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The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences. Vol. XXXVII. Part B5. Beijing 2008 
Ground industrial square modeling refers to automatic modeling 
of buildings, trees, roads, water, pools, cooling towers, 
chimneys, bunkers, and arbitrarily ground construction. 
Geologic modeling means automatic modeling of boreholes, 
geological units, protecting pillars, coal heaps, strata and so on. 
Underground engineering modeling refers to automatic 
modeling of various laneways, lane junctions, shaft stations and 
electromechanical equipments from mine design. External 
model input functions include input and output from 3DSMax, 
OBJ, WRL. 
2) VR information management functions. Those functions 
provide realistic and interactive virtual environment for users to 
walk or operate in the laneway models. 
Data input function can input various models and plug-ins from 
user-defined format or the third-party software. Specific effects 
editor include light rendering, sky texturing, particle system and 
voice warning, and the system support render and texture 
special effect. Database connection provides the database link 
and models attribute query. Scene compilation can render and 
compile scene independently and pack it into an executable 
program for release. Role management refers that different 
users have different password and different privilege. Virtual 
roaming is a function that users can walk or roam in virtual 
scene from ground to underground by keyboard and mouse, and 
fulfill the dynamic information management. 
3) Monitoring and controlling information system integration. 
Integrated with safety production monitoring and controlling 
system realize the all directional monitoring and controlling of 
the underground environment, facilities, disasters, and staff in 
3D environment, mainly including monitoring and controlling 
network, ventilation with gas-proof, dust-proof and fire-proof 
monitoring and controlling system, mine fire bundle tube 
monitoring system, industrial TV monitoring system and person 
position system. 
4. KEY TECHNOLOGIES 
In this section, 3 key technologies are introduced, including: 1) 
3D reconstruction of underground virtual scene; 2) collision 
detection; 3) industrial system integration. 
4.1 3D reconstruction of underground virtual scene 
A new algorithm of 3D laneway reconstruction from the 2D 
engineering plan for excavation was proposed. The engineering 
plan is the basic drawing for coal mining. According to this new 
algorithm, 3D underground laneway can be established as 
quadrilateral surface models or triangulated surface models 
according to surveying traverse points, section type of the 
laneway, laneway attribute and much else. And different color 
or texture can be set on the laneway model based on their 
attribute. The kernel of the algorithm is how to extract the 
useful information from 2D drawings and establish 3D laneway 
surface models automatically. 
4.1.1 Geometric feature of the laneway 
A laneway is composed of centerline, floor, roof, section and 
side face, shown as Figure 2. A complex laneway model can be 
divided into many single laneway models. Section type decides 
the shape of laneway model and the centerline determines its 
spatial position. Namely, the geometric feature is decided by 
the section type and the centerline. 
Generally, the section types are in various styles, such as U- 
type steel frame, three-sectional arch, round arch, one-centered 
arch, three-centered arch, lacking-circle arc, trapezoid arch.. 
Since the distance between the side face and the center line is 
fixed, the certain section can be loaded on the each nods of the 
center line and a regular laneway model is built. 
Figure 2. Configuration of a single laneway 
4.1.2 3D reconstruction of laneway model 
The principle of the algorithm is the control points of the 
laneway side surface are computed by loading the section on 
the node and mid-vertex of the centerline. After that, the control 
points are connected and the regularly triangulated surface is 
shaped. We take the round arch as an example to explain the 
modeling process. 
A round arch is composed of vertical wall h, width s and round 
roof r, shown as Figure 4. Granted that the coordinate of node O 
of the centerline, we can calculate coordinates of A, B, C, D 
according to s and h. If we break the round roof into pieces, we 
can calculate the coordinate of control points Bl, B2, B3, Cl, 
C2 and C3. 
During the whole modeling process, the key problem is how to 
calculate the surface points on a sharp bend, shown as Figure.3. 
Section A1A2 is loaded at node A, and section A1’A2’ is 
loaded at node P. In the same way, section B1B2 is loaded at 
node B, and section B1’B2’ is loaded at node P. A1’A2’ and 
B1’B2’ do not coincide with each other. Therefore, the surface 
model will be crossed partly and separated partly. 
Figure 3. Sketch map of sharp bend on the center line 
We give a simple method to solve this problem. As the section 
A,’A 2 \ A/’ is reduced to be Pj, A 2 is extended to P 2 . In the