pnavarrc/Makefile

## README.md

      
    Raw
  

              README.md
            
          
    Celestial Sphere

This gist demonstrate how to create a celestial sphere using the orthographic projection.
Data

This gist uses a subset of the stars visible to the naked eye from the combined catalog HYG Databse. To generate the subset, run the command:
make hyg.json


## hyg.json

      
Display the source blob

    
Display the rendered blob

    
    Raw
  

              hyg.json
            
          
      Sorry, something went wrong. Reload?
      Sorry, we cannot display this file.
      Sorry, this file is invalid so it cannot be displayed.
      
          Viewer requires iframe.
      
    
## index.html
<html>
<head>
    <title>Celestial Sphere</title>
    <link rel="stylesheet" type="text/css" href="styles.css">
    <script src="http://d3js.org/d3.v3.min.js" charset="utf-8"></script>
</head>
<body>

    <div id="map"></div>

    <script type="text/javascript">

        // Set the width and height of the SVG container
        var width = 400,
            height = 400;

        // Select the container div and append the SVG element
        var div = d3.select('#map'),
            svg = div.append('svg').attr('width', width).attr('height', height),
            grp = svg.append('g').attr('class', 'gmap');

        // Add a lighting effect to give the circle a spherical aspect
        var filter = svg.append('filter').attr('id', 'lightMe');

        filter.append('feDiffuseLighting')
            .attr('in', 'SourceGraphic')
            .attr('result', 'light')
            .attr('lighting-color', 'white')
            .append('fePointLight')
                .attr('x', 0.85 * width)
                .attr('y', 0.85 * height)
                .attr('z', 50);

        filter.append('feComposite')
            .attr('in', 'SourceGraphic')
            .attr('in2', 'light')
            .attr('operator', 'arithmetic')
            .attr('k1', '1')
            .attr('k2', '0')
            .attr('k3', '0')
            .attr('k4', '0');

        // Projectioon and Path Generator
        // ------------------------------

        // Store the current rotation
        var rotate = {x: 0, y: 90};

        // Create and configure an instance of the orthographic projection
        var projection = d3.geo.orthographic()
            .scale(width / 2)
            .translate([width / 2, height / 2])
            .clipAngle(90)
            .rotate([rotate.x / 2, -rotate.y / 2]);

        // Create and configure the geographic path generator
        var path = d3.geo.path().projection(projection);

        // Overlay
        // -------
        var overlay = svg.selectAll('circle').data([rotate])
            .enter().append('circle')
            .attr('transform', 'translate(' + [width / 2, height / 2] + ')')
            .attr('r', width / 2)
            .attr('filter', 'url(#lightMe)')
            .attr('class', 'overlay');

        // Globe Outline
        // -------------
        var globe = grp.selectAll('path.globe').data([{type: 'Sphere'}])
            .enter().append('path')
            .attr('class', 'globe')
            .attr('d', path);

        // Graticule
        // ---------
        var graticule = d3.geo.graticule();

        // Draw graticule lines
        grp.selectAll('path.graticule').data([graticule()])
            .enter().append('path')
            .attr('class', 'graticule')
            .attr('d', path);

        // Load the stellar catalog
        d3.json('hyg.json', function(error, data) {

            // Handle errors getting and parsing the data
            if (error) { return error; }

            // Compute the radius scale. The radius will be proportional to
            // the aparent magnitude
            var rScale = d3.scale.linear()
                .domain(d3.extent(data.features, function(d) { return d.properties.mag; }))
                .range([3, 1]);

            // Compute the radius for the point features
            path.pointRadius(function(d) {
                return d.properties ? rScale(d.properties.mag) : 1;
            });

            // Stars
            // -----
            grp.selectAll('path.star').data(data.features)
                .enter().append('path')
                .attr('class', 'star')
                .attr('d', path);

            // Drag Behavior
            // -------------
            var dragBehavior = d3.behavior.drag()
                .origin(Object)
                .on('drag', function(d) {
                    projection.rotate([(d.x = d3.event.x) / 2, -(d.y = d3.event.y) / 2]);
                    svg.selectAll('path').attr('d', function(u) {
                        // The circles are not properly generated when the
                        // projection has the clipAngle option set.
                        return path(u) ? path(u) : 'M 10 10';
                    });
                });

            // Add the drag behavior to the overlay
            overlay.call(dragBehavior);
        });
    </script>
</body>
</html>

## Makefile
hygfull.csv:
	curl -LO 'https://github.com/astronexus/HYG-Database/raw/master/hygfull.csv'

hyg.json: hygfull.csv
	python parse-catalog.py

## parse-catalog.py
import csv
import json
import os

class CSVReader:
    """Iterate through the rows of the CSV file.

