Data from Digimap in AutoCAD
Accessing AutoCAD software
A wide range of Autodesk software, including AutoCAD and AutoCAD Map 3D, is free for educational use and can be downloaded from the Autodesk website.
Using Digimap Data in Autocad
Typical datasets that users want to work with include:
- OS MasterMap® Topography Layer
- MasterMap Topography Layer Building Height Attribute (BHA)
- OS VectorMap® Local (VML)
- OS Terrain™ 5 (Contours and DTM)
Comparison of using the above datasets in different versions of Autodesk software is given in the table below:
| Dataset Combinations | AutoCAD Map 3D | AutoCAD | Revit* |
|---|---|---|---|
| OS MasterMap® Topography Layer | Load DWG | Load DWG | Using the Construction Template… Use Insert –> Link CAD to add a DWG file. Toggle OFF “Correct lines that are slightly off axis”. Then select the Site Floor Plan view in the Project Browser To locate coordinates correctly go to Manage –> Coordinates –> Acquire coordinates and then click on the map (this will get the coordinates from the original file and move the Survey Point to 0,0). Check coordinates by using the Annotate –> Spot Coordinates to add coordinate to the map at a known point. If the coordinates are off by a factor of 1000 then you need to reset the units. (it seems to pick millimeters even though you choose metres at import time). Go to Manage –> Project Units and select Length and change Units to Metres |
| OS Terrain™ 5 DTM | Connect to the Surface …Data –> Connect to Data –> Add Raster Image or Surface Connection select the .ASC file then select Connnect and then Add to Map | Insert the XYZ data as a Point Cloud Use Insert –> Autodesk ReCap application to create a point cloud file. Select New Project –> Import scans and drag xyz file to screen or use “select files to import”. Then select Index Scans and then Launch project.You will see the DTM in 3D. Then save the project to an Autodesk ReCap Project file (.rcp). Close ReCap. In AutoCAD select Attach in the Point Cloud group and attached the .rcp file. Note you will need to manually specify the origin point. | After loading the Terrain 5 Contours… Select Massing & Site –> Toposurface Modify. Edit Surface –>Create from Import –> Select Import Instance and then click on the map. Accept the surface by clicking on the green tick. Select View –> 3D View to view the model in 3D.Or, using the Terrain 5 DTM XYZ data (note you will need to rename the .xyz file to a .csv file) Select Massing & Site then Toposurface then Create from Import –> Specifiy Points File and select the xyz file (note it will take a long time to load) |
| OS MasterMap Topo + Terrain 5 Contours | Load OS MasterMap Topo DWG then use Insert –> Attach (in the Reference Group). Select the Terrain 5 Contours DWG dataset and in the Attach External Reference dialog toggle on “Locate using Geographic Data “ and select OK. | Load OS MasterMap Topo DWG then use Insert –> Attach (in the Reference Group). Select the Terrain 5 Contours DWG dataset and in the Attach External Reference dialog toggle on “Locate using Geographic Data “ and select OK. | Open a blank project using the Construction Template. Load DWG OS MasterMap file into Revit using Insert –> Link CAD. Toggle OFF “Correct lines that are slightly off axis”. Go to the Manage tab and select Coordinates –> Acquire Coordinates and then click on the loaded map. Then load the Terrain 5 contours using Insert –> Link CAD and select “Auto - By Shared Coordinates “ in the “Positioning” mode. Select Open. |
| BHA + Terrain 5 Contours | Load BHA DWG then use Insert –> Attach (in the Reference Group). Select the Terrain 5 Contours DWG dataset and in the Attach External Reference dialog toggle on “Locate using Geographic Data “ and select OK. | Load BHA DWG then use Insert –> Attach (in the Reference Group). Select the Terrain 5 Contours DWG dataset and in the Attach External Reference dialog toggle on “Locate using Geographic Data “ and select OK. | Load BHA using I nsert –> Link CAD (note it might not work for very large files). Toggle OFF “Correct lines that are slightly off axis”. To locate coordinates correctly go to Manage –> Coordinates –> Acquire coordinates and then click on the map (this will get the coordinates from the original file and move the Survey Point to 0,0). To overlay contours select Link CAD and select the Terrain 5 contours. Toggle OFF “Correct lines that are slightly off axis”. Select “Positioning: Auto - By Shared Coordinates”. |
| VML + BHA | Load VML then use Insert –> Attach (in the Reference Group). Select the BHA DWG dataset and in the Attach External Reference dialog toggle on “Locate using Geographic Data “ and select OK. | Load VML then use Insert –> Attach (in the Reference Group). Select the BHA DWG dataset and in the Attach External Reference dialog toggle on “Locate using Geographic Data “ and select OK. | Load BHA using Insert –> Link CAD (note it might not work for very large files). Toggle OFF “Correct lines that are slightly off axis”. To locate coordinates correctly go to Manage –> Coordinates –> Acquire coordinates and then click on the map (this will get the coordinates from the original file and move the Survey Point to 0,0). Load VML into Revit using Link CAD and select VML dataset. Toggle OFF “Correct lines that are slightly off axis”. Select “Positioning: Auto - By Shared Coordinates”. |
| VectorMap Local | Load DWG | Load DWG. You may need to clip the data so that you only have a small area as it is delivered in 5km x 5km tiles (see below). | Load into Revit using Insert –> Attach Remember: To locate coordinates correctly go to Manage –> Coordinates –> Acquire coordinates and then click on the map (this will get the coordinates from the original file and move the Survey Point to 0,0). Check coordinates by using the Annotate –> Spot Coordinates to add coordinate to the map at a known point. If the coordinates are off by a factor of 1000 then you need to reset the units. (it seems to pick millimeters even though you choose metres at import time). Go to Manage –> Project Units and select Length and change Units to Metres |
*Note: Revit should only be used for datasets that are less than 20 mile (33km) radius because of the way it calculates precision and projects data.
Some common processes in different systems
1 Clip data
Often we deliver tiles in 5km square (e.g. VML) which is too big for many applications. The data needs to be reduced in size by clipping to a specific area. Guidance on clipping in different software:
In AutoCAD:
In AutoCAD 2016 you can delete features from a drawing by using the following commands at the command prompt after loading in the DWG dataset:
“Erase” “All” “Remove”
Then window the area you want to keep (by clicking on the map then dragging a box) and then press return.
This will delete all features outside your windowed area.
In AutoCAD Map 3D:
In AutoCAD Map 3D you can clip the area of data using the “Boundary Trim” command.
You just need to specify an area you want and select either inside or outside that area. You can then save the resultant cropped dataset. For full instructions on using it see:
In Revit:
There are various options in Revit for clipping and hiding regions of data:
2 Create 3D view in Revit
3D view
In Revit, BHA are the easiest way to create a 3D view.
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Open a New Project, units in Metric.
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Go to the Insert tab and select Import CAD and specify the DWG file.
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Go to View tab and select 3D View.
Create surface
To create a surface in Revit, you can use either Contours or DTM.
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Load in Terrain 5 Contours.
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Go to Massing and Site tab and select Toposurface.
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Select Create from Import –> Select Import Instance (for Contours).
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Click on the map the Add Points form Selected Layers interface will appear - see Image 1.
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Select all features.
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Select the Finish Surface tick.
You can also create a surface out of CSV data (X,Y,Z for each cell point).
Image 1 - Add points
Image 2 - 3D view.