I'm trying to put a marker at the center point of these coordinates. After calculating the bounds, I use getCenter() to give me the coordinates. But it returns "LatLng(-93.20448, 38.902475)" in longitude latitude direction, so using them in the marker doesn't work. It needs lat lon. I realize I'm not understanding something but what is it that I don't understand.
var bounds = L.latLngBounds([[-94.778092, 39.967458], [-91.630869, 39.967458], [-91.630869, 37.8374921], [-94.778092, 37.8374921], [-94.778092, 39.967458]]);
var middle = bounds.getCenter(); alert(middle); // LatLng(-93.20448, 38.902475)
var mk5 = new L.marker(new L.latLng( 38.902475, -93.20448 );
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If I pass latlnglastPosition to my widget, it's fine. I can see latitude and longitude and the value changes with zero lag as my camera position changes. However, using anything more than that causes crazy lag. It's practically unusable. Does anybody know what's causing this or if there's a better way of doing this? I'm trying to display latitude, longitude, altitude, distance from center versus current position in meters and miles. Here's the code:
void _onCameraMove(CameraPosition cameraPosition) async {
Position position = await Geolocator()
.getCurrentPosition(desiredAccuracy: LocationAccuracy.high);
lat = position.latitude;
lng = position.longitude;
alt = position.altitude;
_distancebetween = await Geolocator().distanceBetween(
_lastMapPosition.latitude, _lastMapPosition.longitude, lat, lng);
distancebetweenFinal = _distancebetween.toStringAsFixed(2);
distancebetweenFinalMiles = _distancebetween * (0.000621371);
_lastMapPosition = cameraPosition.target;
var latlnglastPosition = _lastMapPosition;
_currentZoom = cameraPosition.zoom;
setState(() {
latlnglastPosition;
distancebetweenFinal;
distancebetweenFinalMiles;
_distancebetween;
_lastMapPosition;
});
}
This is using Flutter Google Maps.
Edit: I removed the conversion from meters to miles. It didn't help. I don't think the altitude is having any impact. It's just going from current camera view position to my current position that's delaying everything. Is there perhaps a way to increase the frequency i receive location info? maybe that's hanging things up.... ?
Edit: or maybe I can use get last known position when a new location is not available? Not sure if that's the best way to handle this
Edit: I set lat = 34.0; lng = 34.0; and it's super fast now. However, it doesn't solve my problem. I need lat and lng to reflect my current position, and it seems i'm either restricted in pulling my current position or it's too costly to pull it as frequently as I need to. I don't know the best way to handle this... Any ideas are appreciated.
I got it (I think):
I replaced
Position position = await Geolocator()
.getCurrentPosition(desiredAccuracy: LocationAccuracy.high);
with:
Position position = await Geolocator().getLastKnownPosition();
I think position.latitude and position.longitude were too costly before. So, I'm getting the last known position. If anyone knows a better way, please let me know.
I have a map with 20 markers on a geojson layer. They are all from the same SVG and represent a certain area on the map (meaning they represent a circle of constant radius in meter on the map). I need these marker to adapt their size according to zoom level.
I've tried to use a circle as a marker. But my marker needs to be a SVG because it is complex graphic and radius doesn't apply to markers.
Here's the piece of code used to display the markers. Latitude, Longitude and rotationAngle are parsed from a .csv sheet:
for (i in chapters) {
var c = chapters[i];
if (!isNaN(parseFloat(c['Latitude'])) && !isNaN(parseFloat(c['Longitude']))) {
var lat = parseFloat(c['Latitude']);
var lon = parseFloat(c['Longitude']);
var cercleDirection = parseFloat(c['Direction']);
var photoIcon = L.icon({
iconUrl: 'media/Cercle.svg',
iconSize: [220, 220],
iconAnchor: [110, 110],
});
markers.push(
L.marker([lat, lon], {
icon: photoIcon,
rotationAngle: cercleDirection
}));
}
I have a Leaflet based mapping solution that uses ArcGIS map configuration supplied by a user (I have no idea what it will be, they will customize it with their own ArcGIS services). The issue is that the projection can be pretty much anything, and I will need to use Proj4Leaflet to configure the CRS of the map accordingly. The problem I'm running into is I'm not sure how to calculate the scale/resolution array. The user is inputting these values: projection key, Proj4 string, origin, bounds, zoom levels.
So, for example (yes I know EPSG:3857 is standard and I could just use L.CRS.EPSG3857 but it serves as a good example of how to set the same thing up using Proj4Leaflet):
Projection key = EPSG:3857
Proj4 string = +proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=#null +wktext +no_defs
Origin = [0,0]
Bounds = [[-20026376.39, -20048966.10], [20026376.39, 20048966.10]]
Zoom levels = 18
With that I think I have enough to set up a L.Proj.CRS for it:
var crs = new L.Proj.CRS("EPSG:3857", "+proj=merc +a=6378137 +b=6378137 +lat_ts=0.0 +lon_0=0.0 +x_0=0.0 +y_0=0 +k=1.0 +units=m +nadgrids=#null +wktext +no_defs",
{
resolutions : [?????],
origin : [0,0],
bounds : [[-20026376.39, -20048966.10], [20026376.39, 20048966.10]]
});
I have everything I need apart from the resolutions array, I am not sure exactly how to go about setting that up based on the data given and having a hard time finding answers to get me pointed in the right direction.
