Add vectortile branch

2015-09-10 15:23:57 +02:00
parent 57ee7f52fd
commit 962473c3ab
3201 changed files with 978141 additions and 0 deletions
@@ -0,0 +1,191 @@
+var minVgi = 0;
+var maxVgi = 0.25;
+var bins = 10;
+
+
+/**
+ * Calculate the Vegetation Greenness Index (VGI) from an input pixel.  This
+ * is a rough estimate assuming that pixel values correspond to reflectance.
+ * @param {ol.raster.Pixel} pixel An array of [R, G, B, A] values.
+ * @return {number} The VGI value for the given pixel.
+ */
+function vgi(pixel) {
+  var r = pixel[0] / 255;
+  var g = pixel[1] / 255;
+  var b = pixel[2] / 255;
+  return (2 * g - r - b) / (2 * g + r + b);
+}
+
+
+/**
+ * Summarize values for a histogram.
+ * @param {numver} value A VGI value.
+ * @param {Object} counts An object for keeping track of VGI counts.
+ */
+function summarize(value, counts) {
+  var min = counts.min;
+  var max = counts.max;
+  var num = counts.values.length;
+  if (value < min) {
+    // do nothing
+  } else if (value >= max) {
+    counts.values[num - 1] += 1;
+  } else {
+    var index = Math.floor((value - min) / counts.delta);
+    counts.values[index] += 1;
+  }
+}
+
+
+/**
+ * Use aerial imagery as the input data for the raster source.
+ */
+var bing = new ol.source.BingMaps({
+  key: 'Ak-dzM4wZjSqTlzveKz5u0d4IQ4bRzVI309GxmkgSVr1ewS6iPSrOvOKhA-CJlm3',
+  imagerySet: 'Aerial'
+});
+
+
+/**
+ * Create a raster source where pixels with VGI values above a threshold will
+ * be colored green.
+ */
+var raster = new ol.source.Raster({
+  sources: [bing],
+  operation: function(pixels, data) {
+    var pixel = pixels[0];
+    var value = vgi(pixel);
+    summarize(value, data.counts);
+    if (value >= data.threshold) {
+      pixel[0] = 0;
+      pixel[1] = 255;
+      pixel[2] = 0;
+      pixel[3] = 128;
+    } else {
+      pixel[3] = 0;
+    }
+    return pixel;
+  },
+  lib: {
+    vgi: vgi,
+    summarize: summarize
+  }
+});
+raster.set('threshold', 0.1);
+
+function createCounts(min, max, num) {
+  var values = new Array(num);
+  for (var i = 0; i < num; ++i) {
+    values[i] = 0;
+  }
+  return {
+    min: min,
+    max: max,
+    values: values,
+    delta: (max - min) / num
+  };
+}
+
+raster.on('beforeoperations', function(event) {
+  event.data.counts = createCounts(minVgi, maxVgi, bins);
+  event.data.threshold = raster.get('threshold');
+});
+
+raster.on('afteroperations', function(event) {
+  schedulePlot(event.resolution, event.data.counts, event.data.threshold);
+});
+
+var map = new ol.Map({
+  layers: [
+    new ol.layer.Tile({
+      source: bing
+    }),
+    new ol.layer.Image({
+      source: raster
+    })
+  ],
+  target: 'map',
+  view: new ol.View({
+    center: [-9651695, 4937351],
+    zoom: 13,
+    minZoom: 12,
+    maxZoom: 19
+  })
+});
+
+
+var timer = null;
+function schedulePlot(resolution, counts, threshold) {
+  if (timer) {
+    clearTimeout(timer);
+    timer = null;
+  }
+  timer = setTimeout(plot.bind(null, resolution, counts, threshold), 1000 / 60);
+}
+
+var barWidth = 15;
+var plotHeight = 150;
+var chart = d3.select('#plot').append('svg')
+    .attr('width', barWidth * bins)
+    .attr('height', plotHeight);
+
+var chartRect = chart[0][0].getBoundingClientRect();
+
+var tip = d3.select(document.body).append('div')
+    .attr('class', 'tip');
+
+function plot(resolution, counts, threshold) {
+  var yScale = d3.scale.linear()
+      .domain([0, d3.max(counts.values)])
+      .range([0, plotHeight]);
+
+  var bar = chart.selectAll('rect').data(counts.values);
+
+  bar.enter().append('rect');
+
+  bar.attr('class', function(count, index) {
+    var value = counts.min + (index * counts.delta);
+    return 'bar' + (value >= threshold ? ' selected' : '');
+  })
+  .attr('width', barWidth - 2);
+
+  bar.transition().attr('transform', function(value, index) {
+    return 'translate(' + (index * barWidth) + ', ' +
+        (plotHeight - yScale(value)) + ')';
+  })
+  .attr('height', yScale);
+
+  bar.on('mousemove', function(count, index) {
+    var threshold = counts.min + (index * counts.delta);
+    if (raster.get('threshold') !== threshold) {
+      raster.set('threshold', threshold);
+      raster.changed();
+    }
+  });
+
+  bar.on('mouseover', function(count, index) {
+    var area = 0;
+    for (var i = counts.values.length - 1; i >= index; --i) {
+      area += resolution * resolution * counts.values[i];
+    }
+    tip.html(message(counts.min + (index * counts.delta), area));
+    tip.style('display', 'block');
+    tip.transition().style({
+      left: (chartRect.left + (index * barWidth) + (barWidth / 2)) + 'px',
+      top: (d3.event.y - 60) + 'px',
+      opacity: 1
+    });
+  });
+
+  bar.on('mouseout', function() {
+    tip.transition().style('opacity', 0).each('end', function() {
+      tip.style('display', 'none');
+    });
+  });
+
+}
+
+function message(value, area) {
+  var acres = (area / 4046.86).toFixed(0).replace(/\B(?=(\d{3})+(?!\d))/g, ',');
+  return acres + ' acres at<br>' + value.toFixed(2) + ' VGI or above';
+}