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!
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.
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.
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
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.
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.
The data is now written to the Microsoft Excel file so that Revit and Dynamo can read this data and create the relevant objects.
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.
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!
Here is the resulting Topographic surface in Revit.
And here is the finished Topo with trees, slabs and sub regions imported.
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,