パッケージ詳細v3.0.0

proj4dart

Proj4dart は、座標系間での点座標の変換を可能にする Dart ライブラリであり、基準面変換も含みます（proj4js/proj4js の Dart 版本）。

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Pub ポイント: 150

パッケージをインストール

flutter pub add proj4dart

パッケージ概要

公開情報に基づく選定ガイドです。参考としてご利用ください。

Proj4dart は、異なる空間参照系間での座標変換（datum シフトを含む）を可能にする Dart ライブラリです。proj4js の Dart 版として、堅牢な地理空間投影および変換機能を提供します。幅広い座標系をサポートしており、複数のプラットフォームで正確な地理データ操作が必要なアプリケーションに適しています。

用途

地理データの可視化
地図座標変換
GISアプリケーション開発
位置ベースのサービス統合
空間分析ツール
クロスプラットフォームマッピング

主な機能

複数の座標系をサポートしています
データ変換を含む
クロスプラットフォーム互換性
軽量で効率的
正確な投影計算
Dartネイティブ実装

適している対象

GISアプリを開発する開発者
地図付きのモバイルおよびウェブアプリ
座標の再投影が必要なアプリケーション
地理空間データを処理するバックエンドサービス

注意事項

座標系の理解が必要です
ポイント座標変換に限定
投影の正しく定義されていることに依存する
大規模なラスタ処理には適していません
組み込みマップレンダリングのサポートなし

元の README

関連するソースリポジトリの README 原文のスナップショットです。最新の内容はリポジトリをご覧ください。

PROJ4DART

Proj4dart is a Dart library to transform point coordinates from one coordinate system to another, including datum transformations (Dart version of proj4js/proj4js).

Installing

Add proj4dart to pubspec.yml (dependencies section), then run pub get to download the new dependencies.

dependencies:
  proj4dart: any # or the latest version on Pub

Using

Predefined Projection

There are 3 predefined Projections and 5 aliases by default:

EPSG:4326, which has the following alias:
- WGS84
EPSG:4269
EPSG:3857, which has the following aliases:
- EPSG:3785
- GOOGLE
- EPSG:900913
- EPSG:102113

If you wish to use one of the predefined ones use Named Projection which has the following signature:

  var projection = Projection.get('EPSG:4326')!;

User-defined Projection

Proj4dart supports Proj4 definition strings, OGC WKT definitions and ESRI WKT definitions. They can be obtained from epsg.io.

With Proj4 string definition

If you wish to define your own projection you can create it with a valid Proj4 string (here for EPSG:23700):

+proj=somerc +lat_0=47.14439372222222 +lon_0=19.04857177777778 +k_0=0.99993 +x_0=650000 +y_0=200000 +ellps=GRS67 +towgs84=52.17,-71.82,-14.9,0,0,0,0 +units=m +no_defs

The signature is:

var def = '+proj=somerc +lat_0=47.14439372222222 +lon_0=19.04857177777778 +k_0=0.99993 +x_0=650000 +y_0=200000 +ellps=GRS67 +towgs84=52.17,-71.82,-14.9,0,0,0,0 +units=m +no_defs';

// Named Projection signature, later find it from anywhere via Projection.get('EPSG:23700')
var namedProjection = Projection.add('EPSG:23700', def);
// Projection without name signature
var projection = Projection.parse(def);

For full example visit example/proj4dart_example.dart

With OGC WKT definition

If you wish to define your own projection you can create it with a valid OGC WKT string (here for EPSG:23700):

PROJCS["HD72 / EOV",GEOGCS["HD72",DATUM["Hungarian_Datum_1972",SPHEROID["GRS 1967",6378160,298.247167427,AUTHORITY["EPSG","7036"]],TOWGS84[52.17,-71.82,-14.9,0,0,0,0],AUTHORITY["EPSG","6237"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4237"]],PROJECTION["Hotine_Oblique_Mercator_Azimuth_Center"],PARAMETER["latitude_of_center",47.14439372222222],PARAMETER["longitude_of_center",19.04857177777778],PARAMETER["azimuth",90],PARAMETER["rectified_grid_angle",90],PARAMETER["scale_factor",0.99993],PARAMETER["false_easting",650000],PARAMETER["false_northing",200000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Y",EAST],AXIS["X",NORTH],AUTHORITY["EPSG","23700"]]

