marci002 / proj4dart Goto Github PK

Proj4dart is a Dart library to transform point coordinates from one coordinate system to another, including datum transformations.

License: MIT License

Dart 99.96% JavaScript 0.04%

dart crs proj4js proj4 gis wkt srs

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proj4dart's Issues

Accuracy issue from EPSG:26716 to EPSG:4326

I'm trying to transform from EPSG:26716 to EPSG:4326, and the results I get with proj4dart are slightly off.

Here's the code:

    final tuple = proj4.ProjectionTuple(
      fromProj: proj4.Projection.parse('+proj=utm +zone=16 +datum=NAD27 +units=m +no_defs'),
      toProj: proj4.Projection.WGS84,
    );

    final pointSrc = proj4.Point(x: 444650, y: 4640510);
    final pointForward = tuple.forward(pointSrc);
    print('Transform point ${pointSrc.toArray()} from EPSG:26716 to EPSG:4326: ${pointForward.toArray()}');

proj4dart gives [-87.66744437695456, 41.9143951210944]
while epsg.io gives [-87.6674992, 41.9165563]
cf https://epsg.io/transform#s_srs=26716&t_srs=4326&x=444650.0000000&y=4640510.0000000

The difference in latitude is particularly noticeable. Am I misusing the library?

flutter_map - Proj4Crs (Custom CRS) not works

Even if this is happening in a flutter_map project, I feel that it makes sense to post the issue here.

I am trying to load a WMS layer with a defined CRS. What I am doing is more or less:

    final resolutions = <double>[
      134217728, // 20
      67108864,
      33554432,
      16777216,
      8388608,
      4194304, //15
      2097152,
      1048576,
      524288,
      262144,
      131072, // 10
      65536,
      32768, 
      16384,
      8192,
      4096, // 5
      2048,
      1024,
      512,
      256, 
      128, // 0
    ];
    var crs = Proj4Crs.fromFactory(
        code: 'EPSG:3857',
        proj4Projection: projection3857,
        resolutions: resolutions);

    List<LayerOptions> layers = [
      TileLayerOptions(
        opacity: 1,
        backgroundColor: Colors.transparent,
        wmsOptions: WMSTileLayerOptions(
          crs: crs,
          transparent: true,
          format: imageFormat,
          baseUrl: _getCapabilitiesUrl,
          layers: [_layerName],
        ),
      )
    ];

But on creation of the layer, I am getting:

The setter 'z=' was called on null.
Receiver: null
Tried calling: z=null

with the following stacktrace:

The relevant error-causing widget was
    FlutterMap 
lib/…/core/onlinesourcespage.dart:216
When the exception was thrown, this was the stack
#0      Object.noSuchMethod  (dart:core-patch/object_patch.dart:53:5)
#1      Projection.transform package:proj4dart/…/classes/projection.dart:171
#2      _Proj4Projection.project package:flutter_map/…/crs/crs.dart:452
#3      WMSTileLayerOptions.getUrl package:flutter_map/…/layer/tile_layer.dart:262
#4      TileProvider.getTileUrl package:flutter_map/…/tile_provider/tile_provider.dart:20
...

Am I missing something in the creation?

Just as info, if it helps:

_getCapabilitiesUrl = http://geoservices.retecivica.bz.it/geoserver/ows?
_layerName = P_BZ_BASEMAP_HYBRID_EPSG3857

On a sidenote: when removing the crs option it works.

3857 to 4326 issue

Hi, I am sure I am doing something wrong here, but I can't find what and how, so after hours of trial, I will ask you to see if there is an issue. :-)

I am converting a 3857 bbox to 4326.

      var originPrj = proj4dart.Projection.parse(wktPrj);
      var destPrj = proj4dart.Projection("EPSG:4326");

      var ll = proj4dart.Point(x: west, y: south);
      var llDest = originPrj.transform(destPrj, ll);

where wktPrj is read from a prj file. That one is read properly and recognises the projection correctly (PseudoMercatorProjection).

