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Are You Taking Full Advantage of Civil 3D?

Tip #1 – Learn What You Need to Learn

When you first learned AutoCAD® Civil 3D®, did you take official training? What did that training include? Did you just learn how to create AutoCAD Civil 3D objects such as surfaces from survey points, parcels, alignments, profiles, and corridors? Many seasoned users of AutoCAD Civil 3D realize that they can use generic AutoCAD commands to complete tasks more efficiently in AutoCAD Civil 3D. However, I am constantly surprised by how few people know that they have access to AutoCAD® Map 3D® commands as well. You see, Civil 3D was built on top of Map 3D which was built on top of AutoCAD. This means that you have a lot more tools available than you may realize.

The Planning and Analysis Workspace (shown in Figure 1) in the AutoCAD Civil 3D software provides access to tools found in the AutoCAD Map 3D software. They help you attach and analyze geographic information systems (GIS) data for more efficient planning of projects before starting a design. Taking advantage of these tools allows you to bring in elevation data before a survey crew even steps foot on the project site. You can also bring in parcel data, existing road centerlines, and many more readily available GIS datasets from government and other agencies.

Figure 1; Planning and Analysis workspace

Trick # 1 – Finding GIS Datasets

GIS data is available from many different sources. Agencies around the world recognize the benefits of sharing information such as parcel linework, soil data, land use information, wetland data, and much more. Depending on where your project is located, you can find a lot of data online. Here in Utah, we have the Automated Geographic Reference Center (http://gis.utah.gov/) along with many other county and city government agencies that provide GIS data. To find data for your project, do a search on the Internet. Wikipedia (http://en.wikipedia.org/wiki/List_of_GIS_data_sources) has links to many sources worldwide.

Tip #2 – Download All Associated Files

Once you find data, it is extremely important to download the right information. I recommend downloading all the associated files to ensure you have everything you need. Figure 2 shows all the files associated with a floodplain dataset for Utah. If you find a shape file for your project, you must download the .dbf file to see the data behind the linework. It is also important to download the projection file (*.prj) so that the AutoCAD Civil 3D software knows how to automatically re-project the dataset into the project’s coordinate system.

Figure 2: GIS dataset for floodplains in Utah

Trick #2 – Set the Geographic Location

Coordinate systems are used in engineering and mapping to uniquely identify the position of geographical elements. Each coordinate system uses different mathematical formulas to accommodate the curvature of the earth’s surface.

GIS data comes in many different coordinate systems. Many people lack the cartographic and/or math skills to re-project one coordinate system into another coordinate system accurately. Fortunately, Autodesk has made this much easier for users by pre-programming the software to do re-projections automatically. The trick to making this work is to communicate with the software.

The software needs to know two things:

1. The coordinate system the project is in
2. The coordinate system the referenced data is in

The second one is easy as long as you follow Tip #2 and download all the associated files with the dataset. That is because the projection file (*.prj files for shape files) communicates the dataset’s coordinate system for you. If a projection files is not included with the dataset, then the metadata file will communicate that information to you. Then you just have to communicate it to the software.

To communicate to the Autodesk software the coordinate system your project is in, either use the AutoCAD Civil 3D Toolspace or the AutoCAD Map 3D Assign command.

Set the Coordinate System Using the AutoCAD Civil 3D Toolspace

1. On the Setting tab of the Civil 3D Toolspace, right-click on the drawing name and select Edit Drawing Settings.
2. On the Units and Zone tab of the Drawing Settings dialog box, select the appropriate category and coordinate system, as shown in Figure 3.
3. Click OK.

Figure 3: Drawing settings

Set the Coordinate System Using the AutoCAD Map 3D Assign command

1. In the Workspace Switching Tool, select the Planning and Analysis workspace.
2. In the Map Setup tab, Coordinate Systems panel, click Assign.
3. In the Coordinate System - Assign dialog box, select the appropriate Category and coordinate system, as shown in Figure 4.
4. Click Assign.

Figure 4: Coordinate System - Assign dialog box

Tip #3 – Take Advantage of Existing Data

Once you have set up the coordinate system for your project, then you can take advantage of existing GIS data that you have downloaded from other agencies. Bringing in GIS data can be done in a couple different ways. If bringing in point, line, polygon, or image data, it is best to connect to the data using Map 3D tools. This helps keep the size of the drawing file down since it acts like a reference. It also makes it much easier to display the data the way you would like. If bringing in ground data such as a DEM files or ESRI ASCII Grid (*.asc) files, then using Civil 3D surface creation tools may suit your needs better.

Trick #3 – Connect to GIS Data

The process used to connect to GIS data is similar regardless of the type of data being connected. You can connect datasets from many different providers, as shown in Figure 5. You also have the option to connect one file at a time or an entire directory of files at the same time. If a database connection is required, you will be asked to input login credentials.

Figure 5; Data Connect palette

Open the Data Connect Palette

1. In the Civil 3D Workspace, Home tab, expand the Palettes panel and click Map Task Pane, as shown in Figure 6.
2. In the Display Manager tab of the Map Task Pane, click Connect Data.

Figure 6: Open Data Connect palette

Trick #4 – Create Civil 3D Surfaces from GIS Data

Although you can connect to ground elevation data through the Data Connect palette, you may find that you need to create a Civil 3D surface rather than just viewing the raster file. Figure 7 shows the same digital elevation model (DEM) as a connected raster file and as a Civil 3D surface.

Creating a Civil 3D surface from GIS data has many benefits. The most important benefit is that you can do project planning using tools that you use during the detailed design. You can also take advantage of any design data you create in the preliminary design once the project moves into the detailed design phase. If you create alignments in the preliminary design phase, existing ground profiles can be quickly created from the GIS Data surface. If you create corridor models in the preliminary design phase, they can be reused in the detailed design phase by simply changing out the surface it is referencing to the newly surveyed surface.

Figure 7: Connected raster file versus a Civil 3D surface

Create a Civil 3D Surface from GIS Data

1. In the Civil 3D Workspace, Home tab, Create Ground Data panel, expand Surfaces and select either Create Surface from DEM or Create Surface from GIS data, as shown in Figure 8.
2. If you selected Create Surface from DEM, then select the DEM file and click Open to end the command.

Or

     3.  If you selected Create Surface from GIS Data, then a wizard appears. Follow the steps in the wizard, clicking Next at the end of each page.

     4.  When done, click Finish.

Figure 8: Expanded surfaces menu

Note:

The option used for creating a surface from GIS Data depends greatly on the type of files provided for the site. If a USGS DEM (*.dem), Geotiff (*.tif), or ESRI grid file (*.asc, *.txt, *.adf) is supplied, then you must use the Create Surface from DEM command. If you have an ArcSDE, Oracle, of Shape file, then you must use the Create Surface from GIS Data command.

This article is not nearly long enough to introduce all the wonderful Map 3D commands available inside Civil 3D. In fact, there is so much available that I could write an entire book on it. (Oh wait, I already did.) So I highly recommend that you go back to Tip #1 and learn more about what else you need to learn. I guarantee that you will be more productive if you do. Until next time, good luck and happy project planning!

Michelle Rasmussen started in the Air Force working in the Civil Engineering unit as a surveyor, designer, and construction manager in the early 1990s. She has worked for both municipalities and consulting engineering firms as an engineering/GIS technician where she completed transportation studies, environmental impact studies, and drafted subdivision and site plans. Michelle has been training people on Autodesk products since 2000 and is currently an author for ASCENT (ascented.com) where she writes books for Autodesk infrastructure software products such as AutoCAD Civil 3D, Autodesk InfraWorks, and AutoCAD Map 3D.