    The iterator returns a dictionary with the column names as keys. The
    values of the dictionary are strings, they may need to be casted.
    """

    def __init__(self, csvpath):

        self.csvfile = open(csvpath, 'r')
        self.reader = csv.reader(self.csvfile, delimiter=',')
        self.header = self.reader.next()

    def __iter__(self):

        return self

    def next(self):
        """Returns a dictionary with column names as keys and the cell contents
        as values. The values are strings.

        """

        # Retrieve the next row from the file.
        try:
            row = self.reader.next()
        except StopIteration:
            self.csvfile.close()
            raise

        item = dict()
        for ncol in range(len(row)):
            item[self.header[ncol]] = row[ncol]

        return item


if __name__ == '__main__':

    # Create the CSV reader
    reader = CSVReader('hygfull.csv')

    # The data will be stored as a feature collection
    feature = {'type': 'FeatureCollection', 'features': []}

    for row in reader:

        # Compute the magnitude and equivalent (ish) longitude and latitude
        mag = float(row['Mag'])
        lon = 360 * float(row['RA']) / 24 - 180
        lat = float(row['Dec'])

        # Store only the stars visible to the naked eye
        if (-1 < mag) and (mag < 5):
            feature['features'].append({
                'type': 'Feature',
                'properties': {'mag': mag},
                'geometry': {'type': 'Point', 'coordinates': [lon, lat]}
            })

    # Store the stars as a GeoJSON file
    jsonfile = open('hyg.json', 'w')
    json.dump(feature, jsonfile)
    jsonfile.close()


## styles.css
body {
    background-color: #eee;
}

#map {
    width: 400px;
    height: 400px;

    display: block;
    margin-left: auto;
    margin-right: auto;

    margin-top: 40px;
    margin-bottom: 10px;
}

.graticule {
    fill: none;
    stroke: #0053ad;
    stroke-width: 1px;
}

.globe {
    fill: #060061;
}

.star {
    fill: #fff;
    fill-opacity: 0.9;
}

.overlay {
    fill: #005fc7;
    fill-opacity: 0.4;
}

## thumbnail.png

      
    Raw
  

              thumbnail.png
	<html>
	<head>
	<title>Celestial Sphere</title>
	<link rel="stylesheet" type="text/css" href="styles.css">
	<script src="http://d3js.org/d3.v3.min.js" charset="utf-8"></script>
	</head>
	<body>

	<div id="map"></div>

	<script type="text/javascript">

	// Set the width and height of the SVG container
	var width = 400,
	height = 400;

	// Select the container div and append the SVG element
	var div = d3.select('#map'),
	svg = div.append('svg').attr('width', width).attr('height', height),
	grp = svg.append('g').attr('class', 'gmap');

	// Add a lighting effect to give the circle a spherical aspect
	var filter = svg.append('filter').attr('id', 'lightMe');

	filter.append('feDiffuseLighting')
	.attr('in', 'SourceGraphic')
	.attr('result', 'light')
	.attr('lighting-color', 'white')
	.append('fePointLight')
	.attr('x', 0.85 * width)
	.attr('y', 0.85 * height)
	.attr('z', 50);

	filter.append('feComposite')
	.attr('in', 'SourceGraphic')
	.attr('in2', 'light')
	.attr('operator', 'arithmetic')
	.attr('k1', '1')
	.attr('k2', '0')
	.attr('k3', '0')
	.attr('k4', '0');

	// Projectioon and Path Generator
	// ------------------------------

	// Store the current rotation
	var rotate = {x: 0, y: 90};

	// Create and configure an instance of the orthographic projection
	var projection = d3.geo.orthographic()
	.scale(width / 2)
	.translate([width / 2, height / 2])
	.clipAngle(90)
	.rotate([rotate.x / 2, -rotate.y / 2]);

	// Create and configure the geographic path generator
	var path = d3.geo.path().projection(projection);

