2f:T461,function invert(d) { console.log( 'inverting.............' ); console.log(d) const shared = {}; let p = { type: "Polygon", coordinates: d3.merge(d.coordinates.map(polygon => { return polygon.map(ring => { return ring.map(point => { return [point[0] / n * 360 - 180, 90 - point[1] / m * 180]; }).reverse(); }); })) }; // Record the y-intersections with the antimeridian. p.coordinates.forEach(ring => { ring.forEach(p => { if (p[0] === -180) shared[p[1]] |= 1; else if (p[0] === 180) shared[p[1]] |= 2; }); }); // Offset any unshared antimeridian points to prevent their stitching. p.coordinates.forEach(ring => { ring.forEach(p => { if ((p[0] === -180 || p[0] === 180) && shared[p[1]] !== 3) { p[0] = p[0] === -180 ? -179.9995 : 179.9995; } }); }); p = d3.geoStitch(p); p.value = d.value; // If the MultiPolygon is empty, treat it as the Sphere. return p.coordinates.length ? {type: "Polygon", coordinates: p.coordinates, value: d.value} : {type: "Sphere", value: d.value}; }30:T49a,function map() { var canvas = this || DOM.canvas(width,500), context = canvas.getContext("2d"), path = d3.geoPath().projection(projection.fitExtent([[1, 1], [width-1, 500-1]], {type: "Sphere"})).context(context); const render = function() { context.clearRect(0,0,width,500); polygons.forEach((p,i) => { context.beginPath(), path(p), context.fillStyle = color( p.value ), context.fill(), context.strokeStyle = 'black', context.lineWidth = 0.2, context.stroke(); }); context.beginPath(), path(d3.geoGraticule()()), context.lineWidth = 0.2, context.strokeStyle = 'black', context.stroke(); context.beginPath(), path(land), context.lineWidth = 0.5, context.strokeStyle = 'black', context.stroke() context.beginPath(), path({type: "Sphere"}), context.lineWidth = 1.5, context.strokeStyle = 'rgba(0,0,0,.5)', context.stroke(); } if (d3.geoInertiaDrag) d3.geoInertiaDrag(d3.select(canvas).style('cursor', 'move'), null, projection) var timer = d3.timer(render); invalidation.then(() => (timer.stop(), timer = null, d3.select(canvas).on(".drag", null))); return canvas; }31:[{"id":"49711e112c90952075e0e3d19410df2f2b068997e153ea383fe394c4aa6bf7bc149738d1faa95a6c02188c81c39402c5b7bd32da7a4d5f5732f8eaf30caf2489","href":"https://static.observableusercontent.com/files/49711e112c90952075e0e3d19410df2f2b068997e153ea383fe394c4aa6bf7bc149738d1faa95a6c02188c81c39402c5b7bd32da7a4d5f5732f8eaf30caf2489","name":"iceland.tiff","type":"image/tiff","lastModified":1645057022554.446,"size":1425688},{"id":"7b6ff41e373e01d7b5b95773e297d40625bd9ccc1936a023a066a7edd8da5eaadec4ab7a565303539e41e001f2e6730f3ee1e259fae4f19dc59e8d6b2f2ec22b","href":"https://static.observableusercontent.com/files/7b6ff41e373e01d7b5b95773e297d40625bd9ccc1936a023a066a7edd8da5eaadec4ab7a565303539e41e001f2e6730f3ee1e259fae4f19dc59e8d6b2f2ec22b","name":"land-50m.json","type":"application/json","lastModified":1645057197331.253,"size":545534}] 2d:{"title":"GeoTIFF Contours II","cells":[{"id":0,"value":"md`# GeoTIFF Contours II\n\nThese contours are computed in equirectangular coordinates and then reprojected.