Develop Reference

How can I pass a geometry to the Map function in GEE?

I am trying to use the Map function in Google Earth Engine to clip an ImageCollection to a geometry. I have multiple areas of interest (AOIs) and thus would like to apply a generic clip function multiple times (for each AOI). However, when I create a function with two parameters (the image and the geometry) to map over, I get the error image.clip is not a function. When using the function with just one parameter (the image), it works just fine, but then I need to write two (or possible more) functions to do exactly the same task (i.e. clipping an image to a certain geometry).
I have tried the solutions in this post, but they do not work.
Any ideas on how to solve this issue?
Code:
// Get NTL data
var ntl = ee.ImageCollection("NOAA/VIIRS/DNB/MONTHLY_V1/VCMSLCFG");
// Define start and end year
var startYear = 2015;
var endYear = 2018;
// Filter montly and select 'avg_rad' band
var ntlMonthly = ntl.filter(ee.Filter.calendarRange(startYear, endYear, 'year'))
.filter(ee.Filter.calendarRange(1,12,'month'))
.select(['avg_rad']);
// Create geometries of AOIs
// -- Create a geometry of Venezuela
var geomVenezuela = ee.Geometry.Rectangle([-73.341258, 13.363291, -59.637555, -0.372893]);
// -- Create a geometry of Caracas (Venezuela's capital)
var geomCaracas = ee.Geometry.Rectangle([-67.062383, 10.558489, -66.667078, 10.364908]);
// Functions to crop to Venezuela (nationwide) and Caracas (local) resp.
var clipImageToGeometry = function(image, geom) {
return image.clip(geom);
}
// Apply crop function to the ImageCollection
var ntlMonthly_Venezuela = ntlMonthly.map(clipImageToGeometry.bind(null, geomVenezuela));
var ntlMonthly_Caracas = ntlMonthly.map(clipImageToCaracas.bind(null, geomCaracas));
// Convert ImageCollection to single Image (for exporting to Drive)
var ntlMonthly_Venezuela_image = ntlMonthly_Venezuela.toBands();
var ntlMonthly_Caracas_image = ntlMonthly_Caracas.toBands();
// Check geometry in map
Map.addLayer(geomCaracas, {color: 'red'}, 'planar polygon');
Map.addLayer(ntlMonthly_Caracas_image);
// Store scale (m. per pixel) in variable
var VenezuelaScale = 1000;
var CaracasScale = 100;
// Export the image, specifying scale and region.
Export.image.toDrive({
image: ntlMonthly_Caracas_image,
description: 'ntlMonthly_Caracas_'.concat(startYear, "_to_", endYear),
folder: 'GeoScripting',
scale: CaracasScale,
fileFormat: 'GeoTIFF',
maxPixels: 1e9
});

If I understood your question correctly:
If you want to crop each image in the ImageCollection to a geometry, you could just do
var ntlMonthly_Venezuela = ntlMonthly.map(function(image){return ee.Image(image).clip(geomVenezuela)})
And just repeat for other AOIs.
If you wan to cast it into a function:
var clipImageCollection = function(ic, geom){
return ic.map(function(image){return ee.Image(image).clip(geom)})
}
// Apply crop function to the ImageCollection
var ntlMonthly_Venezuela = clipImageCollection(ntlMonthly, geomVenezuela);
var ntlMonthly_Caracas = clipImageCollection(ntlMonthly, geomCaracas);

Google maps setPaths from getPaths coordinates

I'm trying to get the Paths of a polygon, and then set them to another polygon like that.
newpoly = new google.maps.Polygon({
paths:poly.getPaths()
});
Isn't this suppose to work ? It gives me this error in the console.
Invalid value for constructor parameter 0: [object Object]

Try adding the following before you instantiate the polygon object
var triangleCoords = [
new google.maps.LatLng(25.774252, -80.190262),
new google.maps.LatLng(18.466465, -66.118292),
new google.maps.LatLng(32.321384, -64.75737),
new google.maps.LatLng(25.774252, -80.190262)
];
Now use you code and replace the poly.getPaths() - Assuming the rest of your code works.
newpoly = new google.maps.Polygon({
paths:triangleCoords //there are probably more method to add here
});
If it works then you know there is something wrong with poly.getPaths(). Use this as reference https://developers.google.com/maps/documentation/javascript/overlays#PolygonOptions.
Remember that we can only use the code that was provide to formulate an solution.

It would help if you can show the code for poly object and if poly.getPaths() return anything. All I can recomand si to debug it in detail like this:
Do you hace any error if you comment paths:poly:Paths();
Console.log(poly); return a google map polygon?
Console.log(poly.getPaths()) return an array of paths?
If yes, you can try to create an array from poly.getPaths then pass it to newpoly.