The signature is:

var def = 'PROJCS["HD72 / EOV",GEOGCS["HD72",DATUM["Hungarian_Datum_1972",SPHEROID["GRS 1967",6378160,298.247167427,AUTHORITY["EPSG","7036"]],TOWGS84[52.17,-71.82,-14.9,0,0,0,0],AUTHORITY["EPSG","6237"]],PRIMEM["Greenwich",0,AUTHORITY["EPSG","8901"]],UNIT["degree",0.0174532925199433,AUTHORITY["EPSG","9122"]],AUTHORITY["EPSG","4237"]],PROJECTION["Hotine_Oblique_Mercator_Azimuth_Center"],PARAMETER["latitude_of_center",47.14439372222222],PARAMETER["longitude_of_center",19.04857177777778],PARAMETER["azimuth",90],PARAMETER["rectified_grid_angle",90],PARAMETER["scale_factor",0.99993],PARAMETER["false_easting",650000],PARAMETER["false_northing",200000],UNIT["metre",1,AUTHORITY["EPSG","9001"]],AXIS["Y",EAST],AXIS["X",NORTH],AUTHORITY["EPSG","23700"]]';

// Named Projection signature, later find it from anywhere via Projection.get('EPSG:23700')
var namedProjection = Projection.add('EPSG:23700', def);
// Projection without name signature
var projection = Projection.parse(def);

For full example visit example/proj4dart_ogc_wkt_example.dart

With ESRI WKT definition

If you wish to define your own projection you can create it with a valid ESRI WKT string (here for EPSG:23700):

PROJCS["HD72_EOV",GEOGCS["GCS_HD72",DATUM["D_Hungarian_1972",SPHEROID["GRS_1967",6378160,298.247167427]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Hotine_Oblique_Mercator_Azimuth_Center"],PARAMETER["latitude_of_center",47.14439372222222],PARAMETER["longitude_of_center",19.04857177777778],PARAMETER["azimuth",90],PARAMETER["scale_factor",0.99993],PARAMETER["false_easting",650000],PARAMETER["false_northing",200000],UNIT["Meter",1]]

The signature is:

var def = 'PROJCS["HD72_EOV",GEOGCS["GCS_HD72",DATUM["D_Hungarian_1972",SPHEROID["GRS_1967",6378160,298.247167427]],PRIMEM["Greenwich",0],UNIT["Degree",0.017453292519943295]],PROJECTION["Hotine_Oblique_Mercator_Azimuth_Center"],PARAMETER["latitude_of_center",47.14439372222222],PARAMETER["longitude_of_center",19.04857177777778],PARAMETER["azimuth",90],PARAMETER["scale_factor",0.99993],PARAMETER["false_easting",650000],PARAMETER["false_northing",200000],UNIT["Meter",1]]');

// Named Projection signature, later find it from anywhere via Projection.get('EPSG:23700')
var namedProjection = Projection.add('EPSG:23700', def);
// Projection without name signature
var projection = Projection.parse(def);

For full example visit example/proj4dart_esri_wkt_example.dart

Grid Based Datum Adjustments

To use +nadgrids= in a proj definition, first read your NTv2 .gsb file into an Uint8List, then pass to Projection.nadgrid. E.g:

Dart:

final bytes = await File(
  'assets/my_grid.gsb',
).readAsBytes();

Projection.nadgrid('key', bytes);

Flutter:

import 'package:flutter/services.dart' show rootBundle;
final bytes = (await rootBundle.load(fileName)).buffer.asUint8List();

Projection.nadgrid('key', bytes);

then use the given key in your definition, e.g. +nadgrids=@key,null. See Proj4 General Parameters.

Nadgrid example:

import 'package:flutter/services.dart' show rootBundle;

final bytes = (await rootBundle.load('assets/nzgd2kgrid0005.gsb')).buffer.asUint8List();
Projection.nadgrid('nzgd2kgrid0005.gsb', bytes);

var def = '+proj=longlat +datum=nzgd49 +towgs84=59.47,-5.04,187.44,0.47,-0.1,1.024,-4.5993 +nadgrids=nzgd2kgrid0005.gsb +no_defs';
var namedProjection = Projection.add('EPSG:4272', def);

For full example visit example/proj4dart_shift_grid_example.dart

Transform between Projections

import 'package:proj4dart/proj4dart.dart';

void main() {
  // Define Point
  var pointSrc = Point(x: 17.888058560281515, y: 46.89226406700879);

  // Use built-in projection
  var projSrc = Projection.get('EPSG:4326')!;