But the converted Y for some reason is off.
For example converting:
west: 1235116.6370151439
south: 5852571.412104731

should give me:
x: 11.0952417
y: 46.4488475

but the y I get is:
y: 46.6408787

Do you have any idea what that might happen?

Custom crs for flutter_map wrong

Hello,
I have a problem with custom crs in flutter_map. Could you help me?

This is my code:

List<double> getResolutions(double maxX, double minX, int zoom, [double tileSize = 256.0]) {
  var size = (maxX - minX) / tileSize;
  return List.generate(zoom, (z) => size / math.pow(2, z));
}

int r = 6378137;
double _boundsD = r * math.pi;

final Bounds<double> _bounds = Bounds<double>(
  CustomPoint<double>(532687.840000, 1250489.697300),
  CustomPoint<double>(607009.080400, 1345845.903300),
);
final resolutions = getResolutions(607009.080400, 532687.840000, 19);
final maxZoom = (resolutions.length - 1).toDouble();

var def = '+proj=tmerc +lat_0=0 +lon_0=108.25 +k=0.9999 +x_0=500000 +y_0=0 +ellps=WGS84 +towgs84=-191.90441429,-39.30318279,-111.45032835,0.00928836,-0.01975479,0.00427372,0.252906278 +units=m +no_defs';

var epsg9217 = proj4.Projection.add('EPSG:9217', def);

var epsg9217CRS = Proj4Crs.fromFactory(
  code: 'EPSG:9217',
  proj4Projection: epsg9217,
  resolutions: resolutions,
  bounds: _bounds,
  origins: [CustomPoint(-5122600.0, 1.00011E7)],
);

In main FlutterMap:

FlutterMap(
  options: MapOptions(
    crs: Epsg3857(),
  ),
  children: [
                  TileLayerWidget(
                      options: TileLayerOptions(
                        backgroundColor: Colors.transparent,
                        wmsOptions: WMSTileLayerOptions(
                          crs: const Epsg3857()
                          version: '1.1.1',
                          transparent: true,
                          baseUrl: 'https://ows.terrestris.de/osm/service?',
                          layers: ["OSM-WMS"],
                        )
                      ))
  ],
  layers: [
    TileLayerOptions(
                          backgroundColor: Colors.transparent,
                          fastReplace: true,
                          wmsOptions: WMSTileLayerOptions(
                            crs: epsg9217CRS,
                            version: '1.3.0',
                            transparent: true,
                            baseUrl: <wms_server_url>,
                            layers: ['2,3'],
                          ),
                        ))
  ]
)

Layer 'OSM-WMS' is show on my application but layer ('2,3') is not.
I console url that generate by WMSTileLayerOptions but BBOX is not correct.
Log : 499804.8535484949, 10000988.210334396, 499804.8535484949, 10000988.210334396

In javascript project, I use proj4js and BBOX is correct.
Log in javascript: 582600.854078125, 1278053.6005968752, 583345.8244375, 1278798.5709562502
This is code of javascript:

<script src="https://cdn.jsdelivr.net/npm/[email protected]/dist/proj4-src.min.js"></script>
<script src="https://cdn.jsdelivr.net/gh/openlayers/openlayers.github.io@master/en/v6.6.1/build/ol.js"></script>

const newProjCode = 'EPSG:9217';
const def = "+proj=tmerc +lat_0=0 +lon_0=108.25 +k=0.9999 +x_0=500000 +y_0=0 +ellps=WGS84 +towgs84=-191.90441429,-39.30318279,-111.45032835,0.00928836,-0.01975479,0.00427372,0.252906278 +units=m +no_defs";
proj4.defs(newProjCode, def);
ol.proj.proj4.register(proj4);
		
const projection = new ol.proj.Projection({
            code: 'EPSG:9217',
            extent: [532687.8399999999, 1250489.6973, 607009.0804000003, 1345845.9033000004], // [540286.530000, 1276528.530000, 585024.462000, 1318764.630000],
            units: 'm',
});

Thank you.

