I'm developing an app which should show a map using Leaflet framework but i have no luck as the coordinate system on the map server differs from the one used by Leaflet.
- As a map server i use Arcgis which is accessed by means of REST interface
The coordinate system used by the server is GCS_Bessel_1841. WKT definition:
GEOGCS["GCS_Bessel_1841",DATUM["D_Bessel_1841",SPHEROID["Bessel_1841",6377397.155,299.1528128]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",0.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",37.5],PARAMETER["Scale_Factor",1.0],PARAMETER["Latitude_Of_Origin",55.66666666666666],UNIT["Meter",1.0]
I use proj.4 to convert GCS_Bessel_1841 to WGS84 (used by leaflet) but can't figure out how to make a correct definition especially how to write +towgs84.
The question is how to figure out the values for DX,DY,DZ,RX,RY,RZ.
The afterall my proj.4 defitiion looks like: +proj=tmerc +lon_0=37.5 +lat_0=55.66666666666666 +ellps=bessel +towgs84=0,0,0,0,0,0,0 +a=6377397.155 +b=6356078.962818188 +pm=greenwich +k_0=1 +x_0=0 +y_0=0 +units=m +no_defs
The Leaflet code:
`var crs = new L.Proj.CRS('EPSG:3857', '+proj=tmerc +lat_0=55.66666666666666 +lon_0=37.5 +k=1 +x_0=0 +y_0=0 +ellps=bessel +units=m +no_defs', { origin: [-5622500.0, 3830200.0], resolutions: [ 305.74811314055756, 152.87405657041106, 76.43702828507324, 38.21851414253662, 19.10925707126831, 9.554628535634155, 4.77731426794937, 2.388657133974685, 1.1943285668550503, 0.5971642835598172, 0.29858214164761665, 0.14929107082380833 ] });
var map = new L.Map('map', { crs: crs });
var tileUrl = 'http://egip.mka.mos.ru/arcgis/rest/services/osnova_wgs_cached/MapServer/tile/{z}/{y}/{x}', attrib = '© 2012', tilelayer = new L.TileLayer(tileUrl, { maxZoom: 12, minZoom: 0, continuousWorld: true, attribution: attrib, });
map.addLayer(tilelayer); map.setView([ 55.750984, 37.617571], 0);
map.on('mousemove', onMapMouseMove);' `
gdalsrsinfo Moscow_bessel.prj
PROJ.4 : '+proj=tmerc +lat_0=0 +lon_0=0 +k=1 +x_0=0 +y_0=0 +ellps=bessel +to_meter=0 +no_defs '
PROJ.4 : '+proj=tmerc +lat_0=55.66666666666666 +lon_0=37.5 +k=1 +x_0=0 +y_0=0 +ellps=bessel +units=m +no_defs '