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":127,"value":"viewof a = slider({\n min: -180, \n max: 180, \n step: 1, \n value: 10, \n title: \"rotation\"\n})","pinned":false,"hidden":false,"mode":"ojs"},{"id":131,"value":"viewof tilt = slider({\n min: -40, \n max: 40, \n step: 1, \n value: -12, \n title: \"tilt\"\n})","pinned":false,"hidden":false,"mode":"ojs"},{"id":268,"value":"viewof land_color = Inputs.color({label: \"Land color\", value: \"#e6e6e6\"})","pinned":false,"hidden":false,"mode":"ojs"},{"id":31,"value":"chart = html``","pinned":true,"hidden":false,"mode":"ojs"},{"id":217,"value":" //${Array.from(contours(values), d => svg``)}","pinned":true,"hidden":false,"mode":"ojs"},{"id":214,"value":"sea_contours = Array.from(contours(values)).map( invert )","pinned":true,"hidden":false,"mode":"ojs"},{"id":283,"value":"sea_contours2 = sea_contours.map(function(p) {\n return p.type == \"Polygon\" ? simplify(p, .25) : p;\n})","pinned":true,"hidden":false,"mode":"ojs"},{"id":306,"value":"console.log( JSON.stringify(sea_contours2) )","pinned":true,"hidden":false,"mode":"ojs"},{"id":38,"value":"//projection = d3.geoEqualEarth().rotate([a,0])//NaturalEarth1().precision(0.1)","pinned":true,"hidden":false,"mode":"ojs"},{"id":203,"value":"projection = d3.geoOrthographic().rotate([a,tilt])//NaturalEarth1().precision(0.1)","pinned":true,"hidden":false,"mode":"ojs"},{"id":33,"value":"path = d3.geoPath(projection)","pinned":true,"hidden":false,"mode":"ojs"},{"id":29,"value":"contours = d3.contours().size([n, m])","pinned":true,"hidden":false,"mode":"ojs"},{"id":184,"value":"simp_values = Array.from(contours(values)).map( invert ).map(function(p) {\n return p.type == \"Polygon\" ? simplify(p, .25) : p;\n})","pinned":true,"hidden":false,"mode":"ojs"},{"id":279,"value":"unsimp_values = Array.from(contours(values)).map( invert )","pinned":true,"hidden":false,"mode":"ojs"},{"id":281,"value":"JSON.stringify( unsimp_values ).length","pinned":true,"hidden":false,"mode":"ojs"},{"id":276,"value":"JSON.stringify( simp_values ).length","pinned":true,"hidden":false,"mode":"ojs"},{"id":301,"value":"console.log(JSON.stringify( simp_values ))","pinned":true,"hidden":false,"mode":"ojs"},{"id":235,"value":"Array.from(contours(values))","pinned":true,"hidden":false,"mode":"ojs"},{"id":142,"value":"buckets = d3.ticks(extent[0], extent[1], 20)","pinned":true,"hidden":false,"mode":"ojs"},{"id":27,"value":"color = d3.scaleDiverging(t => d3.interpolateRdBu(1 - t))\n .domain([extent[0], 0, 1.75])","pinned":true,"hidden":false,"mode":"ojs"},{"id":111,"value":"extent = d3.extent(values)","pinned":true,"hidden":false,"mode":"ojs"},{"id":16,"value":"image = tiff.getImage()","pinned":true,"hidden":false,"mode":"ojs"},{"id":15,"value":"values = (await image.readRasters())[0].map( d => isNaN(d) ? 0 : d < -1.75 ? -1.75 : d)","pinned":true,"hidden":false,"mode":"ojs"},{"id":24,"value":"n = image.getWidth()","pinned":true,"hidden":false,"mode":"ojs"},{"id":167,"value":"isize = n","pinned":true,"hidden":false,"mode":"ojs"},{"id":22,"value":"m = image.getHeight()","pinned":true,"hidden":false,"mode":"ojs"},{"id":169,"value":"jsize = m","pinned":true,"hidden":false,"mode":"ojs"},{"id":47,"value":"md`The *rotate* function rotates a GeoTIFF’s longitude from ${tex`[0, 360]`} to ${tex`[-180, +180]`}.