Projection setting d3.geoPath () does not work as documented
I've done a lot of maps in D3 and never had this problem where the output is so small you can't see it. I have included a small geojson file that can be easily viewed with other tools ( for example, here ).
It looks like the projection is not set properly with d3.geoPath (). The API indicates that d3.geoPath () takes a projection argument, however when I try to adjust the projection using this method (as in the example below) the resulting map is not projected correctly. This is only after I set the projection using the d3.geoPath () method. Projection () to get the correct result.
Is this a bug in the documentation or am I missing something?
//setup and map parameters
var height = 300;
var width = 300;
var projection = d3.geoAlbers().scale(1000).translate([width/2, height/2]);
var path = d3.geoPath(projection);
//geoJSON data
var geojson =
{"type":"FeatureCollection","features":[
{"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[-86.910592,33.536105],[-86.907192,33.542204999999996],[-86.90539199999999,33.541305],[-86.901608,33.543456],[-86.895692,33.548805],[-86.89249199999999,33.550404],[-86.888392,33.549304],[-86.879772,33.553267999999996],[-86.868549,33.553418],[-86.8651,33.557134999999995],[-86.856129,33.562064],[-86.85159499999999,33.559404],[-86.848891,33.559805],[-86.852991,33.552104],[-86.85519099999999,33.543904999999995],[-86.855694,33.538151],[-86.860817,33.53405],[-86.850509,33.535693],[-86.83124699999999,33.544767],[-86.827029,33.534708],[-86.82383999999999,33.533389],[-86.826703,33.528081],[-86.826807,33.521107],[-86.822808,33.514319],[-86.81474899999999,33.502386],[-86.81411899999999,33.500078],[-86.816041,33.496234],[-86.823825,33.488839],[-86.825743,33.485408],[-86.82772299999999,33.477393],[-86.828558,33.472626999999996],[-86.82791,33.46967],[-86.833503,33.467552999999995],[-86.839366,33.463845],[-86.841534,33.460941],[-86.842309,33.465699],[-86.849758,33.466302],[-86.861663,33.456759],[-86.869367,33.4514],[-86.87749699999999,33.449382],[-86.884293,33.445453],[-86.88948599999999,33.441072999999996],[-86.890131,33.438437],[-86.899491,33.434508],[-86.908391,33.429308],[-86.922929,33.415512],[-86.925484,33.419897999999996],[-86.93114299999999,33.422801],[-86.93749199999999,33.421608],[-86.945352,33.425982999999995],[-86.946468,33.428407],[-86.937809,33.435314],[-86.925764,33.449968999999996],[-86.920859,33.454651999999996],[-86.92215,33.456643],[-86.927679,33.453849999999996],[-86.932965,33.449332],[-86.935435,33.446132],[-86.94133699999999,33.442150999999996],[-86.941301,33.445651999999995],[-86.942842,33.450103],[-86.946817,33.45017],[-86.95131599999999,33.45181],[-86.950279,33.458104],[-86.945494,33.463234],[-86.929693,33.478538],[-86.92935299999999,33.479858],[-86.920255,33.492874],[-86.92450699999999,33.493904],[-86.93110999999999,33.496843],[-86.933543,33.494935999999996],[-86.94144999999999,33.494743],[-86.944717,33.495934],[-86.946237,33.502279],[-86.946224,33.506071],[-86.941811,33.507621],[-86.937693,33.512206],[-86.92634,33.512381999999995],[-86.917255,33.517139],[-86.915435,33.519832],[-86.908779,33.518958999999995],[-86.903385,33.516537],[-86.898659,33.520165999999996],[-86.894459,33.526136],[-86.896992,33.530504],[-86.910592,33.536105]]]},"properties":{"a":1}}
]}
var svg = d3.select("#map");
svg.selectAll("path").data(geojson.features).enter().append("path").attr("fill","red").attr("d", path);
<script src="https://d3js.org/d3.v4.min.js"></script>
<svg height="300px" width="300px" id="map"> </svg>
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You will need to adjust the projection parameters correctly. A scale factor of 1,000 is small to show a small area like in your example. A scale factor of 50,000 may be more appropriate. You must also center your map correctly.
You will need to find a point near the center of your function in order to center the map correctly. You can do it manually using Google Earth or other methods to find the centroid of the path in geographic coordinates (not svg coordinates, however you can find svg centroid to refine the projection and also by translating the functions, I don't use this approach in my answer , though).
