Applied Mechanics and Materials
ISSN: 1662-7482, Vols. 229-231, pp 1807-1810
doi:10.4028/www.scientific.net/AMM.229-231.1807
© 2012 Trans Tech Publications, Switzerland
Online: 2012-11-29
Automatically Generate Three-dimensional Pipelines Based On
GeoDataBase MultiPatch Model
GuoHuang Li, HuaJun He
Department of Mathematics and Physics, North China Electric Power University
Department of Mathematics and Physics, North China Electric Power University
[email protected]
Keywords: MtultiPach, Three-dimensional Visualization
Abstract. With the development of city, the scale of underground pipeline is always extending and
to solve the problem of virtual underground pipeline generation is extremely urgent. In this paper,
we will use the triangular slice to establish three-dimensional MultiPatch models. The
three-dimensional vector will be used in this new modeling method of 3D visualization of
underground pipeline. The method can automatically deal with elbows or straight pipe modeling
problems. And we find it suitable for rapid modeling and wide range of applications through our
series of test.
Introduction
The underground pipeline mainly refers to the urban underground pipeline, which belonging to
public facility. The urban underground pipeline can be divided into the following seven categories:
water supply, drainage, gas, heat, industrial, Electric power, and telecommunications lines [1].
Underground pipeline distribution cannot be fully expressed by plat sheet due to its complexity,
especially in urban underground pipelines system with a variety of pipeline along the street lying in
the ground at different depths. Two-dimensional graphics cannot show the spatial position between
the pipelines. However, with the development of GIS technology and computer technology, to
generate 3D pipelines becomes possible.
Brief Point on ArGIS 3D Model and GeoDataBase
MultiPatch is a data type of three-dimensional feature provided by ArGIS and it’s used to
represent a surface model of the geometric boundaries of the three-dimensional objects. MultiPatch
can mainly group into four categories: the Triangle Fans, Triangle Strips, Triangles and Rings, the
triangular strip refers to a series of interconnected triangles composed of three-dimensional
geometry shape.
GeoDataBase is a set of object-oriented spatial data model to support the topological relations
between feature elements, expanding complex network-based elements and other types of
object-oriented data and relational functions. Modeling the real world through the GeoDataBase in
GIS accurately reflects the properties and behavior of objects in the real world. GeoDataBase
object's role is to provide users with an advanced GIS information model, which can be seen as an
accurate simulation of the real world. And GeoDataBase provide a way to integration seamless
storage, unified management, and intelligence.
All rights reserved. No part of contents of this paper may be reproduced or transmitted in any form or by any means without the written permission of Trans
Tech Publications, www.ttp.net. (ID: 130.203.136.75, Pennsylvania State University, University Park, USA-17/05/16,18:23:27)
1808
Mechanical and Electrical Technology IV
Process of Establishing Pipeline Model
Concerning model of three-dimensional pipeline, HeHua Zhu [2] propose to create a
three-dimensional geometric model based on the slice, and use the triangular faces of the delaunay
algorithm to construct beginning and ending section of the class of cylindrical surfaces.
Furthermore, each pipeline can be seen without considering the wall thickness of the thin-walled
pipe and connecting the pipe bending parts. Space geometric properties of the pipeline consist of the
starting point, terminated point in pipe, diameter, the starting point for depth, the terminated point
for depth, and other fields.
Model of straight pipe
In terms of straight pipeline we can use the data of starting point in pipe and terminated points
to construct three-dimensional vector furthermore calculating the point on a direct pipeline on the
bottom round and top round, and then use these points to construct direct pipeline MultiPatch,
concrete steps are as follows:
Known straight pipeline’s information including starting point
P1(X1, Y1, Z1), terminated point P2(X2, Y1, Z1) and the diameter R value.
1) Initialize two three-dimensional vectors:
P1P2=upperVector3D
P2P1=lowerVector3D
2) X, Y, and Z values of lowerVector3D increase an offset; we can get a three-dimensional
vector named pVector3D;
3) Making multiplication cross between pVector3D and upperVector3D, resulting in a new
normal vector named normalVector3D occupying in the same plane formed by two formers.
4) Adjusting mode long of the vector normalVector3D into the same value of diameter R. (it is
shown in figure 1.)
5) Rotating the normalVector3D around upperVector3D by certain angle (if the circle is
divided into 20 equal parts, each rotation of 360 ° / 20 = 18 °). Respectively, P1 and P2 are the
centers of two circles which center will plus normalVector3D’s X,Y and Z values to get the edge
points on the circle of the cylinder up and down. And finally we get a collection of points to form a
points list.
