Develop Reference

Implementing Heat Map on Google Maps using a combination of langitutde, altitude and Energy consumption

I'm using android studio to create a heat map on google maps. I have a database consisting of the following information:
longitude latitude Electricity Energy Consumption
1 -77.08527 38.7347905 4.742112594
2 -19.03592 34.8081915 4.742112594
3 -74.04591 12.8815925 5.278542493
4 -32.05547 25.9549935 12.270006486
5 -49.06596 76.0283945 4.742112594
6 -63.08492 20.1017955 4.742112594
Is there any way to take these coordinates and magnitude and plot a density map using Google Maps?
I've done a bit of research, and the google api does allow the creation of the heatmap but it only allows a dataset containing coordiantes. How would I reflect the energy consumption in certain areas?
This is the link to the site that tells you how to create a heatmap: https://developers.google.com/maps/documentation/android-api/utility/heatmap
I just need a push in the right direction to be able to implement this.
There is the following method that I thought I could use but I didnt quite understand it and was hoping maybe someone could explain how to use it, and if its possible to use this to implement my particular scenario:
This is the code from the site to implement the heatmap which only take into account the coordinates:
List<LatLng> list = null;
// Get the data: latitude/longitude positions of police stations.
try {
list = readItems(R.raw.police_stations);
} catch (JSONException e) {
Toast.makeText(this, "Problem reading list of locations.", Toast.LENGTH_LONG).show();
}
// Create a heat map tile provider, passing it the latlngs of the police stations.
mProvider = new HeatmapTileProvider.Builder()
.data(list)
.build();
// Add a tile overlay to the map, using the heat map tile provider.
mOverlay = mMap.addTileOverlay(new TileOverlayOptions().tileProvider(mProvider));
}
private ArrayList<LatLng> readItems(int resource) throws JSONException {
ArrayList<LatLng> list = new ArrayList<LatLng>();
InputStream inputStream = getResources().openRawResource(resource);
String json = new Scanner(inputStream).useDelimiter("\\A").next();
JSONArray array = new JSONArray(json);
for (int i = 0; i < array.length(); i++) {
JSONObject object = array.getJSONObject(i);
double lat = object.getDouble("lat");
double lng = object.getDouble("lng");
list.add(new LatLng(lat, lng));
}
return list;
}
This is the code from the site to change the dataset:
ArrayList<WeightedLatLng> data = new ArrayList<WeightedLatLng>();
mProvider.setData(data);
mOverlay.clearTileCache();

Instead of LatLng, you can use WeightedLatLng.
You code should look like:
List<WeightedLatLng> list = null;
// Get the data: latitude/longitude positions of police stations.
try {
list = readItems(R.raw.police_stations);
} catch (JSONException e) {
Toast.makeText(this, "Problem reading list of locations.", Toast.LENGTH_LONG).show();
}
// Create a heat map tile provider, passing it the latlngs of the police stations.
mProvider = new HeatmapTileProvider.Builder()
.weightedData(list)
.build();
// Add a tile overlay to the map, using the heat map tile provider.
mOverlay = mMap.addTileOverlay(new
TileOverlayOptions().tileProvider(mProvider));
}
private List<WeightedLatLng> readItems(int resource) throws JSONException {
List<WeightedLatLng> list = new ArrayList<WeightedLatLng>();
InputStream inputStream = getResources().openRawResource(resource);
String json = new Scanner(inputStream).useDelimiter("\\A").next();
JSONArray array = new JSONArray(json);
for (int i = 0; i < array.length(); i++) {
JSONObject object = array.getJSONObject(i);
double lat = object.getDouble("lat");
double lng = object.getDouble("lng");
double magnitude = object.getDouble("mag"
list.add(new WeightedLatLng(lat, lng, magnitude));
}
return list;
}

How to create an open polyline in GeoTools 12-RC1?