`","pinned":false,"hidden":false,"mode":"ojs"},{"id":42,"value":"function rotate(values) {\n var l = n >> 1;\n for (var j = 0, k = 0; j < m; ++j, k += n) {\n values.subarray(k, k + l).reverse();\n values.subarray(k + l, k + n).reverse();\n values.subarray(k, k + n).reverse();\n }\n return values;\n}","pinned":true,"hidden":false,"mode":"ojs"},{"id":50,"value":"md`The *invert* function converts [*x*, *y*] in pixel coordinates to [*longitude*, *latitude*]. This assumes the source GeoTIFF is in equirectangular coordinates.\n\nInverting the projection breaks the polygon ring associations: holes are no longer inside their exterior rings. Fortunately, since the winding order of the rings is consistent and we’re now in spherical coordinates, we can just merge everything into a single polygon!`","pinned":false,"hidden":false,"mode":"ojs"},{"id":45,"value":"$2f","pinned":false,"hidden":false,"mode":"ojs"},{"id":157,"value":"polygons = contours(values).map(invert).map(function(p) {\n return p.type == \"Polygon\" ? simplify(p, 0.01) : p;\n})","pinned":true,"hidden":false,"mode":"ojs"},{"id":123,"value":"$30","pinned":false,"hidden":false,"mode":"ojs"},{"id":98,"value":"outline = ({type: \"Sphere\"})","pinned":true,"hidden":false,"mode":"ojs"},{"id":96,"value":"graticule = d3.geoGraticule10()","pinned":true,"hidden":false,"mode":"ojs"},{"id":94,"value":"land = topojson.feature(world, world.objects.land)","pinned":true,"hidden":false,"mode":"ojs"},{"id":13,"value":"tiff = FileAttachment(\"iceland.tiff\").arrayBuffer()\n .then(buffer => GeoTIFF.fromArrayBuffer(buffer))","pinned":true,"hidden":false,"mode":"ojs"},{"id":165,"value":"function topdown(values) {\n var v = new Float32Array(values);\n for (var j = 0; j < jsize; j++) {\n for (var i = 0; i < isize; i++) {\n v[ (jsize-1-j) * isize + i ] = values[ j * isize + i ];\n }\n }\n return v;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":171,"value":"// torus: copy left column to the right\nfunction cylinder(values) {\n var v = new Float32Array(jsize * (isize+1));\n for (var j = 0; j < jsize; j++) {\n for (var i = 0; i < isize + 1; i++) {\n v[ j * (isize+1) + i ] = values[ j * isize + i%isize ];\n }\n }\n return v;\n}","pinned":false,"hidden":false,"mode":"ojs"},{"id":160,"value":" function simplify(polygon, s) {\n var topology = topojson.topology({polygon: polygon});\n topology = topojson.simplify(topojson.presimplify(topology), s);\n topology = topojson.filter(topology, r => topology.arcs[r[0]].length > 2);\n var p = topojson.feature(topology, topology.objects.polygon);\n p.value = polygon.value;\n return p;\n }","pinned":true,"hidden":false,"mode":"ojs"},{"id":6,"value":"GeoTIFF = require(\"geotiff@1.0.0-beta.13\")","pinned":true,"hidden":false,"mode":"ojs"},{"id":5,"value":"d3 = require(\"d3@6\", \"d3-geo-projection@3\")","pinned":true,"hidden":false,"mode":"ojs"},{"id":308,"value":"d3.scaleDiverging\n","pinned":true,"hidden":false,"mode":"ojs"},{"id":92,"value":"world = FileAttachment(\"land-50m.json\").json()","pinned":true,"hidden":false,"mode":"ojs"},{"id":90,"value":"topojson = require('topojson')","pinned":true,"hidden":false,"mode":"ojs"},{"id":125,"value":"import {slider} from \"@jashkenas/inputs\"","pinned":true,"hidden":false,"mode":"ojs"}],"files":"$W31","stdlib":"1","titling":"auto"}