duhaime/.block

## .block
license: mit

## README.md

      
    Raw
  

              README.md
            
          
    Ported to d3v4 by Philippe Rivière from Ian Johnson's block: visualizing map distortion

@enjalot: Whenever we try to represent our 3D earth on a 2D map we necessarily introduce distortion. This tool attempts to visualize the phenomenon.
Inspiration

Original prompt by @curran

Bounding box solution by @tyrasd
References

projection comparison

map zoom

  
## index.html
<!DOCTYPE html>
<head>
  <meta charset="utf-8">
<script src="//d3js.org/d3.v4.min.js"></script>
<script src="//d3js.org/d3-geo-projection.v2.min.js"></script>
<script src="//d3js.org/topojson.v1.min.js"></script>
<style>
  svg {
    margin: 22px;
  }
  select {
    margin-left: 20px;
  }
  path.foreground {
    fill: none;
    stroke: #333;
    stroke-width: 1.5px;
  }
  path.graticule {
    fill: none;
    stroke: #aaa;
    stroke-width: .5px;
  }
  #left {
    cursor: move;
  }
  #left .land {
    fill: #d7c7ad;
    stroke: #a5967e;
  }
  #right .land {
    fill: #cfcece;
    stroke: #a5967e;
  }

  #left circle {
    fill: #d8355e;
  }
  #right circle {
    stroke: #d8355e;
    fill: none;
  }
</style>
</head>

<body>
  <svg id="left"></svg>
  <svg id="right"></svg>
  <select></select>

  <script>

    var map_width = 400;
    var map_height = 400;
    var center = [-90, 37];
    var scale0 = (map_width - 1) / 2 / Math.PI * 6
    var scale1 = (map_width - 1) / 2 / Math.PI * 3

    var zoom = d3.zoom()
    .on("zoom", zoomed);


    var projectionLeft = d3.geoAitoff()
    .center(center)

    var projectionRight = d3.geoOrthographic()
    .center(center)
    .translate([map_width/5, map_height / 5])
    .scale(scale1)
    .clipAngle(90)

    var pathLeft = d3.geoPath()
        .projection(projectionLeft);
    var pathRight = d3.geoPath()
        .projection(projectionRight);

    function zoomed() {
      projectionLeft
          .translate([d3.event.transform.x, d3.event.transform.y])
          .scale(d3.event.transform.k)

      var newCenter = projectionLeft.invert([map_width/2,map_height/2]);
      projectionRight .rotate([-newCenter[0], -newCenter[1]])

      update();
    }

    function update() {
      d3.selectAll("#left path")
          .attr("d", pathLeft);
      d3.selectAll("#right path")
          .attr("d", pathRight);

      d3.selectAll("#left circle")
      .attr('transform', function(d,i) {
        return 'translate(' + [ d.x, d.y ] + ')';
      })

      d3.selectAll("#right circle")
      .attr('transform', function(d,i) {
        try {
          var latlon = projectionLeft.invert([d.x, d.y])
          return 'translate(' + projectionRight(latlon) + ')';
        } catch(e) {
          return 'translate(-100,-100)';
        }
      })
    }


    var graticule = d3.geoGraticule();
    var svgLeft = d3.select("#left")
        .attr("width", map_width)
        .attr("height", map_height);
    var svgRight = d3.select("#right")
        .attr("width", map_width + 40)
        .attr("height", map_height);

    svgLeft.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", pathLeft);

    svgRight.append("path")
        .datum(graticule)
        .attr("class", "graticule")
        .attr("d", pathRight);

    d3.json("world-110m.json", function(error,world) {
      if (error) throw error;

      svgLeft.insert("path", ".graticule")
          .datum(topojson.feature(world, world.objects.land))
          .attr("class", "land")
          .attr("d", pathLeft);

      svgRight.insert("path", ".graticule")
          .datum(topojson.feature(world, world.objects.land))
          .attr("class", "land")
          .attr("d", pathRight);

      var points = generateRect(100, 25, 25, map_width - 50, map_height - 50);

