Topography From Autocad Drawings?

[stusic]

Hey All,

I've got a site plan a client sent me and I need to convert that to a mesh. Is there an easy way to go about doing that? Although the site plan is in 3d, I think I will need to go into the drawing with Autocad and make closed polylines out of the topo lines, but after that I'm not sure. Any advice? I've posted the file if anyone wants to take a look.

[dellis]

Phillip,

I just selected the white contours and welded all the verts...then changed the verts to corner and added a terrain compound object to it. This is what i got:

[stusic]

My bad -- I should have cleaned up the drawing a bit before I posted it. Take a look at this file: I've got my contour data in, but in some areas, the terrain modifier doesn't flow nicely with the surrounding contours -- it'll drop to the "zero" elevation (mostly around the edges). I'm wondering if it's something I'm doing wrong... I just select the splines, then click on "terrain". Done.

[dellis]

I also moved the splines closer to the origin. It was really far away...and bad things happen all around when its that far. I would make some new spline connections where the terrain modifier is freaking out as well.

[stusic]

I just realized I didn't post the file, but it doesn't matter anymore; moving the splines closer to the origin helped a lot. I had just imported them into the scene and began working on them without paying attention to where they were. Thanks Dwayne.

[dellis]

No worries...glad to help!

[loydg]

Origin on MAX has always been an issue. My only caution in doing this is to make sure:

1) you move everything for the Max file at once
0r
2) move it in AutoCAD using a line from point A (in the model) to point B (origin).

I only bring this up since I've been burned on it several times when a client comes back with new data. :roll:

[dellis]

To avoid that problem i generally have the drafters put a point object somewhere in their drawing which acts as a common point for both of us should changes happen. Then i just create another point in MAX, align it to the common point, link everything to my point, then move my point to the origin. This way all you need to do when changes are made to the drawing then imported...you just align your point to the common point again and link the new stuff to your point and repeat the move back to the origin.

It would be cool if autocad had some form of linking similar to MAX since this would allow a really fast workaround to this problem. For instance, In the above situation, if everything in autocad was linked to the common point and then imported. You could align your max point to the common point, then link the common to the max point....then move it to the origin....then everything imported after that would snap right to its proper location since the hierarchical relationship would be established for position.

You can do this with merging files into MAX from other scenes if you have a common node that everything is linked to. MAX knows if there is a hierearchical relationship between objects if the names stay the same and it will prompt you, if you want to re-establish the link.

I hope this makes sense.

[dellis]

Now that i'm thinking about it....it would be cool to have this concept as a feature in the filie link manager. Like the ability to pick an object in the imported dwg which will represent the point you want to use to move the imported drawing to the origin. This would kill all the messing around in MAX!

[stusic]

Well, if the Autocad drawing was drawn at 0,0,0 (like it should be) you wouldn't have to do anything, correct?

Btw, I did as you suggested and put a point in the dwg and replicated it in max.

[stusic]

Okay, I'm getting frustrated. The terrain modifier doesn't work well at all. Is there another way to create terrain from topos? With the contours I have, there are areas that have a shear drop-off (along retaining walls, against buildings, etc), but the terrain object doesn't work well with these at all. I've tried to do what I can, but it doesn't seem to do the trick.

Man, I like flat sites. :roll:

[iamreavis]

Well, if the Autocad drawing was drawn at 0,0,0 (like it should be) you wouldn't have to do anything, correct?

Believe me, there is usually a reason for things to NOT be drawn at the origin in AutoCAD! I work in civil engineering and surveying, and we always have to put our drawings on State Plane coordinates, which are based on some arbitrary location in the state we are in, which is usually many miles from where the actual site is. Local governments require our work to be on this coordinate system so that their GIS departments can accurately relate locations of disparate projects to each other. If I'm drawing some piddly little detail or whatever, I'll put it near the origin because that's the base point for inserting it into another drawing as a block. You can have your CAD guys use the command WBLOCK to export the linework you need into its own special file and specify the origin to be near the center of the new file. This will resolve all of the issues I hear everyone complain about all the time.

