Shapefile to TopoJSON conversion problems

问题

I'm trying to convert a shapefile to GeoJSON and then to TopoJSON as described in Let's Make a Map. Somewhere along the chain, something gets corrupted and my resulting image looks like below:

My workflow is as follows:

Download shapefile from: http://vcgi.vermont.gov/warehouse/search_tools - I am working with the Master Town Boundary data, specifically, the "Boundary_BNDHASH_region_towns.shp" file.

Convert shapefile to GeoJSON

ogr2ogr -f GeoJSON vt_towns.json Boundary_BNDHASH_region_towns.shp

Convert GeoJSON to TopoJSON

topojson -p TOWNNAME -p CNTY -o vt.json vt_towns.json

Plug into basic template with some minor modifications to Mike Bostock's example

<!DOCTYPE html>
<meta charset="utf-8">
<style>

/* CSS goes here. */

</style>
<body>
<script src="http://d3js.org/d3.v3.min.js"></script>
<script src="http://d3js.org/topojson.v1.min.js"></script>
<script>

    var width = 960,
        height = 1160;

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

    var projection = d3.geo.transverseMercator()
            .rotate([72.57, -44.20])
            .translate([175,185])
            .scale([100]);

    // Define path generator
    var path = d3.geo.path()
        .projection(projection);

    d3.json("vt.json", function(error, vt) {

        var vermont = topojson.feature(vt, vt.objects.vt_towns);

        svg.append("path")
            .datum(vermont)
            .attr("d", path);

    });

</script>

This is not my first d3 map (it's my second!) but I am very much at a loss as to what is going wrong. My best guess is that it has something to do with the unzipped dataset containing many shapefiles and their accompanying files.

回答1:

It seems that your file uses the gridded coordinate system, use the option -t_srs EPSG:4326 to get latitude and longitude:

ogr2ogr -f GeoJSON -t_srs EPSG:4326 vt_towns.json Boundary_BNDHASH_region_towns.shp

And then continue with your workflow.

来源：https://stackoverflow.com/questions/16925131/shapefile-to-topojson-conversion-problems

标签

d3.js

shapefile

geojson

topojson