hi there again
i did an dxf import into blender. everything works fine. but now i would like to apply some specific blender functions like subdevide or similar, but it doesn’t work as there are no meshes but only single triangle surfaces ( a lot of them represent my ground mesh object e.g.).
so here’s my question, can i “glue” these triangles together , so that i get meshes i can edit?
One guess would be to go into EditMode, select all the vertices with AKEY then do WKEY -> remove doubles. Any luck?
it works 
thank you broken[/i]
one more question concerning this topic:
when i want to smooth my landscape mesh using subsurf, all “edges” of my mesh get smoothed too. is there a way to define edges that should stay “sharp”. as example: in my modell the landscape has two parts. the street is one mesh, and the surrounding another. if i subsurf my surrounding mesh it doesn’t fit anymore with my street mesh.
I’m not really sure, but maybe you can try subdividing those edges endlessly (well, just a lot would be okay), and it’ll be less rounded there. There’s probably a better and easier way to do it, but I have no idea what that could be…
if you have two edges very close together, the smoothing effect of the subsurf won’t be quite so strong. To get a sharp edge, you can select the edge, extrude it, but keep it in the same place (overlapping the original vertices). That way, the edges are very close together and should create a sharp edge.
broken:
i think i understand what you mean, but it doesn’t work. e.g. if i try it with a subdevided simple plane (subdevide two or three times) than i choose the points at the outside, extrude them to the same position. when i now subsurf it will still get still very rounded. (it’s no difference with extrusion or without) 
where am i wrong?
When you subsurf, smooth, setsmooth or subdivide there’s no law that says you have to apply it to the whole mesh.
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hi fligh,
that would be nice: being able to just subsurf parts of a mesh. But I can’t find out how to do it! When ever I select just some vertices of a mesh, and click subsurf, it applies it to the whole mesh.
Is it really possible to do this?
cheers
btw - I tried the extrude trick and it does work, but only if you extrude only 1 edge (i.e. just two vertices) at a time. If you have lots of “edge” vertices it could take some time to do I guess. But still a very helpful trick to learn for me though!
I really don’t know what it is you are trying to do. But let’s assume you have a large plane that is subdivided many times to make a landscape. You want to make a mountain ? use the PET (proportional editing tool) to select only the verts you are working on and displace them. Make a road ? select all the verts in the road and use the numbers (N) to level the verts. And this you do for all the features you want to build.
Then you select the mountain and hit ‘Smooth’ in edit buttons to smooth it off. Want to mix the surface of the road up a little ? use noise. Want subtle noise ? select only the verts of the road and do (W) Subdivide-Fractal or subdivide, texture, noise.
OK, now the part I don’t understand… All you have done will be distorted, diluted, disfigured (whatever word you choose) if you now go and subsurf, because subsurf creates a new mesh using the shortest smooth distances between your old verts. ?Que paso? I want a road to look like blacktop and not like chocolate and I want the rocks in the mountain to look like rocks not like icecream. So if you want to smooth some part of a mesh select only those parts and if you need to subsurf seperate, extrude the edges, join and subsurf. But this way you will still end up with wrinkles at the corners.
Subsurf is generally usefull for hollow, organic meshes, not planes (except maybe windshields and such). If you need a subsurfed feature on a landscape make another subsurfed mesh with the same material and plop it where you want it even if it sticks out the bottom of your original mesh. This whole 3D thing is an optical illusion and the only important thing is what the viewer sees, not how you got there. Subsurf slows things down, especially on big meshes and I just don’t think it’s necessary most of the time.
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Correct on 3 counts, but wrong for subsurf
fligh %
the point is, that i created my modell in another tool and imported it via dxf (see start of this topic). that’s why i can’t use all the features blender has, while creating the modell.
now i try to discribe what the modell looks like: it’s a landscape surrounding an building. this building is not a fictive one but a real project. that’s why i can’t modell a landscape like i want it to look like, but like it is. to do so i created the landscape “layer” by “layer”, each of them 0,5m heigh (following the lines on the plan). These layer form my landscape like you would do it in a real modell.
but now i want to try using the subsurf function to smooth these “steps”. so that i get a more natural smoothed landscape rather than this modell style landscape.
you see? any other idea than subsurf?
Philip:
In the strictest sense correct but:
select only those parts and if you need to subsurf seperate, extrude the edges, join and subsurf
thirdsense:
Use BB to select the edges of two layers where they meet. Select all of the loops (rows of verts) where you want the profile to change (not just the two loops that are the edges of the two layers. In edit buttons hit ‘smooth’ a few times till they level off. You can also do this progressivly… select 4 loops and smooth, select 8 loops, the original 4 included, and smooth, 16 loops and smooth.
Or use another mesh, or a duplicated piece of an existing mesh (so you can join it and remove doubles) and stick it in there like landfill.
Or delete the loops that make these horrible transitions, add a circle, delete half the verts. Shape the remaining verts to the profile you want and position the end verts to correspond with the left-hand end verts of the two meshes. Then extrude to the right to the next two verts on and on and fill in the gap between the two meshes. Add a texture, hit noise, join the three meshes and remove doubles and recalc normals.
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what I would do is this:
From all these plateaus take only the top planes or the bottomplanes, Delete al other vertices and faces of the mesh, join the vertices in the diferent plateuas, such that you get lines that are almost perpendicular to the original heightlines in the newely formed plane that defines your desired surface.
A very quick way could be to use the “subdivide smooth” function (W-key --> subdivide smooth) instead of subsurface. The subdivide smooth function takes the curvature of your landscape mesh into account - in a way, somehow %| . The outcome depends a bit on the details of your mesh, though.
For a wide-meshed mesh, start with a low percentage of the subdivide smooth function and use a higher value (or 100%) for a second subdivision - if necessary.
Fore a close-meshed mesh, one time with 100% should be enough.
thank you for all these replies. there is a lot to learn for me.
i still must check some of them, but i think i just found an easy solution myself.
remember the problem where the “steps” in my modell. to erase these i can use the remove doubles function. it fits the two points together and “smoothes” the landscape (i just have to increase the distance value) 
it’s not perfect and i still have to try some more settings, but it’s the right way i think.