Get the coords of first polygon this way (assuming that the two polygons were already created):
//store polygon path
var vertices = firstPolygon.getPath();
// Iterate over the vertices.
pathOfFirstPolygon = [];
for (var i =0; i < vertices.getLength(); i++) {
var xy = vertices.getAt(i);
item = {};
item["lat"] = xy.lat();
item["lng"] = xy.lng();
pathOfFirstPolygon.push(item);
};
//Set path of the second polygon
secondPolygon.setPath(pathOfFirstPolygon);

ArcGIS Javascript - Zoom to show all points

I am trying to add some functionality that will zoom the map in/out depending on the points that are returned from a query. So for example, say we're zoomed in on the state of Texas. If I execute a query and the service returns back points that are in Texas AND some located in California, I would like the map to then zoom out and then display both California and Texas. I have been looking through the ArcGIS JS API to see how I could implement it but I'm having trouble figuring out what properties and/or methods to use to accomplish this.

The FeatureSet provided to the QueryTask's onComplete callback has the property features that is an array of Graphics.
The javascript api provides the esri.graphicsExtent(graphics) function that can accept that array of Graphics and calculate their extent. Once the extent has been calculated, map.setExtent(extent) can be used to zoom the map to that extent.
It should be noted that the documentation for esri.graphicsExtent(...) specifies that 'If the extent height and width are 0, null is returned.' This case will occur if the returned Graphics array only has a single point in it, so you'll want to check for it.
Here's an example QueryTask onComplete callback that could be used to zoom the map to the extents of points returned by the query:
function onQueryComplete(returnedPointFeatureSet){
var featureSet = returnedPointFeatureSet || {};
var features = featureSet.features || [];
var extent = esri.graphicsExtent(features);
if(!extent && features.length == 1) {
// esri.getExtent returns null for a single point, so we'll build the extent by hand by subtracting/adding 1 to create x and y min/max values
var point = features[0];
extent = new esri.geometry.Extent(point.x - 1, point.y - 1, point.x + 1, point.y + 1, point.spatialReference);
}
if(extent) {
// assumes the esri map object is stored in the globally-scoped variable 'map'
map.setExtent(extent)
}
}

I agree, map.setExtent(extent, true) is the way to go here. Another observation: In case we have only a single point it's worth considering simply using map.centerAndZoom(point, ZOOM_LEVEL) instead of creating an extent. Then, we could just have this:
function onQueryComplete(returnedPointFeatureSet){
var featureSet = returnedPointFeatureSet || {};
var features = featureSet.features || [];
var extent = esri.graphicsExtent(features);
if(!extent && features.length == 1) {
var point = features[0];
map.centerAndZoom(point, 12);
}
else {
map.setExtent(extent, true);
}
}

Not a good idea to create an extent from a point that way. If the units are in degrees you could get a huge extent. Instead, you could do a buffer around the point using the geometryEngine
function onQueryComplete(featureSet){
if (featureSet.features.length) {
var extent = esri.graphicsUtils.graphicsExtent(featureSet.features);
if(!extent && featureSet.features.length == 1 && featureSet.features[0].geometry.type == "point") {
var point = featureSet.features[0];
var extent = esri.geometry.geometryEngine.buffer(point.geometry, 1, "meters").getExtent();
}
// assumes the esri map object is stored in the globally-scoped variable 'map'
map.setExtent(extent)
}
}

Get distance in pixels between 2 LonLat objects in OpenLayers

I have 2 OpenLayers.LonLat objects, and I want to determine the distance in pixels for the current zoom between the 2. I'm using OpenLayers.Layer.getViewPortPxFromLonLat() to determine the x and y of the points and then subtract to see the difference between the 2, but the values that I get are very small for points that are 2000km apart.
Here is my code:
var center_lonlat = new OpenLayers.LonLat(geometry.lon, geometry.lat);
var center_px = layer.getViewPortPxFromLonLat(center_lonlat);
var radius_m = parseFloat(feature.attributes["radius"]);
var radius_lonlat = OpenLayers.Util.destinationVincenty(center_lonlat, 0, radius_m);
var radius_px = layer.getViewPortPxFromLonLat(radius_lonlat);
var radius = radius_px.y - center_px.y;
I'm trying here to draw a circle, giving that I receive a center point and a radius in meters. The LonLat object seems to be ok.
Am I doing something wrong ?

