1.3 Creating submodels: Buildings

This part will introduce the capability of modeling existing and proposed buildings that both are represented by 2D footprints. Alternatively, old/new construction can be included also in a true 3D form (like in *.ifc format). Therefore your site planning in terms of buildings can be achieved by using two alternative ways:

1. All major architectural/structural/MEP design packages can export your structure/building into *.ifc format (open data format) and use that as a reference for a current/proposed building/structure representation inside Explorer. We look those workflows in section: 02_Combined_VDC_model.
2. If you are having 2D footprints for your buildings that come from some geographic information system (GIS) system, you are projecting those 2D lines onto your surface and apply some rules that define the general look for your 3D building (LOD1). This workflow is mainly used for a quick context building and explained in the current tutorial. It is also possible to add a sloped roof surface (LOD2) and apply materials/textures for your buildings (surface/face based mapping).

General workflow

Step-by-step guidelines to include buildings onto a project site 

 

Open drawing Existing_Buildings.dwg inside AutoCAD Civil 3D. You should see a similar picture:

 

Using AutoCAD ribbon tab, go to Modeler and click on Rules. Modeler main toolbar opens:

 

 

 

Note: Modeler toolbar is the place where you create different rules that are applied to AutoCAD objects. All defined rules are kept in a separate file with an *.ini extension. Although it is possible to have only one *.ini file throughout your whole VDC project, where you define each and every rule that you want to use in separate drawing, in this tutorial we use the second method - we have separate *.ini file for each and every *.dwg file that we gonna use for generating data for VDC model. Using the latter method, please ensure that *.ini file is with the same name as your *.dwg file, then it will be selected automatically when you open up Modeler tools in your active *.dwg drawing session. Because with the current tutorial the proper *.ini file is already created, it will be automatically used. All rules are defined and we take a quick look to those rules that are important for each sub-task.

 

Next to each node, you will see a "+" icon if it holds some rules. And vice-versa, you can click on "-" icon, if you want to close that node. Also please note that in some nodes (ex Materials) you may have several rules. But those that are applied to current drawing are in bold. That feature is controlled through a menu: View > Gray Non-Existing Items.

 

 

We will first include the reference surface (terrain) into our VDC sub-model. This has been done through design package LandXML export. Please refer back to folder: 01_Existing\01_Terrain\Remain\LandXML, from where you also find two major LandXML files that represent the context and project area: 

 

You include both files under Modeler node LandXML. Because it has been already done for you, you can double click on each rule and see its parameters.

 

 

 

Double-click on a Terrain_ProjectArea (note: if you want to include your own reference, you just double-click the node LandXML itself and similar dialog as below, appears):

 

 

During a LandXML import you should fill in the following major parameters:

• Use Browse button to locate your LandXML file (in our example it is in: 01_Existing\01_Terrain\Remain\LandXML).
• Enter the group (subgroup) name to where this information is attached (this is important to keep your project organized).
• Select what data you want to include into your model, selecting rows (if multiple present) under Groups section.
• For a reference purpose, the material is not important, also the Cut Mode is not important (refer to general help topics if you plan to use those in your own projects).

Click OK to accept the values and close the dialog.

 

Double-click on another predefined rule, Terrain_Context.

 

 

This represents the context around project area. Check the settings and click OK to close the dialog.

 

Because we use those LandXML files as reference surfaces for our building's footprints, we need to generate layers by which our building rules know about the elevation of our project area (Modeler is using layer-based or object-based rule mapping).

 

For an automatic generation of that layer, click on Generate Model button:

 

 

Although it generate a *.vm file to the same location as your *.dwg file, it is not yet ready to use inside our final VDC model. Because it is not correctly defined. During this generation, two new layers were added (because we use two LandXML rules). The new layer is always generated as long as you change the group or content (in our case, surface) name. Therefore it is good if you always clean-up those layers, that you do not need. Because this layer is not a real layer (no AutoCAD objects are on that), please be careful when you use AutoCAD Purge command. This will remove those layers as well. Still, Purge command is the easiest way to clean up your drawing.

 

Let's take a look into Buildings section. As you see there are several rules (each row is a different rule). If it is in bold, it is used in the current project (meaning that Modeler understands, that with that particular layer there are some objects in your *.dwg). Rules in general can be taken so, that you have different rule for different object type you want to get/see. Therefore if some parameter value inside one rule is different from another rule, you have made two different rules.

 

Open up (double-click) a first bold rule under Buildings node.

