Coordinate Reference System Transformations. This is a .NET library implemented with F#, but also usable from C#. Most of the test code is actually written with C#. The third-part libraries used from the F# code may also have been implemented with C#.
License: MIT License
Hello!
I found wierd issue with ProjNet and hope you can shed some light on it. I checked sources of crsTransformations, there is .csv file with WKT strings assigned to EPSG codes. In code you get WKT string by code (SridReader.fs) and use ProjNet classes to create CoordinateSystems and calculate result (CrsTransformationAdapterProjNet.fs).
In my project I have many coordinate systems without EPSG codes, so I use ProjNet with WKTs and calculate result. It gives correct result when I transform GEOCS to PROJCS, but if I try to calculate between GEOCS to GEOCS, I receive results with mistake ~100 meters.
Consider code (dead simple):
string ProjSk42 = " GEOGCS[\"Pulkovo 1942\",DATUM[\"Pulkovo_1942\",SPHEROID[\"Krassowsky 1940\",6378245,298.3,AUTHORITY[\"EPSG\",\"7024\"]],TOWGS84[23.92,-141.27,-80.9,0,0.35,0.82,-0.12],AUTHORITY[\"EPSG\",\"6284\"]],PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",\"8901\"]],UNIT[\"degree\",0.0174532925199433,AUTHORITY[\"EPSG\",\"9122\"]],AUTHORITY[\"EPSG\",\"4284\"]]";
string ProjWgs84 = "GEOGCS[\"WGS 84\",DATUM[\"WGS_1984\",SPHEROID[\"WGS 84\",6378137,298.257223563,AUTHORITY[\"EPSG\",\"7030\"]],AUTHORITY[\"EPSG\",\"6326\"]],PRIMEM[\"Greenwich\",0,AUTHORITY[\"EPSG\",\"8901\"]],UNIT[\"degree\",0.0174532925199433,AUTHORITY[\"EPSG\",\"9122\"]],AUTHORITY[\"EPSG\",\"4326\"]]";
CoordinateSystemFactory qq = new CoordinateSystemFactory();
var wgs= qq.CreateFromWkt(ProjWgs84);
var sk42 = qq.CreateFromWkt(ProjSk42);
CoordinateTransformationFactory ctfac = new ();
ICoordinateTransformation trans = ctfac.CreateFromCoordinateSystems( wgs,sk42);
double[] fromPoint = { 66, 76 };
double[] toPoint = trans.MathTransform.Transform(fromPoint);
I tried many WKT strings, get them from your CSV, from epsg.io etc. Your lib uses same ProjNet classes:
let crs = _coordinateSystemFactory.CreateFromWkt(wellKnownText)
let trans: ICoordinateTransformation = ctFact.CreateFromCoordinateSystems(sourceCrs, targetCrs)
let result: double[] = trans.MathTransform.Transform(xy)
So I dont understand why ProjNet gives me bad result while crsTransformations works great. Maybe you have some ideas about it? I even checked binary content of ProjNet.dll, it's same for both cases :/ I answered this question here and got answers that ProjNet is outdated.
Also a suggestion, can you provide a feature to construct coordinateSystem from WKT ?
Hello. I am transforming coords from WGS 84 to Russian local systems (like EPSG:28406 Pulkovo 1942 / Gauss-Kruger zone 6).
I noticed that ProjNet4GeoAPI returns result which differs from EPGS calculations for about 70 meters or so. CrsTransformationAdapterDotSpatial saves the day and calculates exactly how EPGS.
code:
int epsgWgs84 = EpsgNumber.WORLD__WGS_84__4326;
//59°59'28.428" 30°45'16.428"
CrsCoordinate crsCoordinate = CrsCoordinateFactory.LatLon(59.991230000, 30.754563333, epsgWgs84);
var crsTransformationAdapter = new CrsTransformationAdapterProjNet4GeoAPI();
CrsTransformationResult centralStockholmResultSweRef = crsTransformationAdapter.Transform(crsCoordinate, 28406);
Console.WriteLine(centralStockholmResultSweRef.OutputCoordinate); //6374685.338621391 6655336.4426284255
var crsTransformationAdapter2 = new CrsTransformationAdapterDotSpatial();
centralStockholmResultSweRef = crsTransformationAdapter2.Transform(crsCoordinate, 28406);
Console.WriteLine(centralStockholmResultSweRef.OutputCoordinate); //6374811.1527767507 6655337.1512627564
epsg gives 6374811.15 and 6655337.15
So why ProjNet4GeoAPI differs so much?
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