Robert,
OK, I've got to jump in here.
First of all, I appreciate the effort you and your staff expend in continuing to improve the product. For example, the improvements made to the Landmark user interface found in Vectorworks 11, are certainly a step forward. I have found the interface easier to understand, and therefore quicker to perform the iterative process required to get a usable DTM.
Yet, I continued to have some difficulties so I gave tech support a call. The response I received gave me some insight on how to get the DTM tool to provide more accurate results. I was told that one will experience better results by converting the 2d contours to 3d polygons instead of using 3d loci. This was what I had been experiencing, but I though maybe I was doing something wrong.
What I would suggest while the users wait for an improved DTM generating algorithm, is for Nemetschek to be more clear in the supporting documentation about what input methodologies work best with the current algorithm. Specifically in this case, tech support admitted that one would get better results by converting 2d contours to 3d polygons, instead of using 3d loci.
For what it's worth I've never been able to get 3d loci to generate anything but a DTM with all sorts of bizarre contours. In addition, based on my conversation with tech support, I've confirmed that a more accurate and robust model can be generated by manually interpolating additional 2d contours as source data for the DTM algorithm. By robust I mean a model that more readily accepts site modifiers without generating bizzare results. Based on some of the other posts, I don't think my experience is unique, and I'm sure others would appreciate some additional clarity from Nemetschek in this regard.
Finally I appreciate your efforts to provide perspective on the situation by reminding us that "it's only dirt". Of course what we are really considering here is the accurate placement of dirt, not the dirt itself.
Overall, I'm very pleased with VW 11, I think it provides excellent "bang for the buck" and I look forward to experiencing the fruits of your labor - continued improvements to the product.
John Brubacher
Mac OS 10.3.4