Tutorial – AutoCAD Civil 3D Surface to Revit Topography

Over the next few months I will be posting some tutorials and workflows for taking civil engineering models such as drainage layouts and retaining walls from AutoCAD Civil 3D to Revit. The reasons for these workflows are to increase the Level of Detail and information that is held within the models. For example, the coordination and documentation of foundations with new drainage and existing underground services can be achieved very efficiently with the use of AutoCAD Civil 3D and Revit. This is even more relevant with the introduction of Autodesk Collections which will have Revit and AutoCAD Civil 3D available to all! See this link for a full list of products that are available in the Autodesk AEC Collection

https://www.autodesk.co.uk/collections/architecture-engineering-construction/included-software

In this first post I will concentrate on the fundamental task of getting a TIN (Triangular Irregular Networks) surface from AutoCAD Civil 3D to Revit as a 3D TOPO.

Triangulation

AutoCAD Civil 3D and Revit each use slightly different algorithms for the triangulation of surfaces. This could potentially allow errors to creep in if we simply rely on points and use these points to build surfaces in Revit and Civil 3D. In practice you should create the Revit Surface directly from the AutoCAD Civil 3D triangles. In the example below you can see a triangulation model from AutoCAD Civil 3D with the points shown in red and the levels shown in blue.

TIN Surface Original Trangles

In the image below the Revit Triangulation algorithm is shown in red. The points are connected in a different order and can cause minor differences in levels.

TIN Surface Revit Traingulation

To ensure that AutoCAD Civil 3D is showing triangles, select the Surface and then select ‘Edit Surface Style’ from the Right Click context menu. Select the Display tab, make sure that the View Direction is set to Model and ensure that Triangles are visible and all other component types are switched off.

Civil 3D Surface Style Triangles

Datums

To ensure correct coordination to Revit you should clearly mark a survey station that you would like to reference and also a project base point. An example may look similar to the image shown below.

Revit Project Base Point and Survey Point

Note that in the above example the Survey Point was unclipped and moved to the Station ‘ST1’. You could also leave the Survey Point at 0,0,0 which would be the OS False Origin. You should never unclip and move the Project Base Point as this can affect IFC datum and coordination with other models.

Coordinates can be given from either the Project base point or the Survey Point. You will also have to multiply the Easting and Northing by 1000 to take into account the scale difference between the Survey (in Meters) and the Revit Project (in Millimetres).

AutoCAD Civil 3D Export to AutoCAD

The TIN Surface in AutoCAD Civil 3D is a special object that cannot be used easily in Revit. The solution is to export the AutoCAD Civil 3D surface as an AutoCAD drawing. This will result in 3D Faces which can then be used to build the Revit Topography.

Click the Application Button, then Export and then Export Civil 3D Drawing.

Civil 3D Export to AutoCAD

The Export Dialog Box will automatically add a prefix to the drawing name to identify this as an AutoCAD drawing.

Civil 3D Export Dialog Box

One the export has completed the TIN surface will be represented as AutoCAD 3D faces. Make a note of the Layer that the 3D faces are positioned as this will be needed when creating the Revit Surface.

C3D to AutoCAD 3D Faces

Delete all other information and just retain the 3D faces and the datum’s as shown in the image below. The datum’s are very important for the coordination of the model within Revit. Scale the AutoCAD model from the Origin 0,0,0 and set the scale factor to 1000 (scale from Metres to millimetres).

Isolated AutoCAD drawing with 3D Faces and Datums

Revit Topography

Start a new project using your template in Revit. Make sure you switch to the site plan as the view range primary top and cut plane will be set to 10,000 to allow you to see the topograpgy.

In the Visibility Graphics/Overrides dialog box make sure that the Project Base Point and Survey Point are visible.

Revit Visibility Graphic Overrides Site Category

Next you link the AutoCAD drawing into Revit. Make sure that you set the import units to custom factor = 1 to ensure that there is no scale change. Also bring the AutoCAD file in Centre to Centre.

Revit Link CAD File Settings

Once the AutoCAD file has been linked it is a good idea to set the Visual Style to Wireframe to allow you to see the Setting Out information through the 3D faces.

Revit Set Visula Style to Wireframe

Unclip the Survey Point and move to the Survey Station of your choice (In this case STN1). Note that you will need to unclip the Survey Point, move to the location and then clip the Survey Point. I would then suggest pinning the AutoCAD drawing along with the Project and Survey Points.

Revit Project Base Point and Survey Point

Your Model is now coordinated!

To create the Topography, make sure that you first set the category to visible. Click the Massing and Site tab and select the Toposurface Tool.

Revit Toposurface

Click the ‘Select Import Instance’ from the context menu and select the linked CAD file.

Revit Select Import Instance

Do make sure that you now select the Layer where the 3D faces (triangulation) are positioned. You will now have a Revit Toposurface with Identical triangulation to your AutoCAD Civil 3D model.

Revit Toposurface From Civil 3D

Hope this helps,

LawrenceH

AutoCAD 2D Drawings to Revit via Dynamo – The Smart Way!

Even though the majority of users are now firmly engrained with Autodesk Revit software we still have to rely on AutoCAD for things such as Architects drawings, surveys and sometimes to interface with our favourite structural analysis software not currently integrated with Revit. Rather than recreating this data we can simply reuse this by reading BIM data from AutoCAD! So what is this BIM data from AutoCAD I hear you ask! In the case of a survey you have a wealth of information that you perhaps didn’t realise. The below Revit Survey was created entirely from the AutoCAD 2D survey. Note that some of the points may be slightly inaccurate due to the position of the text but still better that no 3D survey!

revit-survey-from-autocad-2d-drawing

Let’s take a look at the example below. Here you can see a typical 2D AutoCAD drawing representing a survey. We have the levels, information relating to trees, concrete bases, survey pins as well as areas of water. Of course this information could simply be linked into a Revit model as a 2D drawing but we would be losing quite a bit of information if we took this approach.

autocad-2d-survey

If you LIST or review the Properties of an AutoCAD object in a drawing such as a tree this is quite likely to be a Block. The block often contains attributes that we can utilise in Revit as BIM data. In the below example I have selected a tree. The Properties that I have highlighted are going to be used to recreate these trees. Notice that the canopy dimensions are controlled by the Scale; this is a fairly common practice.

autocad-block-and-attribute-properties

I have then typed the command EATTEXT (Enhanced Attribute Extraction) which will allow the end user to select the relevant properties and attribute values and write these out as a Microsoft Excel file.

Here is the Dialog that allows the selection of an entity or block. In this case I am extracting the block , PTS-047 which are the trees

eattext-page-3

I then select the relevant information that I require. In this case the Position (X,Y) and the scale (This is the canopy diameter) and the attributes.

eattext-page-4-selecting-required-properties

Here is the preview of the data prior to saving as a Microsoft Excel file. In this dialog you can drag the columns to new positions and suppress items such as name and count.

eattext-page-5

The data is now written to the Microsoft Excel file so that Revit and Dynamo can read this data and create the relevant objects.

autocad-extracted-data

In a similar way you can extract the text for the Level data and build a topographic surface in Revit. In the below image you can see the insertion point of the text as well as the Contents which will become the Z level. The trees are then placed as families which will automatically ‘sit’ on top of the topography.

properties-of-the-text-level

Here is the Dynamo Script to get the Topographic points from AutoCAD and create topography in Revit. It is worth noting that for those of you that have access to AutoCAD Civil 3D this can be achieved automatically. Note that I have split the image into two so that I could fit it on the screen!

dynamo-script-for-2d-levels-to-topography-part1

dynamo-script-for-2d-levels-to-topography-part2

Here is the resulting Topographic surface in Revit.

revit-topo

And here is the finished Topo with trees, slabs and sub regions imported.

revit-survey-from-autocad-2d-drawing

This workflow can be used for all manner of tasks. I do plan to create a full video tutorial if there is enough interest from the community?

Hope this is interesting,

LawrenceH

Revit 2013 to AutoCAD Civil3D

Over the last few weeks I have been asked about integration between Revit Structure and Civil 3D and Bentley MX and what can be transferred from each platform. I thought I would update you all on the various workflows that are available and how you can effectively use civil surfaces, alignments and corridors within Revit Structure. Below is a sample model I have been working on to test workflows, coordination and structures in Revit. I have made use of the bridge modelling toolkit and adaptive components for lighting and parapets.

The key tool needed for the integration to work correctly is the Revit extensions available to all subscription customers. Once you have this installed you can use the Civil Integration tools to transfer TOPO surfaces, corridors and alignments.

In the below example I have Civil 3D installed and the drawing open but if you do not have Civil 3D then you will need a LandXML file which contains all the relevant information such as the surfaces, corridors etc.

I have then run the Civil 3D integration as shown below and transferred the surfaces and corridor models to Revit Structure 2013. It is worth noting that you can only transfer one surface at a time but can of course run the integration multiple times to bring in other required corridors and surfaces.

You can also update and refresh the Revit model from Civil 3D and, if required transfer the bridge structures back into Civil 3D or to Navisworks for further coordination.

I do plan to provide a YouTube tutorial on this subject and deal with more examples of interaction with Civil 3D and Bentley MX.

Hope this helps,

LawrenceH