      svgLeft.selectAll("circle")
        .data(points)
        .enter().append("circle")
        .attr('r', 3)

      svgRight.selectAll("circle")
        .data(points)
        .enter().append("circle")
        .attr('r', 2)

      svgLeft
        .call(zoom)
        .call(
          zoom.transform,
           d3.zoomIdentity.translate(map_width/2,map_height/2)
           .scale(scale0)
        )
      ;
    });

    var projections = {
      "Aitoff": d3.geoAitoff().scale(90),
      "Boggs Eumorphic": d3.geoBoggs().scale(90),
      "Craster Parabolic (Putnins P4)": d3.geoCraster().scale(90),
      "Cylindrical Equal-Area": d3.geoCylindricalEqualArea().scale(120),
      "Eckert I": d3.geoEckert1().scale(95),
      "Eckert III": d3.geoEckert3().scale(105),
      "Eckert IV": d3.geoEckert4().scale(105),
      "Eckert V": d3.geoEckert5().scale(100),
      "Equidistant Cylindrical (Plate Carrée)": d3.geoEquirectangular().scale(90),
      "Fahey": d3.geoFahey().scale(75),
      "Foucaut Sinusoidal": d3.geoFoucaut().scale(80),
      "Gall (Gall Stereographic)": d3.geoCylindricalStereographic().scale(70),
      "Ginzburg VIII (TsNIIGAiK 1944)": d3.geoGinzburg8().scale(75),
      "Kavraisky VII": d3.geoKavrayskiy7().scale(90),
      "Larrivée": d3.geoLarrivee().scale(55),
      "McBryde-Thomas Flat-Pole Sine (No. 2)": d3.geoMtFlatPolarSinusoidal().scale(95),
      "Mercator": d3.geoMercator().scale(50),
      "Miller Cylindrical I": d3.geoMiller().scale(60),
      "Mollweide": d3.geoMollweide().scale(100),
      "Natural Earth": d3.geoNaturalEarth().scale(100),
      "Nell-Hammer": d3.geoNellHammer().scale(120),
      "Quartic Authalic": d3.geoHammer().coefficient(Infinity).scale(95),
      "Robinson": d3.geoRobinson().scale(90),
      "Sinusoidal": d3.geoSinusoidal().scale(90),
      "van der Grinten (I)": d3.geoVanDerGrinten().scale(50),
      "Wagner VI": d3.geoWagner6().scale(90),
      "Wagner VII": d3.geoWagner7().scale(90),
      "Winkel Tripel": d3.geoWinkel3().scale(90),
      "Wiechel": d3.geoWiechel().scale(90)    };
    var selector = d3.select("select")
    selector.selectAll("option")
      .data(Object.keys(projections))
      .enter().append("option")
      .attr('value', function(d) { return d }).text(function(d) { return d })

    selector.on("change", function(d) {
      console.log("sup", d3.event)
      var proj = d3.event.target.selectedOptions[0].value;
      projectionLeft = projections[proj].center(center);
      pathLeft = d3.geoPath()
        .projection(projectionLeft);
      svgLeft
        .call(zoom)
        .call(
          zoom.transform,
           d3.zoomIdentity.translate(map_width/2,map_height/2)
           .scale(scale0)
        )
      ;
    })


    function generateRect(num, x, y, width, height) {
      var points = []
      var sideNum = Math.floor(num/4) + 1;
      // top
      d3.range(sideNum).forEach(function(i) {
        points.push({ x: x + i * width/sideNum, y: y })
      })
      // right
      d3.range(sideNum).forEach(function(i) {
        points.push({ x: x + width, y: y + i * height/sideNum })
      })
      // bottom
      d3.range(sideNum).forEach(function(i) {
        points.push({ x: x + width - i * width/sideNum, y: y + height })
      })
      // left
      d3.range(sideNum).forEach(function(i) {
        points.push({ x: x, y: y + height - i * height/sideNum })
      })
      return points;
    }

  </script>
</body>


<script>
  (function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
  (i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
  m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
  })(window,document,'script','//www.google-analytics.com/analytics.js','ga');
  ga('create', 'UA-67666917-1', 'auto');
  ga('send', 'pageview');
</script>

## thumbnail.png

      
    Raw
  

              thumbnail.png
            
          
## world-110m.json

      
Display the source blob

    
Display the rendered blob

    
    Raw
  

              world-110m.json
            
          
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          Viewer requires iframe.
	<!DOCTYPE html>
	<head>
	<meta charset="utf-8">
	<script src="//d3js.org/d3.v4.min.js"></script>
	<script src="//d3js.org/d3-geo-projection.v2.min.js"></script>
	<script src="//d3js.org/topojson.v1.min.js"></script>
	<style>
	svg {
	margin: 22px;
	}
	select {
	margin-left: 20px;
	}
	path.foreground {
	fill: none;
	stroke: #333;
	stroke-width: 1.5px;
	}
	path.graticule {
	fill: none;
	stroke: #aaa;
	stroke-width: .5px;
	}
	#left {
	cursor: move;
	}
	#left .land {
	fill: #d7c7ad;
	stroke: #a5967e;
	}
	#right .land {
	fill: #cfcece;
	stroke: #a5967e;
	}

	#left circle {
	fill: #d8355e;
	}
	#right circle {
	stroke: #d8355e;
	fill: none;
	}
	</style>
	</head>

	<body>
	<svg id="left"></svg>
	<svg id="right"></svg>
	<select></select>

	<script>

	var map_width = 400;
	var map_height = 400;
	var center = [-90, 37];
	var scale0 = (map_width - 1) / 2 / Math.PI * 6
	var scale1 = (map_width - 1) / 2 / Math.PI * 3

	var zoom = d3.zoom()
	.on("zoom", zoomed);


	var projectionLeft = d3.geoAitoff()
	.center(center)

	var projectionRight = d3.geoOrthographic()
	.center(center)
	.translate([map_width/5, map_height / 5])
	.scale(scale1)
	.clipAngle(90)

	var pathLeft = d3.geoPath()
	.projection(projectionLeft);
	var pathRight = d3.geoPath()
	.projection(projectionRight);

	function zoomed() {
	projectionLeft
	.translate([d3.event.transform.x, d3.event.transform.y])
	.scale(d3.event.transform.k)

	var newCenter = projectionLeft.invert([map_width/2,map_height/2]);
	projectionRight .rotate([-newCenter[0], -newCenter[1]])

	update();
	}

	function update() {
	d3.selectAll("#left path")
	.attr("d", pathLeft);
	d3.selectAll("#right path")
	.attr("d", pathRight);

	d3.selectAll("#left circle")
	.attr('transform', function(d,i) {
	return 'translate(' + [ d.x, d.y ] + ')';
	})

	d3.selectAll("#right circle")
	.attr('transform', function(d,i) {
	try {
	var latlon = projectionLeft.invert([d.x, d.y])
	return 'translate(' + projectionRight(latlon) + ')';
	} catch(e) {
	return 'translate(-100,-100)';
	}
	})
	}



	var graticule = d3.geoGraticule();
	var svgLeft = d3.select("#left")
	.attr("width", map_width)
	.attr("height", map_height);
	var svgRight = d3.select("#right")
	.attr("width", map_width + 40)
	.attr("height", map_height);

	svgLeft.append("path")
	.datum(graticule)
	.attr("class", "graticule")
	.attr("d", pathLeft);

	svgRight.append("path")
	.datum(graticule)
	.attr("class", "graticule")
	.attr("d", pathRight);

	d3.json("world-110m.json", function(error,world) {
	if (error) throw error;

	svgLeft.insert("path", ".graticule")
	.datum(topojson.feature(world, world.objects.land))
	.attr("class", "land")
	.attr("d", pathLeft);

	svgRight.insert("path", ".graticule")
	.datum(topojson.feature(world, world.objects.land))
	.attr("class", "land")
	.attr("d", pathRight);

	var points = generateRect(100, 25, 25, map_width - 50, map_height - 50);

