Projection Issues (Converting from UTM Zone 44N to Kandawala SriLanka Grid) shifting around 200 meters in the easting

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08-04-2014 12:24 AM
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New Contributor III

Hi,

I am from Sri Lanka. Northern Sri Lanka is in UTM Zone 44. If the data been collected in UTM Zone 44N and If I (or someone) convert it to Kandawala Sri Lankan Grid (Available in ArcGIS 10.1 as Projected Coordinate Systems -> National Grids -> Asia -> Kandawala Sri Lanka Grid) there seems to be shifting around 200 meters on the east. However if I use DNR GPS software from DNRGPS Application: Minnesota DNR load the shape file  then if I set (from the DNR GPS) the file -> Set Projections -> Datum as Kandawala and Projection as Sri Lankan Grid only few meter difference which is acceptable. I have verfied this with 2 Garmin GPS one set to UTM Zone 44n and other set to Sri Lankan Grid . I shall be thankful if I can sort out the issue in ArcGIS.

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6 Replies
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MVP Esteemed Contributor

This type of shift is normally associated with a datum shift.  Are you sure that the datums are the same?

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New Contributor III

Dear Dan Patterson,

No. The datum UTM Zone 44n is WGS84 while for Kandawala Sri Lankan Grid Datum is Kandawala. Geotrans software NGA: (U) MSP GEOTRANS 3.4 Geographic Translator (UNCLASSIFIED) also provide resonably accurate transformation.

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MVP Frequent Contributor

Did you set a transformation (datum shift) under the cords tab in the data frame properties page?

You have a single geocentric transform available (ArcGIS v10.2) for WGS84 to/from Kandawala, dx, dy, dz parameters -97.0, 787.0, 86.0.

That will be the likely cause of your 200m shift.

Neil

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New Contributor III

Dear Neil Ayres,

Many thanks for the reply. You may have a look at the original gpx via https://onedrive.live.com/embed?cid=45B0A8A523ED0470&resid=45B0A8A523ED0470%21585&authkey=ADgKMvA2w_... file from the garmin etrex10 GPS (with GLONASS enabled)  that can easily open dnr gps and save as a a arcgis shaefile from there.

I set the data frame properties to Kandawala Sri Lankan Grid

I have added the layer which was set at UTM Zone 44n with WGS 84datum.
When I added it gave Grographic Coordinate System Warning which is given belowGeographicSystemWarning.png

I have clicked the TransformationGeographicTransformation_ResultsWrongOne.png

If I simply click Convert from GCS_WGS_1984 to GCS_Kandawla and click ok results around 200m shifting in the east as I mentioned via a screenshot above. However if I choose using (choices are sorted by suitability for the layer's extent) using geocentric transoformation geocentric transformation it works and the answer is quite close. GeographicTransformation_Looksalright.png

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MVP Frequent Contributor

Rangunathan,

exactly,

you have to chose the correct transformation.

If this is has answered your problem, please mark the post as such.

N

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Esri Contributor

I've moved your post into the GIS Mapping Data space. GeoNet Help is intended for discussion on the community help and feedback. I have also added in a few additional tags. You can see more on the community structure, and what topics are under each space from the
following documents:

GeoNet Community Structure

ArcGIS Discussion Forums Migration Strategy

Thanks!

Don

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