P/S: This is my WMS Capabilities:

This XML file does not appear to have any style information associated with it. The document tree is shown below.
<WMS_Capabilities xmlns="http://www.opengis.net/wms" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:esri_wms="http://www.esri.com/wms" version="1.3.0" xsi:schemaLocation="http://www.opengis.net/wms http://schemas.opengis.net/wms/1.3.0/capabilities_1_3_0.xsd http://www.esri.com/wms https://localhost:6080/arcgis/services/Test_BD/BDN/MapServer/WmsServer?version=1.3.0%26service=WMS%26request=GetSchemaExtension">
<Service>
<Name>
<![CDATA[ WMS ]]>
</Name>
<Title>
<![CDATA[ Test_BD_BDN ]]>
</Title>
<Abstract>WMS</Abstract>
<KeywordList>
<Keyword>
<![CDATA[ ]]>
</Keyword>
</KeywordList>
<OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:type="simple" xlink:href="https://localhost:6080/arcgis/services/Test_BD/BDN/MapServer/WmsServer?"/>
<ContactInformation>
<ContactPersonPrimary>
<ContactPerson>
<![CDATA[ ]]>
</ContactPerson>
<ContactOrganization>
<![CDATA[ ]]>
</ContactOrganization>
</ContactPersonPrimary>
<ContactPosition>
<![CDATA[ ]]>
</ContactPosition>
<ContactAddress>
<AddressType>
<![CDATA[ ]]>
</AddressType>
<Address>
<![CDATA[ ]]>
</Address>
<City>
<![CDATA[ ]]>
</City>
<StateOrProvince>
<![CDATA[ ]]>
</StateOrProvince>
<PostCode>
<![CDATA[ ]]>
</PostCode>
<Country>
<![CDATA[ ]]>
</Country>
</ContactAddress>
<ContactVoiceTelephone>
<![CDATA[ ]]>
</ContactVoiceTelephone>
<ContactFacsimileTelephone>
<![CDATA[ ]]>
</ContactFacsimileTelephone>
<ContactElectronicMailAddress>
<![CDATA[ ]]>
</ContactElectronicMailAddress>
</ContactInformation>
<Fees>
<![CDATA[ ]]>
</Fees>
<AccessConstraints>
<![CDATA[ ]]>
</AccessConstraints>
<MaxWidth>4096</MaxWidth>
<MaxHeight>4096</MaxHeight>
</Service>
<Capability>
<Request>
<GetCapabilities>
<Format>application/vnd.ogc.wms_xml</Format>
<Format>text/xml</Format>
<DCPType>
<HTTP>
<Get>
<OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:type="simple" xlink:href="https://localhost:6080/arcgis/services/Test_BD/BDN/MapServer/WmsServer?"/>
</Get>
</HTTP>
</DCPType>
</GetCapabilities>
<GetMap>
<Format>image/bmp</Format>
<Format>image/jpeg</Format>
<Format>image/tiff</Format>
<Format>image/png</Format>
<Format>image/png8</Format>
<Format>image/png24</Format>
<Format>image/png32</Format>
<Format>image/gif</Format>
<Format>image/svg+xml</Format>
<DCPType>
<HTTP>
<Get>
<OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:type="simple" xlink:href="https://localhost:6080/arcgis/services/Test_BD/BDN/MapServer/WmsServer?"/>
</Get>
</HTTP>
</DCPType>
</GetMap>
<GetFeatureInfo>
<Format>application/vnd.esri.wms_raw_xml</Format>
<Format>application/vnd.esri.wms_featureinfo_xml</Format>
<Format>application/vnd.ogc.wms_xml</Format>
<Format>application/geojson</Format>
<Format>text/xml</Format>
<Format>text/html</Format>
<Format>text/plain</Format>
<DCPType>
<HTTP>
<Get>
<OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:type="simple" xlink:href="https://localhost:6080/arcgis/services/Test_BD/BDN/MapServer/WmsServer?"/>
</Get>
</HTTP>
</DCPType>
</GetFeatureInfo>
<esri_wms:GetStyles>
<Format>application/vnd.ogc.sld+xml</Format>
<DCPType>
<HTTP>
<Get>
<OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:type="simple" xlink:href="https://localhost:6080/arcgis/services/Test_BD/BDN/MapServer/WmsServer?"/>
</Get>
</HTTP>
</DCPType>
</esri_wms:GetStyles>
</Request>
