LeafletCRS projection issues

Question

I am trying to get a map in the Dutch Rijksdriehoekstelsel coordinates in a Leaflet map in R that is going in a Shiny app later. I am going to have to add polygons later, and changing their X and Y coordinates into the WGS84 would be horrible. I stole the proj4def and resolutions from the example posted at the bottom. However, I just get a grey screen with the zoom in and out buttons. Either I have screwed up the leafletOptions or the tileLayer.

library(leaflet)

leaflet(
 options =
    leafletOptions(
      crs=leafletCRS(
        crsClass="L.Proj.CRS.TMS",
        code='EPSG:28992',
        proj4def='+proj=sterea +lat_0=52.15616055555555 +lon_0=5.38763888888889 +k=0.9999079 +x_0=155000 +y_0=463000 +ellps=bessel +units=m +towgs84=565.2369,50.0087,465.658,-0.406857330322398,0.350732676542563,-1.8703473836068,4.0812 +no_defs',
  c(-285401.92, 22598.08, 595401.9199999999, 903401.9199999999),
    resolutions = c(3440.640, 1720.320, 860.160, 430.080, 215.040, 107.520, 53.760, 26.880, 13.440, 6.720, 3.360, 1.680, 0.840, 0.420),
      )
  )) %>%
  addTiles(urlTemplate='http://geodata.nationaalgeoregister.nl/tms/1.0.0/brtachtergrondkaart/{z}/{x}/{y}.png', 
  tileOptions(minZoom=3,maxZoom=13,tms=TRUE,continuousWorld=TRUE)   ) %>%
  setView(52,5.1,13)

This is an example in Javascript that has done the same thing: http://bl.ocks.org/webmappergists/raw/1ceac1353920b3810486/

Answer 1

First of all, the map is gray because you mixed up the coordinates. Just change the view from setView(52,5.1,13) to setView(5.1,52,13) and the map should render. It will be wrong though.

You had a few errors in your code. First you forgot to define the projectedBounds. You just added the vector without defining or doing anything whith it. It should look something like this:

projectedBounds = c(-285401.92, 22598.08, 595401.9199999999, 903401.9199999999))

So the entire crs should look like this:

minZoom = 0
maxZoom = 13
resolutions <- 0.42*(2^(maxZoom:minZoom))

epsg28992 <- leafletCRS(crsClass = 'L.Proj.CRS.TMS', code = 'EPSG:28992',
                       proj4def = '+proj=sterea +lat_0=52.15616055555555 +lon_0=5.38763888888889 +k=0.9999079 +x_0=155000 +y_0=463000 +ellps=bessel +towgs84=565.417,50.3319,465.552,-0.398957,0.343988,-1.8774,4.0725 +units=m +no_defs',
                       resolutions = resolutions,
                       projectedBounds = c(-285401.92, 22598.08, 595401.9199999999, 903401.9199999999))

Then you just have to add the tiles, set the view and you're done.

Entire code:

library(leaflet)

minZoom = 0
maxZoom = 13
resolutions <- 0.42*(2^(maxZoom:minZoom))

epsg28992 <- leafletCRS(crsClass = 'L.Proj.CRS.TMS', code = 'EPSG:28992',
                       proj4def = '+proj=sterea +lat_0=52.15616055555555 +lon_0=5.38763888888889 +k=0.9999079 +x_0=155000 +y_0=463000 +ellps=bessel +towgs84=565.417,50.3319,465.552,-0.398957,0.343988,-1.8774,4.0725 +units=m +no_defs',
                       resolutions = resolutions,
                       projectedBounds = c(-285401.92, 22598.08, 595401.9199999999, 903401.9199999999))

leaflet(options = leafletOptions(
                                  crs = epsg28992, 
                                  minZoom = minZoom, maxZoom = maxZoom)) %>%
  setView(5.092098, 52.093992, zoom = 4) %>%
  addTiles('http://geodata.nationaalgeoregister.nl/tms/1.0.0/brtachtergrondkaart/{z}/{x}/{y}.png', options = tileOptions(tms=TRUE))