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All Blog Articles, Data Models and Free Source Code by Simon Greener, The SpatialDB Advisor is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.

SQL Server Spatial: Converting a LineString to COGO XML

Tuesday June 26 2018 at 16:58

KeywordsLineString COGO bearing distance export XML
Summary

Function to create Xml document containing Cogo bearing and distance instructions from an existing linestring.

I have just written a useful function for my new package of TSQL functions for SQL Server Spatial called STLine2Cogo which converts (exports) a (Multi)LineString into a set of instructions (bearing, distances etc) that can be shared with other COGO functions.

The function’s documentation can be seen at this STLine2Cogo

Here are some examples:

  1. -- Write 2D with DMS string bearings
  2. SELECT [cogo].[STLine2Cogo] (
  3.           geometry::STGeomFromText('LINESTRING (10 10, 8.163 17.034, 158.755 35.432, 157.565 25.108)',0),
  4.           CHAR(176),CHAR(39),'"')
  5. GO
  1. <Cogo srid="0">
  2.   <Segments>
  3.     <Segment>
  4.       <MoveTo>POINT (10 10)</MoveTo>
  5.       <DegMinSec> 345°21'48.75"</DegMinSec>
  6.       <Distance>7.26992</Distance>
  7.     </Segment>
  8.     <Segment>
  9.       <DegMinSec>  83° 2'4.652"</DegMinSec>
  10.       <Distance>151.712</Distance>
  11.     </Segment>
  12.     <Segment>
  13.       <DegMinSec> 186°34'30.73"</DegMinSec>
  14.       <Distance>10.3924</Distance>
  15.     </Segment>
  16.   </Segments>
  17. </Cogo>
  1. -- Write decimal degrees bearings and maintain 3D.
  2. SELECT [cogo].[STLine2Cogo] (
  3.           geometry::STGeomFromText('LINESTRING (10 10 -1, 8.163 17.034 0, 158.755 35.432 2, 157.565 25.108 5)',0),
  4.       NULL,NULL,NULL)
  5. GO
  1. <Cogo srid="0">
  2.   <Segments>
  3.     <Segment>
  4.       <MoveTo>POINT (10 10 -1)</MoveTo>
  5.       <Bearing>345.364</Bearing>
  6.       <Distance>7.26992</Distance>
  7.       <DeltaZ>1</DeltaZ>
  8.     </Segment>
  9.     <Segment>
  10.       <Bearing>83.0346</Bearing>
  11.       <Distance>151.712</Distance>
  12.       <DeltaZ>2</DeltaZ>
  13.     </Segment>
  14.     <Segment>
  15.       <Bearing>186.575</Bearing>
  16.       <Distance>10.3924</Distance>
  17.       <DeltaZ>3</DeltaZ>
  18.     </Segment>
  19.   </Segments>
  20. </Cogo>

The following code converts the shown LineString to a table of COGO values.

  1. SELECT [cogo].[STLine2COGO](geometry::STGeomFromText('LINESTRING (382.875 -422.76, 381.038 -415.726, 531.63 -397.328, 530.44 -407.652, 543.796 -406.729, 542.673 -415.759, 603.73 -415.063, 603.693 -403.377, 614.665 -404.601, 612.239 -376.561, 617.793 -375.878)',28356),
  2.                             NULL,NULL,NULL) AS t
  3. GO

The result is:

  1. <Cogo srid="28356">
  2.   <Segments>
  3.     <Segment>
  4.       <MoveTo>POINT (382.875 -422.76)</MoveTo>
  5.       <Bearing>345.364</Bearing>
  6.       <Distance>7.26992</Distance>
  7.     </Segment>
  8.     <Segment>
  9.       <Bearing>83.0346</Bearing>
  10.       <Distance>151.712</Distance>
  11.     </Segment>
  12.     <Segment>
  13.       <Bearing>186.575</Bearing>
  14.       <Distance>10.3924</Distance>
  15.     </Segment>
  16.     <Segment>
  17.       <Bearing>86.0467</Bearing>
  18.       <Distance>13.3879</Distance>
  19.     </Segment>
  20.     <Segment>
  21.       <Bearing>187.089</Bearing>
  22.       <Distance>9.09956</Distance>
  23.     </Segment>
  24.     <Segment>
  25.       <Bearing>89.3469</Bearing>
  26.       <Distance>61.061</Distance>
  27.     </Segment>
  28.     <Segment>
  29.       <Bearing>359.819</Bearing>
  30.       <Distance>11.6861</Distance>
  31.     </Segment>
  32.     <Segment>
  33.       <Bearing>96.3654</Bearing>
  34.       <Distance>11.0401</Distance>
  35.     </Segment>
  36.     <Segment>
  37.       <Bearing>355.055</Bearing>
  38.       <Distance>28.1448</Distance>
  39.     </Segment>
  40.     <Segment>
  41.       <Bearing>82.9893</Bearing>
  42.       <Distance>5.59584</Distance>
  43.     </Segment>
  44.   </Segments>
  45. </Cogo>

A final test it to convert a line to Cogo and then create the line from that Cogo.
They should be the same:

  1. WITH line AS (
  2.   SELECT geometry::STGeomFromText('LINESTRING (10 10 -1, 8.163 17.034 0, 158.755 35.432 2, 157.565 25.108 5)',0) AS line
  3. )
  4. SELECT a.line.STEquals(
  5.         [cogo].[STCogo2Line] (
  6.           [cogo].[STLine2Cogo] (a.line,CHAR(176),CHAR(39), '"'),
  7.           3, 2
  8.         )) AS isEquals
  9.   FROM line AS a
  10. GO
  11. isEquals
  12. --------
  13. 1

I hope this is of interest to someone.

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