I found the issue: destinationVincenty() need and returns coordinates in wgs84 where my map was using spherical mercator projection.
I hope I got correctly the answer, because projections make me dizzy and never really understood them :(. I was looking in the console to the numbers for my coordinates and the coordinates from the map.getExtent() that is used to calculate the getViewPortPxFromLonLat() and I realised they are not in the right order of magnitude, and then it hit me.
So, the code is now:
var spherical_mercator = new OpenLayers.Projection("EPSG:900913");
var wgs84 = new OpenLayers.Projection("EPSG:4326");
var map = feature.layer.map;
var geometry = feature.geometry;
var center_lonlat = new OpenLayers.LonLat(geometry.y, geometry.x);
var center_px = map.getViewPortPxFromLonLat(center_lonlat);
var radius_m = parseFloat(feature.attributes["radius"]);
var radius_lonlat = OpenLayers.Util.destinationVincenty(center_lonlat.clone().transform(spherical_mercator, wgs84), 0, radius_m).transform(wgs84, spherical_mercator);
var radius_px = map.getViewPortPxFromLonLat(radius_lonlat);
var radius = Math.abs(radius_px.y - center_px.y);
Measured the circles with the OpenLayers.Control.ScaleLine, and the size is dead on :D

You seem to be doing right. If the distance you get is too small, maybe there is a problem with OpenLayers.Util.destinationVincenty function? Have you tried to replace the bearing (0) with anything else - its value seem to be not important in your case. But frankly speaking, I wasn't able to understand how it works while browsing the source

Adding Panoramio Photos To An OpenLayers Map

I have a pretty well integrated OpenLayers map that I want to add photos from the Panoramio API to. Unfortunately, it seems both API's are under documented on this subject. I found one great tutorial here http://www.gisandchips.org/2010/05/04/openlayers-y-panoramio/ but as I am new to all of this, could be why I cannot complete this on my own. I feel like even using this tutorial I have a lot of blank spaces in my mind and not to mention, the photos are NOT appearing on my map :-/
Here is my portion of the code that demonstrates my use of that tutorial and what I have attempted so far:
var url = "http://www.panoramio.com/map/get_panoramas.php";
var parameters = {
order: 'popularity',
set: 'full',
from: 0,
to: 20,
minx: 84.05,
miny: 31.36,
maxx: 91.89,
maxy: 32.30,
size: 'thumbnail'
} //end parameters
OpenLayers.loadURL(url, parameters, this, displayPhotos);
function displayPhotos(response) {
var json = new OpenLayers.Format.JSON();
var panoramio = json.read(response.responseText);
var features = new Array(panoramio.photos.length);
for (var i = 0; i < panoramio.photos.length; i++) {
var upload_date = panoramio.photos[i].upload_date;
var owner_name = panoramio.photos[i].owner_name;
var photo_id = panoramio.photos[i].photo_id;
var longitude = panoramio.photos[i].longitude;
var latitude = panoramio.photos[i].latitude;
var pheight = panoramio.photos[i].height;
var pwidth = panoramio.photos[i].width;
var photo_title = panoramio.photos[i].photo_title;
var owner_url = panoramio.photos[i].owner_url;
var owner_id = panoramio.photos[i].owner_id;
var photo_file_url = panoramio.photos[i].photo_file_url;
var photo_url = panoramio.photos[i].photo_url;
var fpoint = new OpenLayers.Geometry.Point(longitude, latitude);
var attributes = {
'upload_date': upload_date,
'owner_name': owner_name,
'photo_id': photo_id,
'longitude': longitude,
'latitude': latitude,
'pheight': pheight,
'pwidth': pwidth,
'pheight': pheight,
'photo_title': photo_title,
'owner_url': owner_url,
'owner_id': owner_id,
'photo_file_url': photo_file_url,
'photo_url': photo_url
} //end attributes
features[i] = new OpenLayers.Feature.Vector(fpoint, attributes);
} //end for
var panoramio_style2 = new OpenLayers.StyleMap(OpenLayers.Util.applyDefaults({
pointRadius: 7,
fillColor: "red",
fillOpacity: 1,
strokeColor: "black",
externalGraphic: "panoramio-marker.png"
}, OpenLayers.Feature.Vector.style["default"]));
var vectorPano = new OpenLayers.Layer.Vector("Panoramio Photos", {
styleMap: panoramio_style2
});
vectorPano.addFeatures(features);
map.addLayer(vectorPano);
} //end displayPhotos
In my mind this code should work perfectly. Giving me a result of some Panoramio thumbnails on my slippy map. Unfortunately it seems that the layer is there, but blank..When I look at the response text in Firebug I can see that the JSON is returned with attributes of photos from Panoramio, in the location I have specified (Tibet). I appreciate your help and time to consider my issues.
Thank you,
elshae

I don't know how proficient you are in OpenLayers, but the project is certainly not underdocumented. There is an extensive api documentation and also numerous examples that should help to get you started.
But now back to your problem: likely, this is a projection issue. Panoramio returns WSG-84 (GPS) Coordinates for all the photos it found, and the openstreetmap baselayer of your map is in Spherical Mercator projection ('EPSG:900913').
So you have to convert the coordinates from WSG-84 to Spherical Mercator using something like
var curPic = panoramio.photos[i];
var panLonLat = new OpenLayers.LonLat(curPic.longitude, curPic.latitude);
panLonLat.transform(new OpenLayers.Projection("EPSG:4326"), new OpenLayers.Projection('EPSG:900913'));
and then use the converted point for your geometry