	svgLeft.selectAll("circle")
	.data(points)
	.enter().append("circle")
	.attr('r', 3)

	svgRight.selectAll("circle")
	.data(points)
	.enter().append("circle")
	.attr('r', 2)

	svgLeft
	.call(zoom)
	.call(
	zoom.transform,
	d3.zoomIdentity.translate(map_width/2,map_height/2)
	.scale(scale0)
	)
	;
	});

	var projections = {
	"Aitoff": d3.geoAitoff().scale(90),
	"Boggs Eumorphic": d3.geoBoggs().scale(90),
	"Craster Parabolic (Putnins P4)": d3.geoCraster().scale(90),
	"Cylindrical Equal-Area": d3.geoCylindricalEqualArea().scale(120),
	"Eckert I": d3.geoEckert1().scale(95),
	"Eckert III": d3.geoEckert3().scale(105),
	"Eckert IV": d3.geoEckert4().scale(105),
	"Eckert V": d3.geoEckert5().scale(100),
	"Equidistant Cylindrical (Plate Carrée)": d3.geoEquirectangular().scale(90),
	"Fahey": d3.geoFahey().scale(75),
	"Foucaut Sinusoidal": d3.geoFoucaut().scale(80),
	"Gall (Gall Stereographic)": d3.geoCylindricalStereographic().scale(70),
	"Ginzburg VIII (TsNIIGAiK 1944)": d3.geoGinzburg8().scale(75),
	"Kavraisky VII": d3.geoKavrayskiy7().scale(90),
	"Larrivée": d3.geoLarrivee().scale(55),
	"McBryde-Thomas Flat-Pole Sine (No. 2)": d3.geoMtFlatPolarSinusoidal().scale(95),
	"Mercator": d3.geoMercator().scale(50),
	"Miller Cylindrical I": d3.geoMiller().scale(60),
	"Mollweide": d3.geoMollweide().scale(100),
	"Natural Earth": d3.geoNaturalEarth().scale(100),
	"Nell-Hammer": d3.geoNellHammer().scale(120),
	"Quartic Authalic": d3.geoHammer().coefficient(Infinity).scale(95),
	"Robinson": d3.geoRobinson().scale(90),
	"Sinusoidal": d3.geoSinusoidal().scale(90),
	"van der Grinten (I)": d3.geoVanDerGrinten().scale(50),
	"Wagner VI": d3.geoWagner6().scale(90),
	"Wagner VII": d3.geoWagner7().scale(90),
	"Winkel Tripel": d3.geoWinkel3().scale(90),
	"Wiechel": d3.geoWiechel().scale(90) };
	var selector = d3.select("select")
	selector.selectAll("option")
	.data(Object.keys(projections))
	.enter().append("option")
	.attr('value', function(d) { return d }).text(function(d) { return d })

	selector.on("change", function(d) {
	console.log("sup", d3.event)
	var proj = d3.event.target.selectedOptions[0].value;
	projectionLeft = projections[proj].center(center);
	pathLeft = d3.geoPath()
	.projection(projectionLeft);
	svgLeft
	.call(zoom)
	.call(
	zoom.transform,
	d3.zoomIdentity.translate(map_width/2,map_height/2)
	.scale(scale0)
	)
	;
	})


	function generateRect(num, x, y, width, height) {
	var points = []
	var sideNum = Math.floor(num/4) + 1;
	// top
	d3.range(sideNum).forEach(function(i) {
	points.push({ x: x + i * width/sideNum, y: y })
	})
	// right
	d3.range(sideNum).forEach(function(i) {
	points.push({ x: x + width, y: y + i * height/sideNum })
	})
	// bottom
	d3.range(sideNum).forEach(function(i) {
	points.push({ x: x + width - i * width/sideNum, y: y + height })
	})
	// left
	d3.range(sideNum).forEach(function(i) {
	points.push({ x: x, y: y + height - i * height/sideNum })
	})
	return points;
	}

	</script>
	</body>


	<script>
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	(i[r].q=i[r].q\|\|[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
	m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
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