## 3 Model-GIS Coupling Strategy
### Implementation of the LBM Integrated with LrGIS Platform  
Numerical model and GIS integration can be achieved using one of the three potential coupling strategies outlined in Table 1[28]. Here, a tight coupling approach is used to integrate LBM in LrGIS platform, which requires a straightforward connection from the geometric laneway data to LBM based numerical model. An applicable numerical coupling model was developed, which was specifically designed to adapt geometric laneway data to be integrated with LrGIS platform. The implementation procedure focuses on improving the geometry of the input features that configure the model geometry, the boundary conditions, and other aspects of spatiotemporal modeling, which avoids explicit mesh generation procedure that is necessary in traditional CFD method. It will help modelers in the development of future projects. Figure 3 shows the entire architecture of numerical model integrated with LrGIS platform. The platform consists of three layers: Data source, GIS kernel, and desktop application. Different kinds of data source can be quickly stored, retrieved, indexed, and searched by SDE interface layer. GeoLattice can be constructed on LrGIS platform to prepare for the numerical simulation, like other geometric models such as GeoPoint, GeoLine. In terms of the data management, LrGIS contains many entity models, such as GeoEntity, RasterEntity. Similarly, FluentEntity is specifically designed to manage the field data obtained by fluid simulation. The physical attributes consist of velocity, pressure, temperature, gas concentration, and display attributes comprise geometrical shape, color rendering, profile. The simulated result can be visualized on LrGIS GUI and execute the spatial query function. Specifically, two main parts have been solved: (i) GeoLattice and FluentEntity setup, which constructs the laneway model and configures the geometry and attributes of each lattice to make them valid for numerical computation; (ii) Database organization, which controls and traces the output data that are obtained from the numerical simulation. The data is saved as time series grid table files, which can be called by FluentEntity. \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Characteristics**} & \multicolumn{3}{c}{**Coupling Type**} \\ \cline{2-4}  & **Loose** & **Tight** & **Embedded** \\ \hline Shared data and method base & & \(\surd\) & \(\surd\) \\ \hline Intra-simulation model modification & & & \(\surd\) \\ \hline Intra-simulation query and control & & & \(\surd\) \\ \hline \multirow{6}{*}{Advantages \& disadvantages} & Different GIS and Modeling packages have independent interfaces. Information sharing is based on exchange of files, which can be error prone and inefficient. Different tools and libraries facilitate independent development development. & The coupled platform merges different modules in a single powerful system, which avoids inconsistency and data loss originating from redundancy & Programming and data management is significantly complex, and the code base is not easy to be changed due to knowledge may be embedded large source code structure. \\  & & & \(\surd\) \\ \hline Examples & [48] & [49] & [50] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Characteristics of different strategies for GIS and model integration. Figure 3: The entire architecture of numerical model on LrGIS platform. The lattice attributes and the corresponding boundary conditions are described in details: different kinds of lattice nodes on the geometry are associated with different material numbers in their own coordinates. Figure 4 presents a 2D top view of the lineway, with material number one, two, three, four and five corresponding to fluid region, inflow, outflow, methane mass flow, and bounce back boundary, respectively.