I need to create a GeoJSON stream, which contains data about roads. The roads are like polygons, except they are open (the start and end points are different).
I tried to use the following code to achieve that goal:
protected void addPolyLine(final double[] coords,
final GeometryBuilder builder,
final SimpleFeatureBuilder fbuilder,
final List<SimpleFeature> features,
final String id) {
final double[] modcoords = new double[coords.length+2];
for (int i=0; i < coords.length; i++) {
modcoords[i] = coords[i];
}
modcoords[modcoords.length-2] = coords[0];
modcoords[modcoords.length-1] = coords[1];
final double[] holeStart = new double[] {coords[0], coords[1],
coords[coords.length-2], coords[coords.length - 1]};
final LinearRing shell = builder.linearRing(modcoords);
final LinearRing hole = builder.linearRing(holeStart);
final Polygon polygon = builder.polygon(shell, hole);
fbuilder.add(polygon);
final SimpleFeature feature = fbuilder.buildFeature(id);
features.add(feature);
}
It doesn't work - I get the error
java.lang.IllegalArgumentException: Invalid number of points in LinearRing (found 3 - must be 0 or >= 4)
at com.vividsolutions.jts.geom.LinearRing.validateConstruction(LinearRing.java:114)
at com.vividsolutions.jts.geom.LinearRing.<init>(LinearRing.java:106)
at com.vividsolutions.jts.geom.GeometryFactory.createLinearRing(GeometryFactory.java:341)
at org.geotools.geometry.jts.GeometryBuilder.linearRing(GeometryBuilder.java:199)
When I use builder.lineString(coords), the resulting GeoJSON contains no coordinates as it should.
How can I create a polyline (a line, which connects several point and is not closed) using GeoTools 12-RC1?
Update 1 (05.07.2015 21:22 MSK): This is how I define feature types for points, polygons and lines. Points and polygons work fine, lines don't.
private final static SimpleFeatureType POINT =
createType("Test", "Location:Point");
private final static SimpleFeatureType POLYGON =
createType("Test2", "Location:Polygon");
private final BuildingsReader buildingsReader =
new DefaultBuildingsReader();
private final static SimpleFeatureType LINE =
createType("Test3", "Line");
private static SimpleFeatureType createType(final String x1, final String x2) {
try
{
return DataUtilities.createType(x1, x2);
}
catch (final SchemaException exception) {
exception.printStackTrace();
}
return null;
}

You need to do something with createLineString like:
line=builder.createLineString(Arrays.asList(coords));
fbuilder.add(line);
final SimpleFeature feature = fbuilder.buildFeature(id);
features.add(feature);
You will need to modify your feature type to expect a line instead of a polygon.

Extract polygon geometry from citygml data using citygml4j library

I have buildings' information stored in citygml file. I am trying to extract the building's polygon geometry using the citygml4j library. I have looked at the FeatureWalker class, but I am unable to get the polygon geometry.
How do I go about doing this? Here is my code:
CityGMLContext ctx = new CityGMLContext();
CityGMLBuilder builder = ctx.createCityGMLBuilder();
CityGMLInputFactory in = builder.createCityGMLInputFactory();
CityGMLReader reader = in.createCityGMLReader(new File("/home/vishal/NWW/sampleData/LOD2_Building_v100.gml"));
while(reader.hasNext())
{
CityGML citygml = reader.nextFeature();
System.out.println("Found class:" + citygml.getCityGMLClass() + "\nVersion"+citygml.getCityGMLModule().getVersion());
//Counting the no of buildings
CityModel citymodel = new CityModel();
if(citygml.getCityGMLClass() == CityGMLClass.CITY_MODEL)
{
citymodel = (CityModel)citygml;
// Counting the no of buildings
int count=0;
for(CityObjectMember cityObjectMember : citymodel.getCityObjectMember())
{
AbstractCityObject cityobject = cityObjectMember.getCityObject();
if(cityobject.getCityGMLClass() == CityGMLClass.BUILDING)
{
++count;
}
}
System.out.println("Building count"+count);
}
FeatureWalker walker = new FeatureWalker(){
public void visit(Building building){
System.out.println(building.getId());
//MultiSurface multisurface = boundrysurface.getLod2MultiSurface().getMultiSurface();
//System.out.println(multisurface.getSurfaceMember().get(0));
List<BoundarySurfaceProperty> list = building.getBoundedBySurface();
System.out.println(list);
System.out.println(list.get(0).getBoundarySurface());
//HOW TO GET THE POLYGON AND ITS COORDINATES??
}
};
citymodel.accept(walker);
PS: If you have any other resources/tutorials on citygml4j library, kindly let me know.
Thanks,

You can search for the AbstractBoundarySurfaces directly, like this:
FeatureWalker walker = new FeatureWalker() {
#Override
public void visit(AbstractBoundarySurface boundarySurface) {
MultiSurfaceProperty lod2MultiSurface = boundarySurface.getLod2MultiSurface();
if (lod2MultiSurface != null) {
MultiSurface multiSurface = lod2MultiSurface.getMultiSurface();
if (multiSurface == null) {
// Do something!
}
List<SurfaceProperty> surfaceMember = multiSurface.getSurfaceMember();
for (SurfaceProperty surfaceProperty : surfaceMember) {
AbstractSurface abstractSurface = surfaceProperty.getObject();
if (abstractSurface instanceof Polygon) {
Polygon polygon = (Polygon) abstractSurface;
// Do something with polygon!
}
// Check for other subtypes of AbstractSurface
}
}
// Process LOD3 and LOD4
super.visit(boundarySurface);
}
};
building.accept(walker);
Then you can traverse down the tree and look for the polygons.