<Exception>
<Format>application/vnd.ogc.se_xml</Format>
<Format>application/vnd.ogc.se_inimage</Format>
<Format>application/vnd.ogc.se_blank</Format>
<Format>text/xml</Format>
<Format>XML</Format>
</Exception>
<Layer>
<Title>
<![CDATA[ Layers ]]>
</Title>
<CRS>CRS:84</CRS>
<CRS>EPSG:4326</CRS>
<CRS>EPSG:0</CRS>
<CRS>EPSG:9217</CRS>
<!--  9217 is customized SR = PROJCS["VN2000",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",108.25],PARAMETER["Scale_Factor",0.9999],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]  -->
<EX_GeographicBoundingBox>
<westBoundLongitude>108.549444</westBoundLongitude>
<eastBoundLongitude>109.233283</eastBoundLongitude>
<southBoundLatitude>11.307092</southBoundLatitude>
<northBoundLatitude>12.170651</northBoundLatitude>
</EX_GeographicBoundingBox>
<BoundingBox CRS="CRS:84" minx="108.549444" miny="11.307092" maxx="109.233283" maxy="12.170651"/>
<BoundingBox CRS="EPSG:4326" minx="11.307092" miny="108.549444" maxx="12.170651" maxy="109.233283"/>
<BoundingBox CRS="EPSG:0" minx="532687.840000" miny="1250489.697300" maxx="607009.080400" maxy="1345845.903300"/>
<BoundingBox CRS="EPSG:9217" minx="532687.840000" miny="1250489.697300" maxx="607009.080400" maxy="1345845.903300"/>
<Layer queryable="1">
<Title>
<![CDATA[ bdn ]]>
</Title>
<Abstract>
<![CDATA[ ]]>
</Abstract>
<CRS>CRS:84</CRS>
<CRS>EPSG:4326</CRS>
<CRS>EPSG:0</CRS>
<CRS>EPSG:9217</CRS>
<!--  9217 is customized SR = PROJCS["VN2000",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",108.25],PARAMETER["Scale_Factor",0.9999],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]  -->
<EX_GeographicBoundingBox>
<westBoundLongitude>108.549444</westBoundLongitude>
<eastBoundLongitude>109.233283</eastBoundLongitude>
<southBoundLatitude>11.307092</southBoundLatitude>
<northBoundLatitude>12.170651</northBoundLatitude>
</EX_GeographicBoundingBox>
<BoundingBox CRS="CRS:84" minx="108.549444" miny="11.307092" maxx="109.233283" maxy="12.170651"/>
<BoundingBox CRS="EPSG:4326" minx="11.307092" miny="108.549444" maxx="12.170651" maxy="109.233283"/>
<BoundingBox CRS="EPSG:0" minx="532687.840000" miny="1250489.697300" maxx="607009.080400" maxy="1345845.903300"/>
<BoundingBox CRS="EPSG:9217" minx="532687.840000" miny="1250489.697300" maxx="607009.080400" maxy="1345845.903300"/>
<Layer queryable="1">
<Name>1</Name>
<Title>
<![CDATA[ Hành chính cấp xã ]]>
</Title>
<Abstract>
<![CDATA[ ]]>
</Abstract>
<CRS>CRS:84</CRS>
<CRS>EPSG:4326</CRS>
<CRS>EPSG:0</CRS>
<CRS>EPSG:9217</CRS>
<!--  9217 is customized SR = PROJCS["VN2000",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",108.25],PARAMETER["Scale_Factor",0.9999],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]  -->
<EX_GeographicBoundingBox>
<westBoundLongitude>108.549444</westBoundLongitude>
<eastBoundLongitude>109.233267</eastBoundLongitude>
<southBoundLatitude>11.307092</southBoundLatitude>
<northBoundLatitude>12.166196</northBoundLatitude>
</EX_GeographicBoundingBox>
<BoundingBox CRS="CRS:84" minx="108.549444" miny="11.307092" maxx="109.233267" maxy="12.166196"/>
<BoundingBox CRS="EPSG:4326" minx="11.307092" miny="108.549444" maxx="12.166196" maxy="109.233267"/>
<BoundingBox CRS="EPSG:0" minx="532687.840000" miny="1250489.700000" maxx="607009.080000" maxy="1345353.090000"/>
<BoundingBox CRS="EPSG:9217" minx="532687.840000" miny="1250489.700000" maxx="607009.080000" maxy="1345353.090000"/>
<Style>
<Name>default</Name>
