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Author Topic: change higt system on and crate local projektion coordinatsystem  (Read 712 times)

nils-erik

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I need help to change the prj file. i donĀ“t know how i whrite the kods.

If you look on the koordinats you see the diff in the higt. in the pjr file i have a gieod swen 17 rh 2000 or change to rh 00.


next question are do a tranformations prj fil from (Transformation file form Trimble gnss hand computer) wgs84 to Aitik and i this skrip are right higt in.

PP ATIK LOKALA                                                        Sweref 992015 RH2000                       Diff
                    x          y             z                                              X                   Y               Z           Z
PP1              384.872   2 879.73   373.828      PP1           7 442 783.35   173 244.99   374.734      0.906
PP2              124.11     2 862.74   365.793      PP2           7 442 742.47   172 986.90   366.699      0.906
PP8           5 289.24           7 496.59   474.219      PP8           7 439 360.78   179 045.99   475.125      0.906
PP9           5 531.56           7 522.74   471.79      PP9    7 439 388.67   179 288.10   472.696      0.906
PP14   5 354.91           7 341.76   457.443          PP14        7 439 526.27   179 075.93   458.349      0.906
PP32   8 387.23           6 617.33   343.245          PP32        7 440 901.05   181 874.00   344.151      0.906
PP33   8 271.25           6 642.75   345.792         PP33     7 440 850.69   181 766.47   346.698      0.906


Prj file

COMPD_CS["Aitik",
PROJCS["SWEREF99",
GEOGCS["SWEREF99",
DATUM["SWEREF99",
SPHEROID["GRS 1980",6378137,298.257222101,
AUTHORITY["EPSG","7019"]],
TOWGS84[0,0,0,0,0,0,0],
AUTHORITY["EPSG","6619"]],
PRIMEM["Greenwich",0,
AUTHORITY["EPSG","8901"]],
UNIT["degree",0.01745329251994328,
AUTHORITY["EPSG","9102"]],
AUTHORITY["EPSG","4619"]],
PROJECTION["Hotine_Oblique_Mercator",
AUTHORITY["EPSG","9812"]],
PARAMETER["latitude_of_center",67.0590952],
PARAMETER["longitude_of_center",20.880526911],
PARAMETER["azimuth",77.850696],
PARAMETER["recitified_grid_angle",0],
PARAMETER["scale_factor",1.0000380561],
PARAMETER["false_easting",5461.66],
PARAMETER["false_northing",-9470162.166999999],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]]],
VERT_CS["swen17_rh2000",
VERT_DATUM["swen17_rh2000_",2005],
UNIT["metre",1,
AUTHORITY["EPSG","9001"]]]]


Transformation file form Trimble gnss hand computer
<?xml version="1.0" encoding="utf-8"?>
<JOBFile jobName="Zone Site Aitik Lokala 0909" version="5.2" product="Coordinate System Manager" productVersion="3.7.1.0" TimeStamp="2021-10-01T19:25:46" xsi:schemaLocation="http://www.trimble.com/schema/JobXML/5_2 http://www.trimble.com/schema/JobXML/5_2/JobXMLSchema-5.2.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <FieldBook />
  <Reductions />
  <Environment>
    <CoordinateSystem>
      <SystemName>Site</SystemName>
      <ZoneName>Aitik Lokala 0909</ZoneName>
      <DatumName>Datum from data collector</DatumName>
      <Ellipsoid>
        <EarthRadius>6377397.155</EarthRadius>
        <Flattening>0.00334277316935</Flattening>
      </Ellipsoid>
      <Projection>
        <Type>TransverseMercator</Type>
        <Scale>1</Scale>
        <CentralLatitude>0</CentralLatitude>
        <CentralLongitude>20.3082777777777</CentralLongitude>
        <FalseNorthing>0</FalseNorthing>
        <FalseEasting>1500000</FalseEasting>
        <GridOrientation>IncreasingNorthEast</GridOrientation>
        <SouthAzimuth>false</SouthAzimuth>
        <ApplySeaLevelCorrection>true</ApplySeaLevelCorrection>
      </Projection>
      <LocalSite>
        <Type>Grid</Type>
        <ProjectLocationLatitude />
        <ProjectLocationLongitude />
        <ProjectLocationHeight />
      </LocalSite>
      <Datum>
        <Type>SevenParameter</Type>
        <GridName>Datum from data collector</GridName>
        <Direction>WGS84ToLocal</Direction>
        <EarthRadius>6377397.155</EarthRadius>
        <Flattening>0.00334277316935</Flattening>
        <RotationX>0.00023623840803</RotationX>
        <RotationY>0.00050479016227</RotationY>
        <RotationZ>-0.00218395708080</RotationZ>
        <TranslationX>-419.37502063361995</TranslationX>
        <TranslationY>-99.352022523247</TranslationY>
        <TranslationZ>-591.34897364935</TranslationZ>
        <Scale>1.0000009949609898</Scale>
      </Datum>
      <HorizontalAdjustment>
        <Type>NoAdjustment</Type>
      </HorizontalAdjustment>
      <VerticalAdjustment>
        <Type>NoAdjustment</Type>
      </VerticalAdjustment>
      <CombinedScaleFactor>
        <Location>
          <Latitude />
          <Longitude />
          <Height />
        </Location>
        <Scale />
      </CombinedScaleFactor>
    </CoordinateSystem>
  </Environment>
</JOBFile>

Paulo

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Re: change higt system on and crate local projektion coordinatsystem
« Reply #1 on: October 09, 2021, 07:57:02 AM »
Hi Nils erik,

I calculated by Least squares a 3d helmert similarity transformation from sweref99 2015 to Aitik Lokal using the first 6 points and got the  results seen in attachment.

The transformation is accurate to about 0.5 cm as seen by using estimated parameters to calculate coordinates of last point. The shift in 90 cm in Z between 2 CS must be some datum issue..

Definitely Aitik is based on some oblique Projection as seen from estimated Kappa of 77,27 deg...

If you need more help, you can send me a Personal message,


Best Regards,

Paul Pelletier,
Surveyor

Paulo

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Re: change higt system on and crate local projektion coordinatsystem
« Reply #2 on: October 11, 2021, 06:52:03 PM »
Hello again,

this time I was able to estimate a 7 parameter Helmert transformation between WGS84 datum (equivalent to Sweref99) and Aitik Lokala datum using the first 6 points you supplied in both Coordinate systems. I did it supposing Aitik Lokala coordinates are based on an Oblique Mercator projection (as defined earlier) with Bessel 1841 reference elipsoid. The results are very good as shown in attachment where I transform the Aitik coordinates of these 7 points into Sweref99 2015 RH2000 using these 7 parameters (TOWGS84) and accuracy is at the mm level...

Looks good :)
Best Regards,

Paul Pelletier,
Surveyor