• “Reviewing Your Results” on page 5-146
Preparing to Use ModelBuilder
• Determine the purpose of your model—Once you establish the purpose of your model, you can start to make decisions about how detailed the model should be.
• Get familiar with your data—ModelBuilder supports several data source types, including tabular and geometric. Tabular data sources include spreadsheets, data- bases, and other data sources without geometric information. Some supported tabular data source types include Microsoft Excel and Microsoft Access. Geometric data sources, while also internally organized by tables, include geometric characteristics such as shape type, size, and location. Some supported geometric data source types include the major CAD and GIS file types
If you obtained your model data from an outside source, you should take the time to get acquainted with it in its native platform. For example, review spatial and attribute data directly in your GIS environment. Do the nodes have coordinate information, and do the pipes have start and stop nodes specified? If not, the best method of specifying network connectivity must be determined.
Contact those involved in the development of the GIS to learn more about the GIS tables and associated attributes. Find out the purpose of any fields that may be of interest, ensure that data is of an acceptable accuracy, and determine units associ- ated with fields containing numeric data.
Ideally, there will be one source data table for each SewerCAD V8i element type. This isn’t always the case, and there are two other possible scenarios:
Many tables for one element type—In this case, there may be several tables in the datasource corresponding to a single GEMS modeling element, component, or collection. In this case each data source table must be individually mapped to the SewerCAD V8i table type, or the tables must be combined into a single table from within its native platform before running ModelBuilder.
One table containing many element types—In this case, there may be entries that correspond to several SewerCAD V8i table types in one datasource table. You should separate these into individual tables before running ModelBuilder.
• Preparing your data—When using ModelBuilder to get data from your data source into your model, you will be associating rows in your data source to elements in SewerCAD V8i. Your data source needs to contain a Key/Label field that can be used to uniquely identify every element in your model. The data source tables should have identifying column labels, or ModelBuilder will inter- pret the first row of data in the table as the column labels. Be sure data is in a format suited for use in ModelBuilder. Note that while ModelBuilder allows duplicate labels, they may cause ModelBuilder to give unexpected results when two elements of the same type have the same label. Where applicable, use powerful GIS and Database tools to perform Database Joins, Spatial Joins, and Update Joins to get data into the appropriate table, and in the desired format.
Note: When working with ID fields, the expected model input is the SewerCAD V8i ID. After creating these items in your SewerCAD V8i model, you can obtain the assigned ID values directly from your SewerCAD V8i modeling file. Before synchronizing your model, get these SewerCAD V8i IDs into your data source table (e.g., by performing a database join).
• Preparing your CAD Data—In previous versions of SewerCAD V8i, the Poly- line-to-Pipe feature was was used to import CAD data into a SewerCAD V8i model. In v8, CAD data is imported using ModelBuilder. When using Model- Builder to import data from your CAD file into your model, you will be associ- ating cells in your CAD drawing with elements in SewerCAD V8i.
Different CAD cells will be recognized as different element types and presented as tables existing in your CAD data source. It is recommended that you natively export your AutoCAD .dwg or Microstation .dgn files first as a .dxf file, then select this .dxf as the data source in ModelBuilder. Your data source will most likely not contain a Key/Label field that can be used to uniquely identify every element in your model, so ModelBuilder will automatically generate one for you using the default "<label>". This "<label>" field is a combination of an element's cell type label, its shape type, and a numeric ID that represents the order in which it was created.
• Build first, Synchronize later—ModelBuilder allows you to construct a new model or synchronize to an existing model. This gives you the ability to develop your model in multiple passes. On the first pass, use a simple connection to build your model. Then, on a subsequent pass, use a connection to load additional data into your model, such as supporting pattern or collection data.
Note: Upon completion of your ModelBuilder run, it is suggested you use the Network Navigator to identify any connectivity or topological problems in your new model. For instance, Pipe Split Candidates can be identified and then automatically modified with the Batch Split Pipe Tool (see “Batch Pipe Split Dialog Box” on
page 4-262). See “Using the Network Navigator” on page 4-278 for
more information.
• Going Beyond ModelBuilder—Keep in mind that there are additional ways to get data into your model. ModelBuilder can import loads if you have already assigned a load to each node. If, however, this information is not available from the GIS data, or if your loading data is in a format unrecognized by ModelBuilder (meter data, etc.), use LoadBuilder; this module is a specialized tool for getting this data into your model. In addition, with its open database format, SewerCAD V8i gives you unprecedented access to your modeling data.
One area of difficulty in building a model from external data sources is the fact that unless the source was created solely to support modeling, it most likely contains much more detailed information than is needed for modeling. This is especially true with regard to the number of piping elements. It is not uncommon for the data sources to include every service line. Such information is not needed for most modeling applica- tions and should be removed to improve model run time, reduce file size, and save costs.