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AlPhuket13 post(s)
#23-Jun-15 06:02

Hi All,

I've managed to get QGIS working with a new "proj" file, but would far prefer to use Manifold, if I can get it to deal with the following CRS:

Spheroid name: Everest 1830

Semi major axis: 6 377 276.344999999700000000

Semi minor Axis: 6 356 075.413140240100000000

Inverse flattening: 300.801699999999980000

Mapping datum name: Everest 1830

WGS84 to Indian 1960 datum: Molodensky Transformation

dX -298.96

dY -750.02

dZ -249.84

rX 0

rY 0

rZ 0

ds 0

Coordinate System Lambert - single parallel at 26° N

Projection name: Lambert Conical

Zone: India 2A

Central meridian: 74° East

Latitude at origin: 26° North

Longitude at origin: 74° East

Scale factor at Central Meridian: 0.998 786 408

False easting: 2743196.4

False northing: 914398.8

Units: Meters

Sample conversion:

WGS84 latitude 25° 16' 14.2982" N

WGS84 longitud 71° 43' 36.3202" E

WGS84 elevation 17.703

Local datum latitude 25° 16' 13.5365" N

Local datum longitud 71° 43' 38.0616" E

Local datum elevatio 63.449

Local datum grid easting 2514568.726

Local datum grid northing 835666.249

As I understand it, I need to create an XML file (or two) to define the Datum and Projection, but my background is not in surveying or Cartography. Any help will be most appreciated.

Andy Sims56 post(s)
#26-Jun-15 11:15

The CRS looks like Kalianpur 1880 / India zone IIa EPSG 24372 which is defined in Indian Yards. The Manifold default "India" datum is fractionally different from your transforms, but all the other parameters can be set up without a custom preset: you select Conic/Lambert Conformal Conic (Single Parallel) and enter your values. If you use the Manifold India Datum, the XY/geographicals result for your sample will be off. If you want to be correct to the 4th DP of the geographicals then you can create a "Customs datums and CRS.xml" file to add to the Manifold config directory (if there is already one, add the <datum> section to the existing entries. I've attached a relevant file plus a .map with various drawings based on your sample: I started with the Local point data and transformed back to WGS84. You will need the custom datum in the config directory for this .map to work (and Manifold will need restarting if it was open when you copied in the xml file).

Not checked the heights and pretty sure that Manifold considers everything to be on the reference ellipsoid.

As always, check, check and check again: I may have got this wrong!

Attachments:
thread127313.zip

AlPhuket13 post(s)
#27-Jun-15 06:32

Thank you very much, Andy! As soon as I have a few minutes, will give it a try - I truly appreciate your help with this - CRS conversions are a new thing for me in GIS, and seemed a lot easier to do in QGIS (proj4 vs XML), except that most of what I do in GIS is database join related and that's a lot easier for me in Manifold.

I'll let you know how it goes, later. Thanks again!

volker

1,086 post(s)
#25-Sep-15 08:05

My Problem:

i always work mith Manifold's Projection:

But for this Projection there is no SRID in SQLServer:

The http://spatialreference.org/ref/epsg/31467/ only have the EPSG Code 31467 what`s the Datum of DHDN without South.

That`s a different between 2-3m from DHDN to DHDN South.

What to do ?


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