A TopoSurface can be quickly generated from information from a surveyor, but only if provided in either of the two formats described below.
A POINTS FILE or TRIANGLE CAD FILE (TIN) will generally produce a more accurate TopoSurface, but only if there are enough points and they reasonably spaced.
But a 3D CONTOUR file is less likely to give you problems as the data has already been processed into a viable surface (by the CAD program).
If your site is largely covered with buildings a POINTS FILE would be preferable to 3D CONTOURS.
It is important you have contours or points beyond the edge of the area you want to create a TopoSurface for so the edges are accurate.
This becomes critical if there are not many points along the edges or contours are far apart.
POINTS FILE
A points file is typically generated by a civil engineering software application. The file provides contour data using a regularized grid of elevation points.
The points file must contain x, y, and z coordinate numbers as the first numeric values in the file. The file must also be in a comma-delimited file format (a CSV or TXT file).
Excel truncates a CSV to 62,000 points. If there are more points splitting it into two or three files will make it more manageable.
Additional information in the file (such as a point name) is ignored.
Any additional numeric information for a point must occur after the x, y, and z coordinate values.
If the file contains 2 points with the same x and y coordinates, Revit Architecture uses the point with the largest z value.
Revit CANNOT handle the following events:
- use of any other formatting (with different separators)
- use of points in thousands (100,000 instead of 100000)
- use of any descriptions or point numbers in front of, or after the point coordinates
- blank fields (for example when the z-value is 0)
- a separator at the end of the line (after z-value)
Example:
The below points/coordinates will create a 10x10 meter squared topo, with the cornes elevated to 0.3, 0.6, 0.9 and 1.2 meters. (if imported with millimeters as the unit format)
0,0,300
10000,0,600
0,10000,900
10000,10000,1200
TRIANGLE or MESH CAD FILE
Revit can use 3D mesh data imported in DWG, DXF, or DGN formats. This mesh may be a Triangle file (TIN) from the surveyor, or it could be a CAD mesh export from Rhino, 3DMax or Google Earth.
Revit Architecture analyses the 3D mesh data and creates the toposurface by placing elevation points at each vertex.
3D CONTOURS
Revit can use 3D contour data imported in DWG, DXF, or DGN formats.
This data must be made of continuous lines placed at their Z value in the CAD file.
RRevit Architecture analyses the 3D mesh data and creates the toposurface by placing a series of elevation points along the contour lines, so it is not as accurate as data from a POINTS FILE.