<Title>1</Title>
<LegendURL width="166" height="144">
<Format>image/png</Format>
<OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://localhost:6080/arcgis/services/Test_BD/BDN/MapServer/WmsServer?request=GetLegendGraphic%26version=1.3.0%26format=image/png%26layer=1" xlink:type="simple"/>
</LegendURL>
</Style>
</Layer>
<Layer queryable="1">
<Name>2</Name>
<Title>
<![CDATA[ Địa giới NT ]]>
</Title>
<Abstract>
<![CDATA[ ]]>
</Abstract>
<CRS>CRS:84</CRS>
<CRS>EPSG:4326</CRS>
<CRS>EPSG:0</CRS>
<CRS>EPSG:9217</CRS>
<!--  9217 is customized SR = PROJCS["VN2000",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",108.25],PARAMETER["Scale_Factor",0.9999],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]  -->
<EX_GeographicBoundingBox>
<westBoundLongitude>108.549444</westBoundLongitude>
<eastBoundLongitude>109.233283</eastBoundLongitude>
<southBoundLatitude>11.307092</southBoundLatitude>
<northBoundLatitude>12.170651</northBoundLatitude>
</EX_GeographicBoundingBox>
<BoundingBox CRS="CRS:84" minx="108.549444" miny="11.307092" maxx="109.233283" maxy="12.170651"/>
<BoundingBox CRS="EPSG:4326" minx="11.307092" miny="108.549444" maxx="12.170651" maxy="109.233283"/>
<BoundingBox CRS="EPSG:0" minx="532687.840900" miny="1250489.697300" maxx="607009.080400" maxy="1345845.903300"/>
<BoundingBox CRS="EPSG:9217" minx="532687.840900" miny="1250489.697300" maxx="607009.080400" maxy="1345845.903300"/>
<Style>
<Name>default</Name>
<Title>2</Title>
<LegendURL width="124" height="96">
<Format>image/png</Format>
<OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://localhost:6080/arcgis/services/Test_BD/BDN/MapServer/WmsServer?request=GetLegendGraphic%26version=1.3.0%26format=image/png%26layer=2" xlink:type="simple"/>
</LegendURL>
</Style>
</Layer>
<Layer queryable="1">
<Name>3</Name>
<Title>
<![CDATA[ Trụ sở UBND các cấp ]]>
</Title>
<Abstract>
<![CDATA[ ]]>
</Abstract>
<CRS>CRS:84</CRS>
<CRS>EPSG:4326</CRS>
<CRS>EPSG:0</CRS>
<CRS>EPSG:9217</CRS>
<!--  9217 is customized SR = PROJCS["VN2000",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",108.25],PARAMETER["Scale_Factor",0.9999],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]  -->
<EX_GeographicBoundingBox>
<westBoundLongitude>108.690979</westBoundLongitude>
<eastBoundLongitude>109.170210</eastBoundLongitude>
<southBoundLatitude>11.338382</southBoundLatitude>
<northBoundLatitude>12.006145</northBoundLatitude>
</EX_GeographicBoundingBox>
<BoundingBox CRS="CRS:84" minx="108.690979" miny="11.338382" maxx="109.170210" maxy="12.006145"/>
<BoundingBox CRS="EPSG:4326" minx="11.338382" miny="108.690979" maxx="12.006145" maxy="109.170210"/>
<BoundingBox CRS="EPSG:0" minx="548133.108100" miny="1253928.935000" maxx="600205.405400" maxy="1327670.126000"/>
<BoundingBox CRS="EPSG:9217" minx="548133.108100" miny="1253928.935000" maxx="600205.405400" maxy="1327670.126000"/>
<Style>
<Name>default</Name>
<Title>3</Title>
<LegendURL width="136" height="80">
<Format>image/png</Format>
<OnlineResource xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="https://localhost:6080/arcgis/services/Test_BD/BDN/MapServer/WmsServer?request=GetLegendGraphic%26version=1.3.0%26format=image/png%26layer=3" xlink:type="simple"/>
</LegendURL>
</Style>
<MinScaleDenominator>9449.404762</MinScaleDenominator>
<MaxScaleDenominator>236235.119048</MaxScaleDenominator>
</Layer>
</Layer>
</Layer>
</Capability>
</WMS_Capabilities>

