topic Re: Mesh from 3D contour DWG? in Modeling

Mesh from 3D contour DWG?

Thomas Holm — Tue, 23 May 2023 15:03:16 GMT

Talking about curved cliffs...

I just got this 3D contour DWG file from a local planning office.

I imported it as an object. As you can see there are no surfaces, just contours, and they aren't even contiguous.

Now I wonder if anyone's got a good idea on how to make an Archicad mesh out of this?

Or am I better off using the conventional procedure of creating the mesh in plan from the 2D contours?

Re: Mesh from 3D contour DWG?

Anonymous — Fri, 25 Jan 2008 19:21:49 GMT

I like to create them from 2d lines, I have never seen 3D contours like that before and wouldn't even know where to start. So, I am no help at all.....

Re: Mesh from 3D contour DWG?

Anonymous — Fri, 25 Jan 2008 19:22:43 GMT

What kind of planning office gives you a 3D contour????

Re: Mesh from 3D contour DWG?

Thomas Holm — Sat, 26 Jan 2008 11:37:54 GMT

In Sweden, when you want to build something, it's a requirement by law that you draw your site plan on an official 'New building map' that you have to order from the local planning office.

But there are no standards- Every city, county or municipality seems to do their own thing. Most (not all) can deliver them digitally, usually in DWG or DXF format, and some of them have even started to deliver 3D information in various ways.

In Autocad, there are 3D surface entities that Archicad understands, like 3D Face, 3D Polyface or Polygon mesh. Archicad's translator can make 3D meshes out of those.

But this particular county has decided to just deliver level info by drawing contours as a normal polyline with a height value (z coordinate). Perhaps there are Autocad applications that can utilize this in a meaningful way, but I don't know.

Also, If you look at the picture you will see that all the borders and building info on the map (well, almost - it's not consistent) lies flat on the zero z. This means I wouldn't see that if I create a surface mesh from the 3D contours.

To me this looks just like a political gimmick - 'look, we use the latest technology, we can deliver 3D maps' - usefulness isn't as interesting to them. But I may be wrong, I was actually hoping to be, if someone here could tell me how to use this!

Re: Mesh from 3D contour DWG?

Eduardo Rolon — Sat, 26 Jan 2008 12:57:20 GMT

IME the Z coordinate is created by the software that civil engineers use to establish the contours and 9 times out of 10 they have no idea the lines are floating in space. The easiest way to create a mesh out of this is to get it into SketchUp and use its mesh command. Though I still prefer the "traditional" linked method.

Re: Mesh from 3D contour DWG?

Thomas Holm — Sat, 26 Jan 2008 14:28:11 GMT

Didn't think of Sketchup. I'll try that! thanks!

Re: Mesh from 3D contour DWG?

Djordje — Sat, 26 Jan 2008 17:28:39 GMT

Thomas wrote:
Now I wonder if anyone's got a good idea on how to make an Archicad mesh out of this?

Did you try ArchiTerra? I would.

Re: Mesh from 3D contour DWG?

Thomas Holm — Sat, 26 Jan 2008 20:27:26 GMT

Well Sketchup didn't cut it. I went into Sketchup Pro 6 and used its Create Sandbox from contours command, and the mesh created looked good in Sketchup, but when saved as DWG and opened as object in Archicad, I found that Sketchup doesnt create any of the entities that Archicad can convert to an Archicad mesh. The file consists of lines and individual triangle surface polygons. It looks OK as a surface but can't be used for SEOs. When exploded, all surfaces vanish, only 2D lines left.

Architerra and I have a severed relationship. I bought it for AC10 but I never managed to make it work for me. It works for itself, on its own terms, but for me it's like fitting a square peg into a round hole. Also, the version update delay, the (for me) incomprehensible manual and the fact that its creations don't work fully without the updated application installed into the current AC version rules it out for me.

So I guess I'm back at square one!

Re: Mesh from 3D contour DWG?

vfrontiers — Sun, 27 Jan 2008 17:26:56 GMT

I have always promoted RE-CREATING contours from DWG as their resolutions seemed to always be 1 point every 2 or 3 inches! This will absolutely kill your rendering / 3d window times and is senseless as a topographic map is an ESTIMATION anyway.

Simply tracing the 2d version and adjusting heights would probably take only 30min(or less) on your site. You could probably work the math out to pay for itself in 10 3d views or so.

Using some creative SEO techniques (discussed elsewhere on this forum) will let you cut in roads and pads pretty easily.

My $.02...

Re: Mesh from 3D contour DWG?

Karl Ottenstein — Sun, 27 Jan 2008 18:13:00 GMT

vfrontiers wrote:
I have always promoted RE-CREATING contours from DWG as their resolutions seemed to always be 1 point every 2 or 3 inches! This will absolutely kill your rendering / 3d window times and is senseless as a topographic map is an ESTIMATION anyway.

Simply tracing the 2d version and adjusting heights would probably take only 30min(or less) on your site. You could probably work the math out to pay for itself in 10 3d views or so.

My experience too, although some mountainous lots may take an hour.

My additional 2 cents:

With Virtual Trace in 11, it is easier than with ghost stories in prior versions for this kind of thing since the Trace Reference can be a Worksheet with an xref to the dwg, so no need to create a fake story for the dwg or come up with strange layer combos to accomplish your work since the active and trace can have different layer settings.

