landxml import and alignment parameter constraints

[Buzz0m]

Hi y'all!

Soo... I've been using landXML export for some while now but when I've tried to import alignments to Civil3d the results have been less than flattering. The problem seems to be that Civil interprets the three coordinates specified (for curves) in an xml-file as the "three point"-definition for a curve instead of "start point, center point, end point" as defined in landXML 1.2 schema. This leads to various problems...

Does anybody know if this is a settings issue? What should I tweek to get this to work?

Here is the link to landXML 1.2 schema which indicates that curves should be defined by start center and end points:

http://www.landxml.org/schema/landxml-1.2/documentation/LandXML-1.2Doc_Curve.html

And I'll attach a few screenshots illustrating the problem:

1. Desing view of the alignment. As you can see there is atleast one curve which makes an almost complete circle. Civil interprets the "center point" as one of the "three points" needed to define an arc, but still takes in account the rotation direction ("cw") and thus does NOT draw the curve through the point which originally was intended as the center point...
2. panorama (alignment grid view) view. Curves seem to be defined by three points, instead of start, end and center point, which isn't an option when you unlock the "parameter constraint lock" and try to change the "parameter constrain" from the dropdown menu.

[Buzz0m · Accepted solution]

In case anyone ever stumbles upon this problem I'm pleased to write, that we solved it. It seems that when exporting geometry from designenvironment to another (this case microstation -> citycad -> civl3d) with landxml there is a loss of data in the sense that coordinates are rounded to something like 4 decimalplaces. The needed accuracy for Civil to get the alignment imported correctly was in my case 7 decimalplaces.

We also discovered a problem with how landxml codes vertical curves (profile). The radius of a curve is always supposed to be positive when importing to Civil3d. Otherwise you will get an error like "cannot solve vertical curve in <profile> <0> at station... Imported as a straight segment.". This error was in my case caused by an implemented landxml definition called InfraModel3 (IM3). In this format the radius of curves is given a negative or positive value depending on it beeing a sag or crest curve.

Cheers!

[fuzz2112]

So how did you fix it

[Buzz0m]

I asked for a more precise definition (this was a setting in the native design environment) of the alignment geometry and then manually altered the radius curves of the profiles with a text editor (eg. notepad). This can be done by changing the .xml file-extension to .txt and when your are done change it back to .xml. Another way is to use a html editor, which can open an .xml-file. For firefox there is a add-on called firebug or something like that which is fairly simply and nice to use...

It should be noted that C3d doesn't support Inframodel3-format, so try using landxml1.2 if possible...