Using the 3d in AutoCAD Map 3d

3 February , 2008

Hi all – today’s post is all about the 3d!

Well if you are anything like me you have called the software ‘Map 3d’ many times but have all to often ignored the 3d part! When speaking to customers I often hear “We only work in 2d” or “3d would be nice but it takes to long to get results” – Well in this post I want to show you thats not always true!

AutoCAD Map 3d has a great, fast, easy way to produce a 3d visualisation. Although the product has no capabilities for creating surfaces from X,Y,Z data – you will require AutoCAD Civil 3d for that – you are able to connect to existing 3d surfaces that have been created externally to AutoCAD Map. These include DEM (Digital Elevation Model) files, ESRI Grid files (asc Grid), or Digital Terrain Elevation Data (DTED).

Here in the UK for example there are a number of sources I can purchase pre-existing 3d surface data that will read directly into AutoCAD Map. One such source is from a comapny called eMapSite that offer a range of digital geospatial data, including 3d surfaces – The data in this example was kindly provided by them.

To access the data within AutoCAD Map you use the Feature Data Objects (FDO) technology, which connects directly to the file and displays it within the DWG. Once you have connected to the raster-based surface, you can create contour maps to help you analyze 3D terrain. You can use raster-based theming to analyze elevation, slope, and aspect, and drape other map data over the surface. You can also view the data in 3D with walk-through and fly-through options, creating compelling visualisations.

Here are 5 quick steps to produce a 3d visualisation and perform some flooding analysis.

Step 1 – Connecting to the 3d surface file

Open the ‘Data Connect’ menu from the ‘Display Manager’ and select the ‘Add Raster Image or Surface Connection’. Navigate and select the surface file you wish to add (in my case its a .asc). Then tick the box and hit ‘Add to Map’. This will add your 3d surface connection to your DWG in the same way you would add any other raster file.

Your surface will now appear in Model space and the layer will appear on the Display Manager.

Step 2 – Adding additional data to drape onto the surface

To add an aerial photo to drape onto the surface, open the Data Connect menu again and select the ‘Add Raster Image or Surface Connection’. But this time add an aerial photograph or other relevant raster file that you have. 

When you view this data in 3d the raster image will drape automatically onto the 3d surface. It is also possible to use the FDO access tools to connect to vector data which will then automatically drape on the surface also.

Tip – When dealing with DWG CAD entities, these will NOT drape on the surface so you need to ensure the entities are given the correct elevation to appear in the correct place in the 3d world.

Step 3 – Adding the flood surface

To enable me to produce some flood analysis I need to create an object to represent the flood. To do this you can add a simple polygon CAD entity.

Draw a polygon around the surface – You may wish to snap your polygon to the edge of the surface to make the visualisation clearer. Once completed select the properties of the polygon and change the colour fill setting to Blue.

Step 4 – Visualising the data in 3d

Now its time to view the data in 3d.

Select the ‘3d Mode’ button underneath the Model space tab.

Tip – It’s important you use this button to switch to 3d mode as it applies the stylisation settings required.

The data is now viewable in 3d and you can use the 3d navigation tools to move around.

Step 5 – Adding the Flood height

Finally you can specify the height of the flood you want to analyse. 

Select the blue polygon underneath the 3d model, right mouse click and select ‘Properties’. In the properties editor, underneath the ‘Misc’ section, enter your flood height into the ‘Elevation’ field.

Before Elevation Change

After Elevation Change

This will raise the polygon on the Z axis to the relevant height and cut through the model.

Hopefully you will all agree that once you have the right 3d surface data, this is quick, easy and a great starting point for creating compelling visualisations and fly-throughs.

There are a number of other things you can do with the surface, including style it based on Height, Slope and Aspect; plus you can produce a contours dataset from the surface. I have written a short ‘How 2’ guide on how to insert and style 3d surfaces in AutoCAD Map 3d, which . If you are interested please drop me an email –

See you next time.