PROJ release version

According to https://proj.org/ , Could you plz declare which PROJ release version is used in this package.
I need PROJ 7.0.0 .

Initializing x0, y0 in stere.dart

When running:

double lat = 0;
double lon = 0;
var pointSrc = Point(x: lon, y: lat);
var projSrc = Projection('EPSG:4326');
var projDst = Projection('Stere') ??
Projection.add('Stere', '+proj=stere +lat_0=90 +lon_0=0 +lat_ts=0 +ellps=WGS84 +x_0=0 y_0=0',
);
// Forward transform (lonlat -> Stereographic)
var pointForward = projSrc.transform(projDst, pointSrc);

I got the following error in line 107 of stere.dart (where x0 is first used):

Unhandled exception:
NoSuchMethodError: The method '+' was called on null.
Receiver: null
Tried calling: +(0.0)

Problem is solved in stere.dart by changing:

StereographicSouthProjection.init(ProjParams params)
: lat0 = params.lat0,
long0 = params.long0,
lat_ts = params.lat_ts ?? double.nan, // fix js behavior
x0 = params.x0,
y0 = params.y0,

to:

StereographicSouthProjection.init(ProjParams params)
: lat0 = params.lat0,
long0 = params.long0,
lat_ts = params.lat_ts ?? double.nan, // fix js behavior
x0 = params.x0 ?? 0,
y0 = params.y0 ?? 0,

Adding support for nadgrids

Proj4js started to support nadgrids so it would be a nice feature to be implemented.

+proj=longlat not working on transformation

void transform() {
  final latOffset = 0.04086; // degrees
  final lonOffset = 0.36427; // degrees
  final source = Projection.get('WGS84');
  final target = Projection.parse(
      '+proj=longlat +lon_0=$lonOffset +lat_0=$latOffset +ellps=WGS84 +units=m +no_defs');
  final transform = ProjectionTuple(fromProj: source!, toProj: target);
  final transformed = transform.forward(Point(x: 7.421, y: 79.546));
  print('${transformed}');
}

I need to shift some coordinates to the correct location. I used the above code but it does not seems to transform the coordinates and only output the same coordinates that I give.

