Revit - Import Revit Topography from 2D CAD Survey
Posted by Kent Watson on 13 October 2014 05:10 PM
Tip Title: Import Revit Topography from 2D CAD Survey
Author: Glenn Sinclair – Technical Consulting Lead
A topography need to be created but the only survey information is a 2D CAD file.
Ideally topography information would be provided with topo lines at the correct height in 3D (Z axis), if however this information cannot be sourced, it may be possible to extract the X,Y,Z information from the 2D survey and use this to automatically create the topography in Revit.
This depends on the method used to show the heights in the survey CAD file, if the objects used to display this information are attributed blocks, where the origin of the block is at the correct X and Y coordinates, and the Value of the attribute contains the height. (If plain text is used it may be able to be used but the X and Y coordinates may not be entirely accurate).
Attributed block displaying height.
The majority of this solution occurs in AutoCAD, to prepare the information for Revit, Open the CAD file received.
It is important to check the units of the CAD file, ensure the X and Y coordinates are in meters, and the value in the block is also in meters.
The AutoCAD command to extract this information is EATTEXT, that stands for Extract ATtribute TEXT. This brings up the attribute extraction wizard:
An extraction template will need to be saved for the first time, this can be re-used.
Choose whether to extract info from one or multiple files, in this case it is the current file only.
Choose the object types to extract info from, displaying blocks with attributes only narrows this down.
Choose which properties of the object you wish to extract, in this case it is only Attribute and Geometry categories, PositionX, PositionY and the attribute (H).
The count and name colmuns are not needed, the xolumns can be re-ordered by dragging to get X, Y, Z in order
This information can be output to a .CSV file ready to be imported into Revit.
In Revit go to Massing and Site tab > Topo Surface > Create from Import > Specify points file and browse to the .csv file. Ensure the Units are correctly set.
A warning will appear that Some rows could not be imported, this is generally referring to the header rows in the .csv file, this .csv file can be opened in Excel for checking.