How do you share surfaces with LDT users?

[Sinc]

We've just gotten a request for a DTM that can be used in Land Desktop. By DTM, they mean points, breaklines, and boundaries. How do we give that to them?

Surfaces do not seem to be stored correctly in XML files. Instead of exporting the defining elements of a surface - i.e. the points, breaklines, and boundaries - the XML seems to contain a bunch of points, followed by a series of triangle definitions. The triangle definitions describe how the points should be connected to form a TIN.

When the other company pulls the XML into Land Desktop, they get a surface that contains all the TIN triangles, but it does not contain the boundary. We can also extract the boundary from the surface and send that to them, and they can manually add the boundary after importing the XML. But this since this surface basically has a breakline along every edge of every TIN triangle, it does not respond to edits the same way as a surface defined from points and breaklines would.

We've been somewhat stumped on how to extract JUST THE BREAKLINES from a surface in C3D, so they can build the surface they want. Anyone know how? And most importantly, anyone know an EASY way to send surface points, breaklines, and boundaries to a LDT user, so they can build a REAL surface?

[nzeeben]

Open the drawing in LDT Companion

Under the projects pulldown.

Extract Civil 3D Data.

It will populate a Land Desktop project based on the information in the dwg file.

Zip and ship it to your client.

Nick

[Anonymous]

Your TIN (triangles) is a product of your breaklines, points and whatever else you have used to create the surface. If you use a non-destructive breaklines for your boundaries the triangles are reformed to match the boundary. Whatever format you use (e.g. 3D faces) to export the TIN, it should represent your surface adequately without having to include any additional breaklines or other information. The client shouldn't muck with the triangles.

[Sinc]

I'll give that a try.

I don't suppose there's any chance we'll ever get a user-friendly way of doing this, e.g. an "eTransmit to Land Desktop" function that would create a zip file containing drawings and Land Desktop project without requiring me to startup Land Desktop myself?

[Sinc]

Is it possible to create an LDT surface from the triangles?

I tried extracting the TIN triangles from a surface, but then I could not find any easy way of creating a surface in LDT from the 3D Faces. Was I overlooking something?

[mjfarrell]

In terrain model explorer...create a new surface, and add the faces under AutoCAD Objects,

although what part of exporting the DEM directly in C3D isn't working as expected in LDT?

[alberto_go]

XML my friend.... use XML format.... once surface is created as as XML, In Land Desktop you just import that in...

AG
Phoenix, AZ

[Sinc]

Hmmm.... Can't find that option. I see a "Drawing Objects" option in the surface definition in C3D, but not in LDT Terrain Explorer.

I wasn't trying to export a DEM (which in my mind is an evenly-spaced horizontal grid with elevations...?). I was actually just trying to export the points, breaklines, and boundaries. LandXML surface imported into LDT do not include the breaklines or boundary. Instead, it is just a collection of TIN triangles, and LDT adds garbage triangles to the edges.

There is some question as to whether the client actually needs points and breaklines instead of TIN triangles. But sending the XML evidently was not good enough. I assumed this was because they really wanted the actual breaklines, and not just a bunch of triangles. Of course, an export with just Points, Breaklines, and Boundaries is not really sufficient, either, because that would not include any surface edits such as flipped triangles (although I don't think there were any in this particular case). So this might be another case where the LandXML really IS good enough, it's just that the recipient doesn't know what LandXML is. We get that a lot.

[Sinc]

Before someone else tells me to send them the LandXML, please read my first post in this topic... Thanks.

[Anonymous]

TME->Surface->TIN Data->Point Files, right-click, select Add Points from
AutoCAD Objects select the type of object.

wrote in message news:5675206@discussion.autodesk.com...
Hmmm.... Can't find that option. I see a "Drawing Objects" option in the
surface definition in C3D, but not in LDT Terrain Explorer.

[Anonymous]

Hi Sinc,

You can add 3D faces to an LDD surface data set and the vertices of the face
get added to the model as Points. If, as any one would expect, you want the
3D face sides to be added to the model as breaklines, you are out of luck.
LDD does not recognise the sides.

Hence, in LDD, if you don't write code to do it follow this procedure:

Start the Region command and select the 3D faces to convert them to regions.
Explode the regions,
Use Map drawing cleanup to delete duplicate objects
Add the remaining 3D lines to the model as breaklines.

However, if you are starting in software such as Civil 3D, the optimum
method is via LandXML.

--

Laurie Comerford
CADApps
www.cadapps.com.au
www.civil3Dtools.com
wrote in message news:5675159@discussion.autodesk.com...
Is it possible to create an LDT surface from the triangles?

I tried extracting the TIN triangles from a surface, but then I could not
find any easy way of creating a surface in LDT from the 3D Faces. Was I
overlooking something?

[Anonymous]

Hi Sinc,

If you send the raw data to build a DTM to a client instead of the DTM, make
sure you write the contract absolving you of ALL RESPONSIBILITY for the DTM.


--

Laurie Comerford
CADApps
www.cadapps.com.au
www.civil3Dtools.com
wrote in message news:5675206@discussion.autodesk.com...
Hmmm.... Can't find that option. I see a "Drawing Objects" option in the
surface definition in C3D, but not in LDT Terrain Explorer.

I wasn't trying to export a DEM (which in my mind is an evenly-spaced
horizontal grid with elevations...?). I was actually just trying to export
the points, breaklines, and boundaries. LandXML surface imported into LDT
do not include the breaklines or boundary. Instead, it is just a collection
of TIN triangles, and LDT adds garbage triangles to the edges.

There is some question as to whether the client actually needs points and
breaklines instead of TIN triangles. But sending the XML evidently was not
good enough. I assumed this was because they really wanted the actual
breaklines, and not just a bunch of triangles. Of course, an export with
just Points, Breaklines, and Boundaries is not really sufficient, either,
because that would not include any surface edits such as flipped triangles
(although I don't think there were any in this particular case). So this
might be another case where the LandXML really IS good enough, it's just
that the recipient doesn't know what LandXML is. We get that a lot.

[Sinc]

Of course. Why put it in a place that's easy to find? Gotta love that user-friendly Autodesk Software... (or go insane, one of the two)

[Sinc]

This looks like it creates a surface that is identical to the one that gets created by using LandXML. At least, I see no breaklines in the surface. It looks like it simply pulls in a TIN, just like LandXML. Is that correct?

Also, I'm assuming we must use LDT 2008 in order to extract data from C3D 2008 objects. Will LDT 2008 also extract entities from C3D 2007 drawings?

All in all, this looks like the best method. We can export the DWG to Autocad, letting C3D flatten everything and get rid of all the C3D entities. Then we can also extract the data into a project. Then send the client both the Exported drawing and the zipped project.

That seems to be a whole lot easier than constantly explaining how to use LandXML, then suffering the wrath of the client who does not want anything to do with LandXML and blames us for making their life difficult, which is what usually happens when LandXML comes up. True, LandXML may be simple enough, but for users who are still using R2000 software and maybe 10% of Land Desktop's capabilities, avoiding LandXML and giving them their old comfortable LDT project is by far the easiest course.

And as I've said before, when clients get data in a format they are not familiar with, they automatically assume it's bad data, and they stop using us as a survey firm. That's something we can't afford. So if we have to go through the pain of starting up Land Desktop, extracting data into the LDT project, exporting a file to Autocad 2007, and then sending all that to the client, that's better than having them assume we're giving them garbage because they don't know what a .XML file is.