 

Let's go through some major settings that help to define your building:

• layer - all 2D closed polylines should be mapped onto that layer if you want to convert it into 3D building (layer name can be anything you want, just ensure that you have selected correct layer).
• materials - select one or multiple materials that you want to apply for your building shape (in large areas, it is recommended to select multiple materials, because in that way you can easily define some randomness into your context).
• description - this can be used to shorten the name that is visible in Modeler main toolpalette. Not a required parameter. In this example the same name is used, as for layer parameter.
• info text - additional description, text that you may want to include that is available in the model.
• rooflinelayer - because your building's roof may not follow the building's footprint exactly, you can define on what layers those roofline 2D polylines can be found.

Please refer to general help topic, to figure out the building's main geometry parameters like: baseheight, eavesWidth, floorheight, nrfloors, roofheight. Note that all those values are entered in drawing units.

• roofmaterial - you can select different material for your roof component (again, you can add randomness by selecting various materials).
• basematerial - you can select different material for your base component.
• interpolate_to_layers - this is where you select those layers that will be used to raise your buildings to. You can select multiple layers here, but please be aware that if those references do overlap (or your footprint can follow both references at its X,Y location, you also get multiple objects to your final VDC model - typically you do not want that to happen).
• group - select a group to where your buildings are assigned.

Note: Groups are automatically generated/added when you write those into group field in Change Setting dialog (remember to add a "/" for a subgroup). Alternatively you can create groups through a menu: Model > Groups...

 

 

It will open up a separate dialog where you can see a group selection tree. Although some prefer to include all group levels into each and every *.ini file, please be aware that even if you have not mapped any object onto that subgroup, it will be still included into your *.vm file. Of course it is an empty node there, but sometimes it makes it difficult to find objects that you need, if you have loads of empty group nodes.

 

Click OK to close the dialog Change Setting. You are now ready with one of your building rule. But because there are different building shapes, we create each rule for each different building shape. Altogether you can see that we have 8 rules. Take a look to each of those and see the differences. Once done, click on a button: Generate and View Model.

 

 

This will regenerate your model (as you did before) and also opens up a Explorer as a viewer package for your *.vm file. Please also note that your *.vm file is automatically placed to the location where your *.dwg resides. Your sub-model should look similar to the following image:

 

 

If you take a closer look to your model, you can see that it includes the terrain (surface) from LandXML files. Those are included in another group and therefore we want to get a clean Existing Buildings sub-model for our final VDC model.

 

To remove those references, just follow those easy steps:

 

Go to tab Output and select Export to File:

 

New dialog will open, from where you use:

• Groups - select groups that you want to export into new *.vm file (you can select multiple groups). In the current case it will be only: Existing/Buildings/Remain
• Export Format - select: VM File
• File Name - point to a location where your original *.vm file is, but do not overwrite it, use a special ending like: *_Only.vm

 

Click Save to export your model into a new file. You can now reopen that file, and see if you have only building data.

 

Note: In your group selection tree you still see those LandXML reference nodes, but those are now empty. That is why it is important to keep everything with the same group logic.

 

After checking your existing buildings sub-model, you can close the Explorer window. Later you can open those *.vm files directly with Explorer and you do not need to follow Modeler workflow again. Of course, when the design changes, then you recreate the *.vm file.

 

As you have successfully generated a existing buildings sub-model, it is also good to save your Modeler *.ini file. For that, just select from the menu: File > Save Configuration...

 

You can re-select the location and name for your *.ini file, but in this tutorial it is recommend that you always keep the same name for your *.ini file as you have named your *.dwg. And also ensure, that both files (*.ini and *.dwg) are saved to the same location. 

You can close the Modeler dialog. It will warn you, if you want to save your settings. Because you just did it, you can simply dismiss that warning. Click No (or Yes, if you think that you need to re-save your settings).

 

 

Close the AutoCAD drawing file.

 

Practice yourself

Because the proposed building *.dwg file (\02_Design\02_Buildings\VM\Proposed_Buildings.dwg) share the same procedures as currently shown, you can practice that one on your own. If you open that *.dwg file, and after that also Modeler dialog, you will see that new settings file (*.ini file) will be loaded that holds all needed rules for that specific *.dwg. The major difference in this file is, that it uses a different LandXML reference (\02_Design\01_Terrain\LandXML\Parking_lot_asf.xml). That LandXML represents a new parking lot area, and has been generated from a design package through a LandXML export.

 

Repeat the process and in the end you should have 2 different *.vm files from this section that you will use in final VDC model (with the ending of *_Only.vm).

 

Note: When you work with Modeler and save your *.ini files, system automatically creates backup versions of the previous file. Sometimes it is good to think that you have some previous definition files still available. In this tutorial we have not kept those *.bak files as well as no separate backup folders. If something goes wrong, you can extract (copy) needed definition (and *.dwg) files into your current working folder and start again. Therefore in a clean system (with no backups, no *.dwg backups as well) you folder may look like this:

 

Folder: 01_Existing\02_Buildings\Remain\VM

Folder: 02_Design\02_Buildings\VM