[LandXML] LandXML-1.2 schema has begun

  • From: "Nathan Crews" <nathan.crews@xxxxxxxxxxx>
  • To: <landxml@xxxxxxxxxxxxx>
  • Date: Tue, 22 May 2007 10:23:32 -0600

2007 has brought ever broadening adoption and use of LandXML as a survey
data standard. Current efforts are focused on proposed and as-built road
surveying and construction; requiring slight modification to the survey data

In late 2006 the US Transportation Research Board published the results of
the TransXML project. LandXML-1.1 was formally adopted as the US
Transportation Design/Survey standard (see
http://onlinepubs.trb.org/onlinepubs/nchrp/nchrp_rpt_576.pdf for details).
In addition the US Federal Aviation Administration (also part of US Federal
DOT) is undergoing LandXML-1.1 adoption for Airport Surveys. 

As part of this standards adoption process we continue to evaluate existing
survey software to assess the extent of LandXML data import/export support.
To date, most of these applications fall short of working with LandXML raw
and reduced survey data; we need to do better. Examples of the survey data
in question can be found on the
-1.1> http://www.landxml.org/LandXMLSamplesDemos.aspx page in the
LandXML-1.1 column.

We really need the survey hardware and software application vendors to
review these proposed changes closely. 


LandXML-1.2 draft schema:


Here are the proposed changes so far:

LandXML-1.2.xsd Schema Changes since LandXML-1.1.xsd (working draft date May
22, 2007)

Summary of Changes


1.      Added survey level loop and DOT road survey attributes to
<RawObservation>, <ReducedObservation> and <ReducedArcObservation>.
2.      Created <TestObservation> and added to

Schema Change Details


Added survey level loop and DOT road survey attributes to <RawObservation>,
<ReducedObservation> and <ReducedArcObservation>

<RawObservation> and the new <TestObservation> element are derived from a
new complex base type called <RawObservationType>. In order to support
common road survey work the following attributes were added to
<RawObservationType> base type.


Added 3-wire level loop attributes: 

*       "upperStadia" is the upper stadia hair rod reading.
*       "rod" is the middle hair rod reading. 
*       "lowerStadia" is the lower stadia hair rod reading. 
*       "circlePositionSet" represents the position of the reading circle.
This optional attribute (assumed to be "1.0"), unless multiple reading
circle positions were present from the same setup record.
*       "alignRef" is the name of the alignment. 
*       "alignStationName" is the station value where the rod reading is
*       "alignOffset" is the signed (+/-) distance from the CL of the
referenced alignment.


"alignRef", "alignStationName", and "alignOffset" attributes have also been
added to <ReducedObservation> and <ReducedArcObservation> elements with the
same meaning.

Created <TestObservation> and added to <InstrumentSetup>.<Corrections>

The new <TestObservation> element is derived from and extends
<RawObservationType>, adding the "setup1RodA", "setup1RodB", "setup2RodA"
and "setup2RodB" attributes; all defined as numeric double precision rod
height readings. This captures calibration data required for high accuracy
level loop elevation calculations.


As always, comments and your time are much appreciated.


Best Regards,

Nathan Crews



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