	// Overlay
	// -------
	var overlay = svg.selectAll('circle').data([rotate])
	.enter().append('circle')
	.attr('transform', 'translate(' + [width / 2, height / 2] + ')')
	.attr('r', width / 2)
	.attr('filter', 'url(#lightMe)')
	.attr('class', 'overlay');

	// Globe Outline
	// -------------
	var globe = grp.selectAll('path.globe').data([{type: 'Sphere'}])
	.enter().append('path')
	.attr('class', 'globe')
	.attr('d', path);

	// Graticule
	// ---------
	var graticule = d3.geo.graticule();

	// Draw graticule lines
	grp.selectAll('path.graticule').data([graticule()])
	.enter().append('path')
	.attr('class', 'graticule')
	.attr('d', path);

	// Load the stellar catalog
	d3.json('hyg.json', function(error, data) {

	// Handle errors getting and parsing the data
	if (error) { return error; }

	// Compute the radius scale. The radius will be proportional to
	// the aparent magnitude
	var rScale = d3.scale.linear()
	.domain(d3.extent(data.features, function(d) { return d.properties.mag; }))
	.range([3, 1]);

	// Compute the radius for the point features
	path.pointRadius(function(d) {
	return d.properties ? rScale(d.properties.mag) : 1;
	});

	// Stars
	// -----
	grp.selectAll('path.star').data(data.features)
	.enter().append('path')
	.attr('class', 'star')
	.attr('d', path);

	// Drag Behavior
	// -------------
	var dragBehavior = d3.behavior.drag()
	.origin(Object)
	.on('drag', function(d) {
	projection.rotate([(d.x = d3.event.x) / 2, -(d.y = d3.event.y) / 2]);
	svg.selectAll('path').attr('d', function(u) {
	// The circles are not properly generated when the
	// projection has the clipAngle option set.
	return path(u) ? path(u) : 'M 10 10';
	});
	});

	// Add the drag behavior to the overlay
	overlay.call(dragBehavior);
	});
	</script>
	</body>
	</html>
	hygfull.csv:
	curl -LO 'https://github.com/astronexus/HYG-Database/raw/master/hygfull.csv'

	hyg.json: hygfull.csv
	python parse-catalog.py
	import csv
	import json
	import os

	class CSVReader:
	"""Iterate through the rows of the CSV file.

	The iterator returns a dictionary with the column names as keys. The
	values of the dictionary are strings, they may need to be casted.
	"""

	def __init__(self, csvpath):

	self.csvfile = open(csvpath, 'r')
	self.reader = csv.reader(self.csvfile, delimiter=',')
	self.header = self.reader.next()

	def __iter__(self):

	return self

	def next(self):
	"""Returns a dictionary with column names as keys and the cell contents
	as values. The values are strings.

	"""

	# Retrieve the next row from the file.
	try:
	row = self.reader.next()
	except StopIteration:
	self.csvfile.close()
	raise

	item = dict()
	for ncol in range(len(row)):
	item[self.header[ncol]] = row[ncol]

	return item


	if __name__ == '__main__':

	# Create the CSV reader
	reader = CSVReader('hygfull.csv')

	# The data will be stored as a feature collection
	feature = {'type': 'FeatureCollection', 'features': []}

	for row in reader:

	# Compute the magnitude and equivalent (ish) longitude and latitude
	mag = float(row['Mag'])
	lon = 360 * float(row['RA']) / 24 - 180
	lat = float(row['Dec'])

	# Store only the stars visible to the naked eye
	if (-1 < mag) and (mag < 5):
	feature['features'].append({
	'type': 'Feature',
	'properties': {'mag': mag},
	'geometry': {'type': 'Point', 'coordinates': [lon, lat]}
	})

	# Store the stars as a GeoJSON file
	jsonfile = open('hyg.json', 'w')
	json.dump(feature, jsonfile)
	jsonfile.close()
	body {
	background-color: #eee;
	}

	#map {
	width: 400px;
	height: 400px;

	display: block;
	margin-left: auto;
	margin-right: auto;

	margin-top: 40px;
	margin-bottom: 10px;
	}

	.graticule {
	fill: none;
	stroke: #0053ad;
	stroke-width: 1px;
	}

	.globe {
	fill: #060061;
	}

	.star {
	fill: #fff;
	fill-opacity: 0.9;
	}

	.overlay {
	fill: #005fc7;
	fill-opacity: 0.4;
	}