I am following Javi's tutorial on using non web Mercator tiles and successfully followed instructions and got it all working.

However, when I change to use my projection I would like to use I get the following error:Error: Invalid LatLng object: (NaN, NaN)

I have taken the Proj4 defintion from EPSG.io for British National Grid (EPSG:27700) and EPSG:27700 is declared in the PostGIS Spatial Ref Table.

I have tried a different projection, a random Australian one and that successfully worked, so am really confused why I am getting the error.

Can anyone help?


function main() {       
    var center = [51.479559, -0.241699]
    var map = new L.Map('map', {
      center: center,
      zoom: 4,
      crs: cartodb.proj('+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +towgs84=446.448,-125.157,542.06,0.15,0.247,0.842,-20.489 +units=m +no_defs', '27700')

    // add cartodb layer with one sublayer
    cartodb.createLayer(map, {
      user_name: 'tjmgis',
      type: 'cartodb',
      sublayers: [{
         sql: 'select cartodb_id, st_transform(the_geom, 27700) as the_geom_webmercator from world_borders',
         cartocss: '#layer { polygon-fill: #F00; polygon-opacity: 0.3; line-color: #F00; }'
  window.onload = main;

1 Answer 1


The problem is in this function of the extension:

function mapToWGS84(pt) {
    pt = projection.inverse(mercator.forward([pt.lng, pt.lat]));
    return new L.LatLng(pt[1], pt[0])

mercator.forward returns a point outside projections bounds and it fails. That happens when the map view bounds go outside projection bounds.

as a side note you may want to add this to the query:

st_transform(ST_Intersection(the_geom, ST_MakeEnvelope(-13, 0, 13, 90, 4326)), 27700)

in other to make sure there is no geometry outside range (the bounds I used are not correct)

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