With the Albers projection, you have to lean on the y-axis and rotate along the x-axis:
var projection = d3.geoAlbers()
.rotate([-x,0])
.center([0,y])
.scale(k)
.translate([width/2,height/2])
You want to use the negative of your central meridian because you are rotating the globe under the map. See this answer for a more detailed description of the Albers options
The Albers projection at d3 has a default center and coordinate rotation. If you do not set the center coordinates for both pivot and center, the map will retain the default settings, which are intended to display the entire US; this will change the intended projection. Other projections tend to focus on [0,0] in the default d3, which is off the coast of Africa.
I looked at the coordinates of the center using Google Earth for use in this projection. The centering point I'm using here is:
86.884 degrees West (-86.884 degrees East)
33.507 degress North
I also zoomed in a lot more than your original scaling factor, using 100,000 rather than 1,000. Here's a prediction showing your data:
//setup and map parameters
var height = 300;
var width = 300;
var projection = d3.geoAlbers()
.scale(100000)
.translate([width/2, height/2])
.rotate([86.884,0])
.center([0,33.507]);
var path = d3.geoPath(projection);
//geoJSON data
var geojson =
{"type":"FeatureCollection","features":[
{"type":"Feature","geometry":{"type":"Polygon","coordinates":[[[-86.910592,33.536105],[-86.907192,33.542204999999996],[-86.90539199999999,33.541305],[-86.901608,33.543456],[-86.895692,33.548805],[-86.89249199999999,33.550404],[-86.888392,33.549304],[-86.879772,33.553267999999996],[-86.868549,33.553418],[-86.8651,33.557134999999995],[-86.856129,33.562064],[-86.85159499999999,33.559404],[-86.848891,33.559805],[-86.852991,33.552104],[-86.85519099999999,33.543904999999995],[-86.855694,33.538151],[-86.860817,33.53405],[-86.850509,33.535693],[-86.83124699999999,33.544767],[-86.827029,33.534708],[-86.82383999999999,33.533389],[-86.826703,33.528081],[-86.826807,33.521107],[-86.822808,33.514319],[-86.81474899999999,33.502386],[-86.81411899999999,33.500078],[-86.816041,33.496234],[-86.823825,33.488839],[-86.825743,33.485408],[-86.82772299999999,33.477393],[-86.828558,33.472626999999996],[-86.82791,33.46967],[-86.833503,33.467552999999995],[-86.839366,33.463845],[-86.841534,33.460941],[-86.842309,33.465699],[-86.849758,33.466302],[-86.861663,33.456759],[-86.869367,33.4514],[-86.87749699999999,33.449382],[-86.884293,33.445453],[-86.88948599999999,33.441072999999996],[-86.890131,33.438437],[-86.899491,33.434508],[-86.908391,33.429308],[-86.922929,33.415512],[-86.925484,33.419897999999996],[-86.93114299999999,33.422801],[-86.93749199999999,33.421608],[-86.945352,33.425982999999995],[-86.946468,33.428407],[-86.937809,33.435314],[-86.925764,33.449968999999996],[-86.920859,33.454651999999996],[-86.92215,33.456643],[-86.927679,33.453849999999996],[-86.932965,33.449332],[-86.935435,33.446132],[-86.94133699999999,33.442150999999996],[-86.941301,33.445651999999995],[-86.942842,33.450103],[-86.946817,33.45017],[-86.95131599999999,33.45181],[-86.950279,33.458104],[-86.945494,33.463234],[-86.929693,33.478538],[-86.92935299999999,33.479858],[-86.920255,33.492874],[-86.92450699999999,33.493904],[-86.93110999999999,33.496843],[-86.933543,33.494935999999996],[-86.94144999999999,33.494743],[-86.944717,33.495934],[-86.946237,33.502279],[-86.946224,33.506071],[-86.941811,33.507621],[-86.937693,33.512206],[-86.92634,33.512381999999995],[-86.917255,33.517139],[-86.915435,33.519832],[-86.908779,33.518958999999995],[-86.903385,33.516537],[-86.898659,33.520165999999996],[-86.894459,33.526136],[-86.896992,33.530504],[-86.910592,33.536105]]]},"properties":{"a":1}}
]}
var svg = d3.select("#map");
svg.selectAll("path").data(geojson.features).enter().append("path").attr("fill","red").attr("d", path);
<script src="https://d3js.org/d3.v4.min.js"></script>
<svg height="300px" width="300px" id="map"> </svg>
source to share