  // Find Projection by name or define it if not exists
  var projDst = Projection.get('EPSG:23700') ??
      Projection.add(
        'EPSG:23700',
        '+proj=somerc +lat_0=47.14439372222222 +lon_0=19.04857177777778 +k_0=0.99993 +x_0=650000 +y_0=200000 +ellps=GRS67 +towgs84=52.17,-71.82,-14.9,0,0,0,0 +units=m +no_defs',
      );

  // Forward transform (lonlat -> projected crs)
  var pointForward = projSrc.transform(projDst, pointSrc);
  print(
      'FORWARD: Transform point ${pointSrc.toArray()} from EPSG:4326 to EPSG:23700: ${pointForward.toArray()}');
  // FORWARD: Transform point [17.888058560281515, 46.89226406700879] from EPSG:4326 to EPSG:23700: [561651.8408065987, 172658.61998377228]

  // Inverse transform (projected crs -> lonlat)
  var pointInverse = projDst.transform(projSrc, pointForward);
  print(
      'INVERSE: Transform point ${pointForward.toArray()} from EPSG:23700 to EPSG:4326: ${pointInverse.toArray()}');
  // INVERSE: Transform point [561651.8408065987, 172658.61998377228] from EPSG:23700 to EPSG:4326: [17.888058565574845, 46.89226406698969]
}

Transform between Projections using ProjectionTuple

import 'package:proj4dart/proj4dart.dart';

void main() {
  // Define Point
  var pointSrc = Point(x: 17.888058560281515, y: 46.89226406700879);

  // Define ProjectionTuple which makes vice versa conversions even easier
  var tuple = ProjectionTuple(
    // Use built-in projection
    fromProj: Projection.get('EPSG:4326')!,
    // Define custom projection
    toProj: Projection.parse(
      '+proj=somerc +lat_0=47.14439372222222 +lon_0=19.04857177777778 +k_0=0.99993 +x_0=650000 +y_0=200000 +ellps=GRS67 +towgs84=52.17,-71.82,-14.9,0,0,0,0 +units=m +no_defs',
    ),
  );

  // Forward transform (lonlat -> projected crs)
  var pointForward = tuple.forward(pointSrc);
  print(
      'FORWARD: Transform point ${pointSrc.toArray()} from EPSG:4326 to EPSG:23700: ${pointForward.toArray()}');
  // FORWARD: Transform point [17.888058560281515, 46.89226406700879] from EPSG:4326 to EPSG:23700: [561651.8408065987, 172658.61998377228]

  // Inverse transform (projected crs -> lonlat)
  var pointInverse = tuple.inverse(pointForward);
  print(
      'INVERSE: Transform point ${pointForward.toArray()} from EPSG:23700 to EPSG:4326: ${pointInverse.toArray()}');
  // INVERSE: Transform point [561651.8408065987, 172658.61998377228] from EPSG:23700 to EPSG:4326: [17.888058565574845, 46.89226406698969]
}

Accuracy

Proj4dart was tested with

8444 Proj4 definitions (test/data/all_proj4_defs.dart)
5642 OGC WKT definitions (test/data/all_proj4_ogc_wkt_defs.dart)
7426 ESRI WKT definitions (test/data/all_proj4_esri_wkt_defs.dart)

Forward and inverse transformations were both performed and checked in each case. The expected forward and inverse results were pre-calculated using proj4js (test/results/all_proj4_results.dart, test/results/all_proj4_ogc_wkt_results.dart, test/results/all_proj4_esri_wkt_results.dart).

The following table shows the avarage deltas of different Projections (using EPSG:4326 point of [17.888058560281515, 46.89226406700879] and transformed to Custom CRS defined with Proj4 definition string which gave the forward result then transformed back the received forward result which gave the inverse result):