Migrate to null safety

@maRci002 Hi, do you have any plan to migrate? Will you accept PR if I do?

[question] get the epsg code from a projection

Hi, I have the case in which I am reading the prj wkt from a file that is a sidecar file of a tiff file.

In the case the projection is not registered, I would like to advise the user that a certain epsg code needs to be added as definition.

Is there a way to get the epsg code from a projection object?
This would help a lot to keep a list of registered projections and handle them.

Custom CRS give the wrong result on Proj4Dart.

Now I am using Proj4Dart V2.0.0 & Flutter 3.0.4, found some big different of transform coordinates from my custom CRS. This is my code:

`import 'package:proj4dart/proj4dart.dart';

void main() {
var n1 = 1657193.5292;
var e1 = 834934.4417;
var ptSrc = Point(x: e1, y: n1);
var projSrc =
Projection.parse('+proj=utm +zone=47 +datum=WGS84 +units=m +no_defs');
var projDst = Projection.parse(
'+proj=tmerc +lat_0=0.0 +lon_0=102.25 +k_0=1.0 +x_0=500000 +y_0=0 +a=6378297.0 +b=6356911.77779 +towgs84=0.0,0.0,0.0,0,0,0,0 +units=m +no_defs type=crs');
var tuple = ProjectionTuple(fromProj: projSrc, toProj: projDst);
var ptDst = tuple.forward(ptSrc);
print(
'FORWARD: Transform point ${ptSrc.toArray()} from EPSG:32647 to custom projection: ${ptDst.toArray()}');
}
`
The console printed:
FORWARD: Transform point [834934.4417, 1657193.5292] from EPSG:32647 to custom projection: [485333.96880976285, 1655549.4642448912]

The correct answer must be [485333.9690, 1655549.7316].
This is very strange due to I used pyproj version of Python that derived from PROJ4 also but gave the correct coordinates.
This is my Python code with the same Proj4 strings:
`from pyproj import CRS, Transformer

projsrc = CRS.from_proj4('+proj=utm +zone=47 +datum=WGS84 +units=m +no_defs')
projdst = CRS.from_proj4('+proj=tmerc +lat_0=0.0 +lon_0=102.25 +k_0=1.0 +x_0=500000 +y_0=0 +a=6378297.0 +b=6356911.77779 +towgs84=0.0,0.0,0.0,0,0,0,0 +units=m +no_defs type=crs');
xx, yy = 834934.4417, 1657193.5292
transformer = Transformer.from_crs(projsrc, projdst)
ptdst = transformer.transform(xx=xx, yy=yy)
print(f'Source point x,y: {xx} {yy}')
print(f'Dest point x,y: {ptdst[0]} {ptdst[1]}')`

The console of Python printed:
Source point x,y: 834934.4417 1657193.5292
Dest point x,y: 485333.9689740725 1655549.7315796772

I am new to Dart/Flutter what I am doing wrong or is it Proj4Dart's bug? Please help me. I run this code on Windows 11.

Is the ability to convert wgs84 coordinate system to tm128 coordinate system also supported?

Hello, I am trying to change the general latitude and longitude wgs84 coordinate system value to the TM128 coordinate system value.

I got the desired value by converting the wgs84 coordinate system to the Tm128 coordinate system in the proj4 package provided by node js.

const proj4 = require('proj4');
var from = 'WGS84'
var to = 'TM128'

proj4.defs('WGS84', "+proj=longlat +ellps=WGS84 +datum=WGS84 +no_defs");
proj4.defs('TM128', '+proj=tmerc +lat_0=38 +lon_0=128 +k=0.9999 +x_0=400000 +y_0=600000 +ellps=bessel +units=m +no_defs +towgs84=-115.80,474.99,674.11,1.16,-2.31,-1.63,6.43');
var xy = [126.947937,37.375219];
var result = proj4(from, to, xy); 

console.log(result)

But I need a conversion function in flutter. Can you guide me?

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