Build path optimization using grouped trianges of a polygonal mesh

Abstract

The strength of a bond between two adjacent layers of a three-dimensional print is weakened by initiating fabrication of a top layer at a height greater than the processing height for the print. This technique may be used in particular at the interface between a raft or other support and an object being fabricated, after which the printing process may return to a regular process height for additional layers used to fabricate the remainder of the object.

1 - 20 . (canceled) 
     
     
         21 . A method for generating extrusion paths to fabricate an object based on a three-dimensional model, the method comprising:
 parsing the three-dimensional model to extract a plurality of triangle coordinates, the plurality of triangle coordinates forming a plurality of triangles that characterize an exterior surface of the three-dimensional model;   grouping the plurality of triangles according to a plurality of layers, wherein each of the plurality of layers is a fabrication layer at a processing height step within a build volume of a three-dimensional printer, and wherein each of the plurality of layers nonexclusively contains one or more of the plurality of triangles intersecting the one of the plurality of layers at the processing height step, thereby providing a group of triangles for each of the plurality of layers within the build volume;   for each layer of the plurality of layers containing at least one triangle:
 selecting a corresponding group of triangles, 
 identifying line segments where each triangle in the corresponding group of triangles intersects a plane of the layer, 
 combining the line segments into one or more loops for the layer, and 
 processing each of the one or more loops into a printable path for a portion of the object within that one of the plurality of layers; and 
   combining the printable path for the object in each one of the plurality of layers to form an extrusion path for fabricating the object within the build volume.   
     
     
         22 . The method of  claim 21 , wherein processing each of the one or more loops for one of the layers includes removing portions of each of the one or more loops having a size below a predetermined threshold set by printing capabilities of a three-dimensional printer, thereby forming a processed outline for the layer, and creating an extrusion path for an object in the layer at least partially formed by the processed outline. 
     
     
         23 . The method of  claim 22 , further comprising:
 classifying one or more regions based on a location within the processed outline;   optimizing extrusion paths based on classification of the one or more regions;   converting the optimized extrusion paths into machine-ready commands interpretable by a controller of the three-dimensional printer; and   building a three-dimensional object based on the machine-ready commands using the three-dimensional printer.   
     
     
         24 . The method of  claim 23 , wherein the one or more regions include at least one of an inset, a roof, a floor, infill, a support, and a raft. 
     
     
         25 . The method of  claim 23 , wherein optimization includes identifying an open path from an end vertex of a first path to a start vertex of a second path, and including the open path in the optimized extrusion paths. 
     
     
         26 . The method of  claim 23 , wherein optimization includes removing redundant vertices between paths and redundant connections between vertices. 
     
     
         27 . The method of  claim 21 , wherein processing each of the one or more loops includes removing detail that is smaller than a print resolution of the three-dimensional printer. 
     
     
         28 . The method of  claim 21 , wherein processing each of the one or more loops includes restoring a continuity of a surface of the object within the plane of the layer. 
     
     
         29 . The method of  claim 21 , wherein processing each of the one or more loops includes repairing a non-manifold portion of at least one of the one or more loops. 
     
     
         30 . The method of  claim 21 , wherein processing each of the one or more loops includes smoothing the printable path within the plane of the layer. 
     
     
         31 . The method of  claim 21 , wherein processing each of the one or more loops includes identifying at least one curve in the printable path and applying a linear filter to compute a dynamic velocity along the at least one curve. 
     
     
         32 . The method of  claim 21 , wherein processing each of the one or more loops includes identifying at least one curve in the printable path and lowering a print speed for the printable path when the at least one curve has a radius of curvature within a predetermined range. 
     
     
         33 . The method of  claim 21 , wherein the three-dimensional model includes at least one of a stereolithography (STL) file and a computer aided design (CAD) file. 
     
     
         34 . The method of  claim 21 , wherein the three-dimensional model includes at least one of: output from a scanner, output from a three-dimensional modeling program, and a selection from a database of three-dimensional models. 
     
     
         35 . The method of  claim 21 , further comprising storing the plurality of triangle coordinates in an array. 
     
     
         36 . The method of  claim 21 , wherein an order of a set of three triangle coordinates for each of the plurality of triangles defines a face directed toward an interior of the three-dimensional model. 
     
     
         37 . The method of  claim 21 , wherein processing each of the one or more loops includes combining collinear portions within a certain error threshold. 
     
     
         38 . A computer program product for generating extrusion paths to fabricate an object based on a three-dimensional model, the computer program product comprising non-transitory computer executable code embodied in a non-transitory computer-readable medium that, when executing on one or more computing devices, performs the steps of:
 parsing the three-dimensional model to extract a plurality of triangle coordinates forming a plurality of triangles that characterizing an exterior surface of the three-dimensional model;   grouping the plurality of triangles according to a plurality of layers, wherein each of the plurality of layers is a fabrication layer for the object, and wherein each of the plurality of layers nonexclusively contains one or more of the plurality of triangles intersecting the one of the plurality of layers, thereby providing a group of triangles for each of the fabrication layers;   for each layer containing one or more of the triangles:
 selecting a corresponding group of triangles for the layer, 
 identifying line segments where each triangle in the corresponding group of triangles intersects the layer, 
 combining the line segments into one or more loops for the layer, and 
 processing each of the one or more loops into a printable path for a portion of the object; and 
   combining the printable path for the object in each layer to form an extrusion path for fabricating the object with a three-dimensional printer.   
     
     
         39 . The computer program product of  claim 38 , wherein processing each of the one or more loops includes removing portions of each of the one or more loops having a size below a predetermined threshold set by printing capabilities of a three-dimensional printer, thereby forming a processed outline for the layer, and creating an extrusion path for an object in the layer at least partially formed by the processed outline. 
     
     
         40 . A system comprising:
 a three-dimensional printer having an extruder; and   processing circuitry associated with the three-dimensional printer and configured by computer executable code to perform the steps of:
 receiving a three-dimensional model of an object; 
 parsing the three-dimensional model to extract a plurality of triangle coordinates forming a plurality of triangles that characterizing an exterior surface of the three-dimensional model; 
 grouping the plurality of triangles according to a plurality of layers, wherein each of the plurality of layers is a fabrication layer for the object, and wherein each of the plurality of layers nonexclusively contains one or more of the plurality of triangles intersecting the one of the plurality of layers, thereby providing a group of triangles for each of the fabrication layers; 
 for each layer containing one or more of the triangles: 
 selecting a corresponding group of triangles for the layer, 
 identifying line segments where each triangle in the corresponding group of triangles intersects the layer, 
 combining the line segments into one or more loops for the layer, and 
 processing each of the one or more loops into a printable path for a portion of the object; and 
 
 combining the printable path for the object in each layer to form an extrusion path for fabricating the object with a three-dimensional printer.