Projection	No. tests	avg delta forward_x	avg delta forward_y	avg delta inverse_x	avg delta inverse_y
Albers Projection	58	2.8260822953849e-9	1.6378431484617036e-9	1.0719394720518753e-14	1.0903155772870503e-14
Azimuthal Equidistant Projection	12	7.761021455128987e-11	1.5522042910257974e-10	1.7763568394002505e-15	1.1842378929335002e-15
Cassini Projection	33	3.9510654680656665e-10	3.3866275440562856e-10	3.2297397080004555e-16	0.0
Central Cylindrical Projection	5	0.0	0.0	0.0	0.0
Equidistant Conic Projection	9	1.2935035758548312e-11	0.0	1.578983857244667e-15	0.0
Equidistant Cylindrical Projection	25	0.0	0.0	0.0	0.0
Geocentric Projection	196	0.0	0.0	9.06304509898087e-17	0.0
Gnomic Projection	2	0.0	0.0	3.552713678800501e-15	0.0
Hotine Oblique Mercator Projection	51	4.460304683330012e-9	8.017819959158991e-9	6.339155779820502e-15	3.901018941428001e-15
Krovak Projection	9	9.054525030983819e-10	1.448724004957411e-9	1.578983857244667e-15	3.157967714489334e-15
Lambert Azimuthal Equal-Area Projection	20	5.820766091346741e-11	0.0	5.329070518200751e-16	0.0
Lambert Conformal Conic Projection	2028	1.8960008225716005e-8	1.2588414830372427e-8	4.613097105712702e-14	8.064379757884726e-14
LongLat	1152	1.6961740653995446e-16	0.0	2.312964634635743e-16	2.7755575615628914e-16
Miller Cylindrical Projection	2	0.0	0.0	0.0	0.0
Mollweide Projection	2	0.0	0.0	0.0	0.0
New Zealand Map Grid Projection	1	0.0	0.0	0.000003294908452744494	0.000008533214440831216
Orthographic Projection	2	0.0	0.0	7.105427357601002e-15	3.552713678800501e-15
Polyconic Projection	10	0.0	0.0	1.1842378929335002e-15	0.0
Pseudo Mercator Projection	25	0.0	3.7252902984619143e-10	1.4210854715202004e-16	2.842170943040401e-16
Robinson Projection	2	0.0	0.0	0.0	0.0
Sinusoidal Projection	3	0.0	0.0	0.0	0.0
Stereographic North Projection	21	2.217434701465425e-11	2.993536846978324e-10	4.906128413581644e-15	1.3534147347811431e-15
Stereographic South Projection	44	2.43414258446509e-10	2.063731004268861e-10	1.3726393759001935e-15	0.0
Swiss Oblique Mercator Projection	5	4.656612873077393e-11	0.0	1.4210854715202005e-15	0.0
Transverse Mercator Projection	3445	7.527289676908484e-12	5.01819311793899e-12	3.966550829771659e-13	3.0942861377693824e-13
Universal Transverse Mercator Projection	1279	3.4847229055075836e-10	3.429655454604303e-10	3.4304936617033767e-15	2.4999548951684524e-15
Van der Grinten Projection	2	3.3760443329811096e-9	2.3283064365386963e-9	0.0	0.0

Example (using EPSG:4326 point of [17.888058560281515, 46.89226406700879] and transformed to EPSG:23700 defined with Proj4 definition string):

LIBRARY	forward_x	forward_y	inverse_x	inverse_y
proj4dart	561651.8408065987	172658.61998377228	17.888058565574845	46.89226406698969
proj4js	561651.8408065989	172658.61998377228	17.888058565574852	46.89226406698969
delta	0.0000000002	0.0	0.000000000000007	0.0

In some cases also manual PostGIS testing (PostgreSQL 12.1, PostGIS 3.0.0 r17983) was performed such as the following (using EPSG:4326 point of [17.888058560281515, 46.89226406700879] and transformed to EPSG:23700 defined with Proj4 definition string):

LIBRARY	forward_x	forward_y	inverse_x	inverse_y
proj4dart	561651.8408065987	172658.61998377228	17.888058565574845	46.89226406698969
PostGIS	561651.8408065987	172658.6199837724	17.88805856557482	46.8922640683514
delta	0.0	0.00000000012	0.000000000000025	0.00000000136171

Used by

Proj4dart is currently the default projection handler of flutter_map.

Authors

Proj4dart was ported from proj4js by @maRci002 and Gergely Padányi-Gulyás (@fegyi001).

カテゴリー

地理情報ユーティリティ

依存関係

依存関係一覧 3 件

meta^1.3.0
mgrs_dart^3.0.0
wkt_parser^2.0.0

ソースリポジトリ

maRci002/proj4dart

proj4dart

☆ 29 スター⑂ 3 フォーク

DartJavaScriptdartcrsproj4js

このパッケージを使用しているプロジェクト

deckerst/aves

パッケージをインストール

パッケージ概要

用途

主な機能

適している対象

注意事項

元の README

PROJ4DART

Installing

Using

Predefined Projection

User-defined Projection

With Proj4 string definition

With OGC WKT definition

With ESRI WKT definition

Grid Based Datum Adjustments

Transform between Projections

Transform between Projections using ProjectionTuple

Accuracy

Used by

Authors

カテゴリー

依存関係

ソースリポジトリ

proj4dart

このパッケージを使用しているプロジェクト

自由の鳥

ベルリン自転車盗難警告

at_client_sdk

flutter_map

宇宙