6) Points in list will be added to a TriangleStrip to form a straight pipeline MultiPatch.
upperVector3D
normalVector3D
pVector3D
lowerVector3D
Fig.1 Graph of 3D vector
Model of elbow
In three - dimensional view, we can use the cylinder to draw direct pipeline and describe elbow line
section by a ring with certain angle. We can take a strategy that ring is divided into many shorter
straight cylinder. And when the cylinder is divided enough, the final effect can reach the sleek
requirement of elbow.
Assuming Known first pipeline, containing starting point named FromPoint1, terminated point
named ToPoint1 and second pipeline, containing starting point named FromPoint2 and terminated
point named ToPoint2. Elbows can be created by following steps:
1 When the radius of first pipeline and second pipeline are both equal to value R.
○
Applied Mechanics and Materials Vols. 229-231
1809
1) To connect ToPoint1 and FromPoint2 and then we get a straight line with the certain length
of value Length. And we divided it into N equal portions;
2) Draw arc under the conditions that put ToPoint1 as the center of the circle and the value of
radius is K*Length/N (1≤K≤N).
3) Construct a three-dimensional vector named pVector1 from FromPoint1 to ToPoint1. And
then we build another three-dimensional vector named pVector2 from FromPoint2 to ToPoint2.
Constitute vector named pMidVector with ToPoint1 and FromPoint2; calculate the angle between
pVector1 and pMidVector.
4) Rotate pVector1 by angle of value Angle/N, and the length of value K*Length/N (1≤K≤N)
will be assigned to pVector1’s mold long when the frequency reaches k round; Through each
rotation we can get a 3D point (ToPoint1.X + pVector1.X, ToPoint1.Y + pVector1.Y, ToPoint1.Y +
pVector1.Y) and in turn connect the dots, an almost smooth curve containing path from ToPoint1 to
FromPoint2 can be obtained when N reaches a certain value. The process is shown in figure 2.
Fig.2 Prime Points In the curve of elbow
5) To connect two adjacent points in arc, and get upperVector3D, lowerVector3D and
normalVector3D in method of constructing straight pipeline. Diameter R will be assigned to model
long named Magnitude of normalVector3D. Then we rotate vector normalVector3D to obtain the
points belonging to ring surfaces, and join those points to MultiPatch TriangleStrip in order to get
the elbow. The effect is shown in figure 3.
2 When the radius of pipeline1 and pipeline2 are totally different, assuming the radius value of
○
pipeline1 is R1, however, another one is R2. Just keep the linear change on radius of the elbow from
value R1 to value R1+m*(R2-R1)/(N-1). The values of m cover the range from 0 to N-1). So we can
deal with the smooth problem in that way. The effect is shown in figure 4.
Fig.3 Two elbows with the same diameter in
different depths.
Fig.4 Two elbows with different diameters in the
same depth
1810
Mechanical and Electrical Technology IV
Automatically Generate Three-Dimensional Pipeline
After established a model of straight pipes and elbows, we automatically generate 3D pipeline.
Firstly the system creates a 3D pipeline table in the database named GeoDataBase,. And then
system read two-dimensional data of pipeline in GeoDataBase. Using ArcGIS Engine 3D module to
construct straight pipe and elbows’ MultiPatch and stored in the OLE object in the database table,
and finally load the 3D pipeline data, read the OLE object and render, display, and our system can
automatically generate three-dimensional pipeline. The results are shown in figure 5 and figure 6.
Fig.5 Automatically generate 3D pipeline
Fig.6 The portion of a pipeline
Conclusion
Visualization of the 3D pipeline objective reflect the relationship of the underground pipe
network and provide reliable information to help the construction of the building for the city
planning and management of the city's pipeline. This article provides a model in form of
MultiPatch, the method that using GeoDataBase to stored MultiPatch model help speed up the
rendering speed of the 3D model.
References
[1] Yingzhong Tian, Zhangzheng lu, xu yang, “Detection of underground pipeline network and
information management in Beijing”, Surveying And Mapping Press, 1997.
[2] HeHua Zhu, JiangBing Wu, “visual 3D Pipeline modeling”, Chinese journal of Underground
Space and Engineering,2005.
Mechanical and Electrical Technology IV
10.4028/www.scientific.net/AMM.229-231
Automatically Generate Three-Dimensional Pipelines Based on GeoDataBase MultiPatch Model
10.4028/www.scientific.net/AMM.229-231.1807