3

UPDATE: Solved, sort of … I downloaded the file afresh and tried feeding it through ogr2ogr and topojson again … and wouldn't you know … after a while it worked. I think I was possibly not setting an id property. This was a big help: https://stackoverflow.com/questions/14565963/topojson-for-congressional-districts

ORIGINAL POST: So, for the friends who have used Tiger shapefiles, clue me in on my mistake here?

I suspect it's something with wrong projection or wrong conversion from shapefiles? The .xml suggests the projection is WGS_1984_Web_Mercator_Auxiliary_Sphere

I converted with ogr2ogr then to topojson, a la the Mike Bostock canonical example: http://bost.ocks.org/mike/map/ (FWIW, I also tried with mapshaper.org and also got a bunch of shards.)

UPDATE: I wasn't clear abt mapshaper.org -- it displays this file perfectly online, but when I download topo from it, yea, I get shards.

This should be a map of two Georgia counties, an area maybe 100 miles across. The shapefile came from U.S. Census Tiger.

I got another shapefile of the same area from our state mapping agency and it mapped perfectly.

Any ideas?

UPDATE: here is the shapefile I've been using: https://www.dropbox.com/s/kux63jdo66h87uk/reference_map_shape.zip?dl=0

d3.json("050_002.json", function(error, counties) {
  if (error) return console.error(error);
  console.log("ok counties:", counties)


  var projection = d3.geo.mercator()
    .scale(100)
    .rotate([84.2, -33.9, 0]);


var path = d3.geo.path()
  .projection(projection);

svg.append("path")
  .datum(topojson.feature(counties, counties.objects['050_00']))
  .attr("d", path)

enter image description here

  • Can you post the Tiger shape file you have been working with? – cengel Oct 1 '14 at 22:01
3

Reproject from Web Mercator, for example to WGS84

ogr2ogr -f GeoJson 050_00wgs84.gjson 050_00.shp -s_srs EPSG:3857 -t_srs EPSG:4326
topojson --id-property=GEO_ID -o 050_00wgs84.json -- 050_00wgs84.gjson

Then:

var width = 800,
height = 800;

var svg = d3.select("body").append("svg")
 .attr("width", width)
 .attr("height", height);

d3.json("050_00wgs84.json", function(error, counties) {

  var projection = d3.geo.mercator()
    .center([-84.5, 34])
    .scale(40000);

  var path = d3.geo.path()
    .projection(projection);

  svg.append("path")
    .datum(topojson.feature(counties, counties.objects['050_00wgs84']))
    .attr("d", path)
    .attr("fill",'#999');  
});

enter image description here

| improve this answer | |
  • I wish I had enough points to upvote you! Thanks! – Maggie Oct 2 '14 at 18:18
  • 1
    @Maggie, great to hear this was helpful. I just upvoted your question, you should have enough points now. Could you also accept this as answer? – cengel Oct 3 '14 at 16:08

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