GeoTools: Saving grid to shp file

I am very new to GeoTools. I would like to create a hex grid and save it to a SHP file. But something goes wrong along the way (the saved SHP file is empty). In the debug mode I found that the gird is correctly created and contains a bunch of polygons that make sense. Writing those to a shape file proves to be difficult. I followed the tutorial on GeoTools' website, but that does not quite do it yet. I suspect TYPE to be incorrectly defined, but could not find out how to define it correctly.
Any help of how to store the grid into a SHP file is highly appreciated.
ReferencedEnvelope gridBounds = new ReferencedEnvelope(xMin, xMax, yMin, yMax, DefaultGeographicCRS.WGS84);
// length of each hexagon edge
double sideLen = 0.5;
// max distance between vertices
double vertexSpacing = sideLen / 20;
SimpleFeatureSource grid = Grids.createHexagonalGrid(gridBounds, sideLen, vertexSpacing);
/*
* We use the DataUtilities class to create a FeatureType that will describe the data in our
* shapefile.
*
* See also the createFeatureType method below for another, more flexible approach.
*/
final SimpleFeatureType TYPE = createFeatureType();
/*
* Get an output file name and create the new shapefile
*/
File newFile = new File("D:/test/shape.shp");
ShapefileDataStoreFactory dataStoreFactory = new ShapefileDataStoreFactory();
Map<String, Serializable> params = new HashMap<String, Serializable>();
params.put("url", newFile.toURI().toURL());
params.put("create spatial index", Boolean.TRUE);
ShapefileDataStore newDataStore = (ShapefileDataStore) dataStoreFactory.createNewDataStore(params);
newDataStore.createSchema(TYPE);
/*
* You can comment out this line if you are using the createFeatureType method (at end of
* class file) rather than DataUtilities.createType
*/
newDataStore.forceSchemaCRS(DefaultGeographicCRS.WGS84);
/*
* Write the features to the shapefile
*/
Transaction transaction = new DefaultTransaction("create");
String typeName = newDataStore.getTypeNames()[0];
SimpleFeatureSource featureSource = newDataStore.getFeatureSource(typeName);
if (featureSource instanceof SimpleFeatureStore) {
SimpleFeatureStore featureStore = (SimpleFeatureStore) featureSource;
featureStore.setTransaction(transaction);
try {
featureStore.addFeatures(grid.getFeatures());
transaction.commit();
} catch (Exception problem) {
problem.printStackTrace();
transaction.rollback();
} finally {
transaction.close();
}
} else {
System.out.println(typeName + " does not support read/write access");
}
private static SimpleFeatureType createFeatureType() {
SimpleFeatureTypeBuilder builder = new SimpleFeatureTypeBuilder();
builder.setName("Location");
builder.setCRS(DefaultGeographicCRS.WGS84); // <- Coordinate reference system
// add attributes in order
builder.add("Polygon", Polygon.class);
builder.length(15).add("Name", String.class); // <- 15 chars width for name field
// build the type
final SimpleFeatureType LOCATION = builder.buildFeatureType();
return LOCATION;
}

How can I set altitudeMode in KML encoding with GeoTools?

I am exporting a set of points to KML using the GeoTools KML encoder.
It works fine, but my points are expressed as lat, lon, alt, and they are exported as such, but Google Earth presents them clamped to the surface.
I read here that I need to set the altitudeMode attribute. How would I do that with the GeoTools encoder?
Here's my code:
/**
* Converts the given point array to KML.
* #param points The array of points to be converted.
* #param os The target output stream where the resulting KML is to be
* written. This method does not close the stream.
*/
public static void toKml(Point[] points, OutputStream os) {
SimpleFeatureTypeBuilder sftb = new SimpleFeatureTypeBuilder();
sftb.setName("points");
sftb.add("geomtery", Point.class, DefaultGeographicCRS.WGS84_3D);
SimpleFeatureType type = sftb.buildFeatureType();
DefaultFeatureCollection features = new DefaultFeatureCollection();
SimpleFeatureBuilder builder = new SimpleFeatureBuilder(type);
for (int i = 0; i < points.length; i++) {
builder.add(points[i]);
features.add(builder.buildFeature(Integer.toString(i)));
}
Encoder encoder = new Encoder(new KMLConfiguration());
encoder.setIndenting(true);
try {
encoder.encode(features, KML.kml, os);
} catch (IOException e) {
throw new RuntimeException("While converting " +
Arrays.toString(points) + " to KML.", e);
}
}