Also, use a Reference Level (Preferences) so that you can enter your z-heights using exactly the surveyor numbers and not have to do any math in your head. 😉

Nonetheless, it would be nice if there was an easy way to convert the 3D contours into an actual AC mesh. (I've only had one surveyor produce these, and I did go the SketchUp route with it...but it was limited, as Thomas notes, and so I ended up making the mesh myself.)

Cheers,
Karl

Re: Mesh from 3D contour DWG?

Dwight — Sun, 27 Jan 2008 18:51:26 GMT

And further, many more facets can be dropped if you create a subjective site form related to a grid estimation system rather than replicating contours.

I place a grid over a contour plan with smaller grids where contours are critical and larger grids where they don't. With this method, you pay attention to important outcroppings and cliffs, but smooth over the rest.

Re: Mesh from 3D contour DWG?

Thomas Holm — Sun, 27 Jan 2008 20:17:12 GMT

Thanks for all advice!

As you may have noticed, I've collected a number of links on how to simplify a contour map and create a mesh from it, and also how to manipulate it with SEOs here. It just that I was hoping for a shortcut this time

Karl wrote:
With Virtual Trace in 11, it is easier than with ghost stories in prior versions for this kind of thing since the Trace Reference can be a Worksheet with an xref to the dwg, so no need to create a fake story for the dwg or come up with strange layer combos to accomplish your work since the active and trace can have different layer settings.

Karl, do you mean that a DWG Xrefed into a Worksheet doesn't add its layers to the project, or should I trace a worksheet from another project file this way?

Re: Mesh from 3D contour DWG?

Karl Ottenstein — Sun, 27 Jan 2008 20:33:27 GMT

Thomas wrote:
Karl, do you mean that a DWG Xrefed into a Worksheet doesn't add its layers to the project, or should I trace a worksheet from another project file this way?

Nothing that dramatic. Just that until 11, only stories could be ghosted, so you had to put the xref on a story for tracing purposes and now you can use an independent worksheet. The layers come in, but as you know, in 11, they are grouped below all user layers, and they do purge properly if you detach the xref later.

Yeah, to trace from another project, you'd have to use Laci's trick and place a view of the dwg from the other project onto a layout and then use the layout as the trace reference.

Cheers,
Karl

Re: Mesh from 3D contour DWG?

Thomas Holm — Sun, 27 Jan 2008 20:58:25 GMT

OK Karl, I thought I'd missed something really important here. I've never used worksheets for that. But since I'll want to plot the imported map along with my project, I might just as well place the Xref on a floor plan storey anyway.

Re: Mesh from 3D contour DWG?

Karl Ottenstein — Mon, 28 Jan 2008 00:14:31 GMT

Thomas wrote:
OK Karl, I thought I'd missed something really important here. I've never used worksheets for that. But since I'll want to plot the imported map along with my project, I might just as well place the Xref on a floor plan storey anyway.

Not sure why? You can 'plot' a worksheet as easily as a story, right?

Karl

Re: Mesh from 3D contour DWG?

Thomas Holm — Mon, 28 Jan 2008 06:51:39 GMT

Well, I have a habit of using a storey below the lowest floor for site and ground work. I realise I can use a worksheet as well, but since it's only 2D I'd need to place my site mesh on that low storey anyway. So why complicate things by xrefing the dwg into a worksheet instead of into this floor plan directly?

Re: Mesh from 3D contour DWG?

Karl Ottenstein — Mon, 28 Jan 2008 17:26:26 GMT

Thomas wrote:
Well, I have a habit of using a storey below the lowest floor for site and ground work. I realise I can use a worksheet as well, but since it's only 2D I'd need to place my site mesh on that low storey anyway. So why complicate things by xrefing the dwg into a worksheet instead of into this floor plan directly?

I did it that way, too, until 11 arrived. I just find it easier now to not have to deal with the xref layers in my layer combos for that site story... and for turning them on/off to trace contours onto the mesh. For me, Virtual Trace of a Worksheet is easier - no template (combo) modifications regardless of the engineer who produced the dwg, easier (IMHO) tracing / visual comparison, and switch trace with active for quickly jumping back and forth between the survey worksheet and my sitework.

Nothing too significant though...mostly just work preference. 😉

Cheers,
Karl

[Edit: typos]

Re: Mesh from 3D contour DWG?

Thomas Holm — Mon, 28 Jan 2008 23:05:58 GMT

Guess I'm just being conservative

Thanks Karl!

Re: Mesh from 3D contour DWG?

Anonymous — Tue, 29 Jan 2008 09:40:55 GMT

Hi folks,

For site survey I've created a special layer combo and 2 associated layers that works like sweet..
I called the layer combo "Temporary" and a layer "Temp_on" and another "Temp_off".
The layer Temp_on is always locked and visible in all other layer combos that I have.
Each and every dwg/dxf/jpg that I use to help the design I put it grouped in the Temp_off layer.
Every time I need to use one of them (i.e. create the mesh with the dwg survey) I activate the Temporary layer combo
and it hides all other layer except for the Temp_on and Temp_off.
Then I change the object/drawing/image layer from Temp_off to Temp_on.
When I go back to the Design layer combo there it is! The survey dwg locked just to help the mesh design.