On The Supporting Structure Generation Algorithm In 3D Printing Of Ancient Architecture

Ancient architecture is a valuable product left by mankind for thousands of years.The restoration and protection of the ancient building heritage are a necessary and difficult work.The use of 3D printing technology not only can minimize the cost,but also achieve realistic restoration.However,in the 3D process,in the case of unsupported,melt collapse occurs for the area of the internal and external floating area of the ancient buildings.Some support structure generation algorithms generate the same support structure for the internal and external floating area.At the same time,there exit many problems,such as time consuming,support instability,and much material used etc.In view of the above shortcomings,In this paper,the main content of the study is to identify the supporting area of the ancient building,the area to be supported,the optimization of the support structure generation algorithm,Specific research works are as follows:Firstly,identify the suspension area to be supported of the ancient building.For the STL format of the ancient building model,the author uses topology reconstruction algorithm to make the triangular patches relate to each other orderly and draws the contours of the cross-section.Besides,internal and external contour automatic recognition technology is used to generate layers inside and outside the contour.And finally,the Boolean algorithm between the layers is used to identify the suspension area to be supported.Secondly,research on segmentation algorithm of to be support area.Firstly,the stochastic Hough transform algorithm is used to fit the seed plane,set the threshold of the neighborhood,the normal vector angle and the distance,and add the matching point set to the seed region.Followed by regional growth,the same as the threshold for the regional growth conditions,it automatically adjusts the plane parameters.Experiments show that the segmentation algorithm realizes the accurate segmentation of internal and external regions.Thirdly,sparse tree support structure generation algorithm is proposed.For the segmentation of the external support area to be set,the existing support structure of the algorithm in the supplies and support stability is far from optimal.In this paper,the author mainly studies the algorithm of thinning of support points,supports of the cantilever length and strength constraints,and the optimization the support column.Experiments show that the algorithm produces sparse tree support structure of low consumption material,high stability,easy to remove and it has no damage to the ancient building surface.Fourthly,the thin-wall grid support structure generation algorithm is proposed.On the split out of the roof to be supported by the regional point set,the existing support generation algorithm is the use of honeycomb or entity to fill the internal.But it relatively wastes materials and time-consuming.This paper mainly studies the generation of single-sided thin-wall at equal intervals,and real-time filling support.Experiments show that the thin-walled grid support structure generated by the algorithm has high strength,low supplies and short printing time.Fifthly,implement and complete the system that automatically generates the support structure.Including the opening,operation and preservation of the three-dimensional model of the ancient building,the identification of the area to be supported,the segmentation of the supporting area,the formation of the supporting structure and other major functions.It promotes the physical display,archaeological restoration,and heritage of the ancient building.