namely quickly extracting corresponding hanging points from the model according to the relevant characteristics.
3. The STL format-based three-dimensional model support point acquisition method according to claim 1, wherein: the determining candidate support points comprises the following steps:
performing intersection operation on each suspension area and each suspension line and the set layered thickness to obtain ordered three-dimensional contour points;
projecting the overhanging region to an XOY horizontal plane, and dividing the projection region into a plurality of sub-projection regions according to the interval of 2-20 mm;
ensuring that more than one three-dimensional contour point must exist in the stereo space of each sub-projection area; if only one three-dimensional contour point exists in the stereo space of the sub-projection area, the three-dimensional contour point is a candidate support point; if the three-dimensional contour point does not exist in the stereoscopic space of the sub-projection area, the coordinate point of the center coordinate of the sub-projection area mapped to the overhanging area is a candidate support point; if more than one three-dimensional contour point exists in the three-dimensional space of the sub-projection area, the initial coordinate points with the line length being less than 0.5mm in the three-dimensional contour points of the same layer are removed, the middle three-dimensional contour points with the included angle theta being more than or equal to 150 degrees between the adjacent line segments of the same layer are removed, and the remaining three-dimensional contour points after removal are the candidate support points.
4. The STL format-based three-dimensional model support point acquisition method according to claim 1, wherein: the extraction of the support points comprises the following steps:
dividing all candidate support point sets in the independent overhang area into a plurality of clusters according to the maximum radius and the minimum distance of the clusters, wherein the maximum radius is 0.5-5mm, and the minimum distance is 1-15 mm;
clustering all candidate support points by adopting a clustering algorithm, wherein the clustering algorithm can divide the candidate support points with similar three-dimensional space coordinates into the same cluster, and the clustering algorithm comprises one of a K-Means algorithm, a K-medoids algorithm, a K-modes algorithm, a K-Means algorithm and a kernelk-Means algorithm;
after clustering is finished, the nearest candidate supporting point close to the cluster center is used as a supporting point, and the distance between the farthest candidate supporting points in the cluster is used as the diameter of the supporting point.
5. The STL format-based three-dimensional model support point acquisition method according to claim 1, wherein: the clustering algorithm comprises the following steps:
randomly selecting k data objects, each data object representing a cluster center, i.e. selecting k initial centers;
for each of the remaining objects, assigning it to the cluster corresponding to its most similar cluster center according to its similarity to the cluster centers;
then, the average value of all objects in each cluster is recalculated and used as a new cluster center;
this process is repeated until no significant change in cluster center occurs.
6. The STL format-based three-dimensional model support point acquisition method according to claim 1, wherein: the support center line is constructed by adopting a tree-shaped branch connection rule, and the tree-shaped branch connection rule is used for realizing that the center line segment of the tree-shaped support is derived from the support points.
7. The STL format-based three-dimensional model support point acquisition method according to claim 6, wherein: the tree-shaped branch connection method comprises the following steps:
sequencing all the supporting points from high to low according to the z component of the coordinate to obtain an ordered supporting point linked list;
performing interference processing between every two support points in the linked list to obtain a new support point with the maximum interference distance;
support point P1And a support point P satisfying the conditioniRemoving from the supporting point linked list, and inserting the intersection point coordinates into the supporting point linked list;
support point P1Removing from the chain table of supporting points and extracting the next supporting point P2Instead of the above-mentioned support point P1The same operation is carried out until the supporting point chain table is empty, and the supporting center line is determined.
8. The STL format-based three-dimensional model support point acquisition method of claim 7, wherein: the interference treatment comprises the following steps:
extracting a first support point P from a linked list1And each subsequent support point PiConical radiation with an angle of 5-60 degrees is performed downwards in a plane formed by projection points in the XOY plane to obtain a coordinate P of an intersection point;
if the z-component of the support point P is less than or equal to 0, the support point P is considered1To another supporting point PiThe support centerline cannot be derived, thereby extracting the next support point Pi+1And P1Performing interference processing, and repeating the steps until no candidate support point in the linked list can be extracted;
if the z-component of the support point P is greater than 0, the support point P is set1And P form a line segment L1、PiAnd P form a line segment L2Pre-interference processing is carried out on the two line segments and the three-dimensional model in the STL format, PiIn the formula, i is an integer.
9. The STL format-based three-dimensional model support point acquisition method according to claim 1, wherein: the three-dimensional model rule expands the support center line into a support structure according to the support center line as an axis, the top tooth width as a radius, the support shape, the top width of the teeth and the spacing parameters, and converts the support structure into the STL-format three-dimensional model.
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