I know this causes problems in Max, but it's easy enough to move whatever you need back to the origin instead of wasting time trying to deal with the errors it can produce because of rounding errors, etc.

Sorry for the rant, but you would not BELIEVE how many times a day I read a similar complaint on the many different forums I follow!

Peace!

[dellis]

Yeah....we have the same issues here. The survey data, generally, has to stay where its at. Thats why i was thinking that it would be nice to have the option to move everything inside the File Link Manager or the Importer. That way drafters don't have to worry about anything but drafting...and us on the viz side of things don't have to worry about changes after moving everything to the origin in MAX. I think its a fairly common issue...

[stusic]

Is there another technique I can use to get an accurate site surface? The Terrain object doesn't work, I haven't been able to get the Conform object to work... Any other ideas?

[dellis]

Well....there is a longer way to do it....Surface tools. You basically connect all the verts manually, building a spline cage and then add a surface mod. Might take awhile though. What is it about the terrain object thats not working? And what are you using the conform object for? Are you putting something on the surface terrain?

[stusic]

To use the surface tools, doesn't each elevation contour need to have the same number of vertices to be able to connect them?

Yep, I'm going to be adding condos, sidewalks, parking spaces, etc.

As far as Conform goes, I was just looking for something to get this accomplished while Terrain isn't working...

The terrain object's not working right because it doesn't seem to be accurate; there are places in the topography that go straight down, and the terrain object doesn't do that. Normally I just create my site as flat (or close to), but I can't this go around. The design of the buildings are dependent on the topography being accurate, as the buildings are 3-story on the uphill side and 4-story on the downhill side.

I attached some more screenshots, one of autocad, showing the area I'm having trouble with, and one of max, showing the same view with the terrain object on. Just ain't the same. I've looked at the topo over and over again, and it looks right to me. This is so incredibly frustrating. For a first time making a topo, this isn't going so well. I think it'd be okay for an abstract landscape, but doesn't seem so for something that needs accuracy.

[iamreavis]

This http://area.autodesk.com/index.php/forums/viewthread/14073/ sure looks like the same thread from the AREA (Autodesk's Max forum). There seems to be a solution at the end, but it doesn't look like it would be pleasant or easy to do this sort of thing frequently unless the poster finally gets around to writing his script...

[stusic]

This http://area.autodesk.com/index.php/forums/viewthread/14073/ sure looks like the same thread from the AREA (Autodesk's Max forum). There seems to be a solution at the end, but it doesn't look like it would be pleasant or easy to do this sort of thing frequently unless the poster finally gets around to writing his script...

Yep, that's my same thread -- I'm looking all around for a solution...

[iamreavis]

Can you post the CAD file for me to take a look at? I got the max file from the other forum but will have to look at them tonight at home.

[stusic]

Can you post the CAD file for me to take a look at? I got the max file from the other forum but will have to look at them tonight at home.

It's the same dwg from post #16 above.

[stusic]

This image is essentially what I have to lay on top of the topography, but, as of now, its sitting on a flat site.

[dellis]

I would probably just build the whole thing using surface tools. You could break it up a bit if you wanted though. You could connect those lines (vertical) that are getting messed by the terrain mod seperately. Then use the terrain mod on the rest and then attach them. I know its not an elegant solution but....

[stusic]

On some advice I got, I used the displacement modifier and a gradient image to get some definition. It works pretty well and it also allowed for a lot of flexibility in the amount of detail you want to show.

[cliff collins]

We use Revit to convert 3d contours from Autocad to a Toposurface.
Import cad into Revit, use Site tool Toposurface--click on imported cad file
and it creates a 3d toposurface.

Export FBX from Revit, import into Max, in a separate file called Topo_xref
Xref this max scene into a Master Max file.

Cheers........