You have a scanned image of a Contour Plan, and you want to convert that raster image into useful vector data. How do you go about it?
In the past, I would have used vanilla AutoCAD to trace the contours to polylines, then I might 'spline' them, then convert back to polylines (using a LISP tool), set all the elevations properly, and then import to Revit, then Create from Import to make the Topography. Fun!
However, this week I have fallen in love with a new tool. Its called AutoCAD Raster Design. I'll admit - it's not perfect. But it is smart, and it makes the process much more bearable. Just follow these steps: