Activity Feed › Discussion Forums › Strictly Surveying › Machine Control with Leica Equipment
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Peter Kozub, post: 421610, member: 375 wrote:
I built a basic surface in 2016 C3D
flipped a few triangles
added a box to make more triangles too
then used the same box to punch a hole in the surface for a swimming pool etc.XML this surface to Surveyor plus running 5.02 SurvCe and the hole is filled in
I see and understand the nature of this example problem. However, I don’t believe this to be the fault of the LandXML data per se… rather, I believe it to be a result of an inconsistent implementation between technology providers on how to interpret and/or represent the data and/or provide the necessary tools for the users to develop the intended data in the form required by the technology application(s).
In this example, it would be my understanding that the surface you intended to provide would have a “hole” in it with what I’d refer to as null information (for the benefit of other readers, please note that a “null” value is different than a value of “0”) within the hole. From what I’m able to determine from the
portion of the example, you have included four triangle definitions with the “i” flag (invisible) set to 1 (True) (bolded for emphasis): [INDENT]
15 9 8
16 9 15
16 12 11
16 14 12
14 13 12
16 15 14 [/INDENT]The question I’d tend to ask is “If an object is flagged as invisible, is it (or should it be treated as) null?” I suspect the answer you’d get would be dependent upon whom you asked.
From the SurvCE side of this discussion, I suspect the Carlson algorithm is seeing the four triangle face definitions in the file, is ignoring the “invisible” tag simply building a surface model from the available
collection of data. As a side note, I was provided the following by one of the Carlson SurvCE/SurvPC programming team members last night: [INDENT]Carlson SurvCE/SurvPC 6.x will have the same number of options (including “skip invisible triangles” controls), as the Carlson Office Software.
In meanwhile, please export from AutoDesk Civil 3D [just] the TIN definition and no invisible triangles, etc.[/INDENT]From the Civil 3D side of this discussion, I suspect extraneous or superfluous information is being generated (intentionally or not) that serves no real purpose. One solution (as cited above) would be to investigate whether or not C3D can be instructed to not include invisible triangle definitions when a LandXML surface file is being generated. As [USER=7109]@squowse[/USER] pointed out:
[INDENT]”If I delete triangles in my software then they don’t appear in the XML at all.“[/INDENT]
Peter Kozub, post: 421610, member: 375 wrote:
The EDIT history is not being applied even thou it is in the XML file
i seriously doubt that ANYONE’S XML import can support all the edit history items in C3D feature lines, paste, Flip, move etc its endless…I don’t believe LandXML was ever intended to support “history” (revision) items. It is my understanding that LandXML data is merely a “snap-shot in time” of the data being provided. For example, if I were a field-based contractor whose sole responsibility is/was to build or grade the surface given to me, I could care less what kinds of historical manipulations went into the creation of that surface. In fact, I probably wouldn’t want access those previous revisions for fear of building the wrong thing. However, if I were a designer whose job is/was to build the surface for a given project site, having the ability to historically track the surface creation process may be of interest to me (in my opinion, I’d prefer my source data for the surface to be accurate for the model I intend to produce). Regardless of LandXML’s (in)ability to handle “history” or data revisions, LandXML provides value to the market precisely because it is an open and defined standard and can survive the test of time.
Peter Kozub, post: 421610, member: 375 wrote:
So the best way is to remove the edit history on C3D objects by exploded them to 3D faces and feature line and gradeing objects to 3D polys
and import as simple DXF.I find this approach to be a potential source of error as it relies on the recipient (and/or the recipient’s technology application) to faithfully reproduce from graphical form what the underlying open data file format is trying to convey. The problem is that not all applications are able to use the graphical data. For example, applications may not understand the “ever-changing” DXF file format, 3DFACE objects, 3D polylines, proprietary “smart” objects, etc. In fact, it reminds me of a conversation from another board back in 2010 that is still pertinent today.
Regardless, individuals should work closely with their clients and technology partners in an effort to produce and migrate data with minimal loss of integrity and in a form most suitable to their needs. I do thank you for sharing your insights and observations.
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Dxf is pretty reliable too. Also readable in a text editor but not nearly as easy to read (by a human) as an xml.
I think the problem arises with C3D’s more powerful surface options. When you delete part of a surface it does not permanently delete the triangles. It is then outputting this “history” to the xml. And we have established that at least survce is not taking notice of this inner voiding boundary. Forewarned forearmed.
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https://forums.autodesk.com/t5/autocad-civil-3d-forum/xml-export/td-p/6410159
Here’s a discussion on the Civil 3D forum on this matter.
Seems C3D includes the deleted triangles in the xml but with an “i=1” code in front of them. No way to tell C3D to exclude these so you’d have to go through and delete them from the xml yourself which is obviously ridiculous if you have a large surface and numerous deleted triangles.
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Rusty, post: 421971, member: 9889 wrote: https://forums.autodesk.com/t5/autocad-civil-3d-forum/xml-export/td-p/6410159
Here’s a discussion on the Civil 3D forum on this matter.
Seems C3D includes the deleted triangles in the xml but with an “i=1” code in front of them. No way to tell C3D to exclude these so you’d have to go through and delete them from the xml yourself which is obviously ridiculous if you have a large surface and numerous deleted triangles.
Or maybe export to dxf then reimport.
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squowse, post: 422052, member: 7109 wrote: Or maybe export to dxf then reimport.
That would just give you 3D faces when you open the dxf
Doesn’t really solve the xml triangle issue.
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Rusty, post: 422207, member: 9889 wrote: That would just give you 3D faces when you open the dxf
Doesn’t really solve the xml triangle issue.
I was thinking that you could create a surface in c3d from the dxf? So that the boundaries etc are burned in. If there was no proper command for it.
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squowse, post: 422240, member: 7109 wrote: I was thinking that you could create a surface in c3d from the dxf? So that the boundaries etc are burned in. If there was no proper command for it.
When you create the surface from the 3d faces it creates triangles across the deleted areas again.
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Invisible triangle just does not make sense to me. Seems to me it could make reference to an interior feature or triangle. Bentley InRoads will use the term “interior” feature to indentify closed areas that are not to be triangulated. Such as buildings and ponds.
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Rusty, post: 422387, member: 9889 wrote: When you create the surface from the 3d faces it creates triangles across the deleted areas again.
Wow that is surprising.
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