So bottom line, the only way I found to calculate resolutions is if it is a mercator projection and we know the longitude extents of it and the tile size. Otherwise the resolutions will need to be looked up at the ArcGIS Server tile server REST endpoint. Thus for my project I will need the user to supply the array themselves and cannot calculate it for them.
In the case of the mercator projection, I came up with this function that does the trick:
function parseResolutionsFromZoomLevels(zoomLevels, tileSize, mapWGS84Extent)
{
var metersPerExtent = 40075008/360;
var mapWGS84Meters = mapWGS84Extent*metersPerExtent;
var resolutionArray = [];
for (var i=0; i<zoomLevels; i++)
{
var tilesAtZoom = Math.pow(2,i);
var pixelsAtZoom = tilesAtZoom*tileSize;
resolutionArray.push(mapWGS84Meters/pixelsAtZoom);
}
return resolutionArray;
}
Hope this helps anyone else that happens to encounter this same situation.
I am working with the leaflet api.Where User draw a polyline and latlongs saved in variables.
I been looking for a leaflet function which suppose to take latlongs and calculate pixels.Found the layerPoint function but as i have low understanding of leaflet, can't use the function.
I have used 2 variables to store two latlng parameter, but didn't understand how to use them in layerPoint function.
Script
var polyline = new L.Polyline([]);
var aa;
var bb;
function getDist(e) {
// New marker on coordinate, add it to the map
// Add coordinate to the polyline
polyline.addLatLng(e.latlng).addTo(map).bindPopup();
var ccc = prompt('1st or 2nd');
if (ccc == '1') { aa = e.latlng}
else if (ccc == '2') { bb = e.latlng; convertIt();
}
}
function convertIt(e)
{
var getit = e.latLngToPoint(latlng, map.getZoom());
}
If someone can help, please do help.thanks for your time
latLngToPoint is a method on L.Map. You need to pass a latLng as a parameter to your convertIt function, then return map.latLngToPoint(e), assuming you keep e as the parameter name for convertIt.
I've been playing with the google earth API. I thought it would be neat to draw some lines between places from a relative 3D viewpoint. I've searched through the GE documentation and searched on google for answers but didn't find anything that led me down the correct path, so I thought I'd post some code and perhaps get some insight.
The following code plots two places and then draws a line between those places. Unfortunately the line that gets drawn splices the earth. Is there a method to make it wrap to the contour of the earth when drawn in 3D like this? I've attempted to vary the line height placement with a varying degree of success, but at the cost of accuracy and overall visual appeal when the line doesn't appear to connect the places.
function init() {
google.earth.createInstance('map3d', initCB, failureCB);
}
function initCB(instance) {
ge = instance;
ge.getWindow().setVisibility(true);
//---------------------------------PLACES
// Create the placemark.
var placemark = ge.createPlacemark('');
placemark.setName("Location 1");
// Set the placemark's location.
var point = ge.createPoint('');
point.setLatitude(39.96028);
point.setLongitude(-82.979736);
placemark.setGeometry(point);
// Add the placemark to Earth.
ge.getFeatures().appendChild(placemark);
// Create the placemark.
var placemark2 = ge.createPlacemark('');
placemark2.setName("Hop #2");
// Set the placemark's location.
var point2 = ge.createPoint('');
point2.setLatitude(25.7615);
point2.setLongitude(-80.2939);
placemark2.setGeometry(point2);
// Add the placemark to Earth.
ge.getFeatures().appendChild(placemark2);
//---------------------------------FOCUS
var lookAt = ge.createLookAt('');
lookAt.setLatitude(39.96028);
lookAt.setLongitude(-82.979736);
lookAt.setRange(1000000.0);
lookAt.setAltitude(0);
lookAt.setTilt(45);
ge.getView().setAbstractView(lookAt);
//---------------------------------LINES
// Create the placemark
var lineStringPlacemark = ge.createPlacemark('');
// Create the LineString
var lineString = ge.createLineString('');
lineStringPlacemark.setGeometry(lineString);
// Add LineString points
lineString.getCoordinates().pushLatLngAlt(39.96028, -82.979736, 0);
lineString.getCoordinates().pushLatLngAlt(25.7615, -80.2939, 0);
//lineString.setAltitudeMode(ge.ALTITUDE_CLAMP_TO_GROUND);
//lineString.setAltitudeMode(ge.ALTITUDE_RELATIVE_TO_GROUND);
lineString.setAltitudeMode(ge.absolute);
// Create a style and set width and color of line
lineStringPlacemark.setStyleSelector(ge.createStyle(''));
var lineStyle = lineStringPlacemark.getStyleSelector().getLineStyle();
lineStyle.setWidth(2);
lineStyle.getColor().set('9900ffff'); // aabbggrr format
// Add the feature to Earth
ge.getFeatures().appendChild(lineStringPlacemark);
}
function failureCB(errorCode) {
}
google.setOnLoadCallback(init);
You will want to set tesselation, and optionally extrude, on your linestring to true.
See https://developers.google.com/kml/documentation/kmlreference#tessellate and https://developers.google.com/kml/documentation/kmlreference#extrude for details
For the API, your syntax would be something like
lineStringPlacemark.setTessellate(true);
lineStringPlacemark.setExtrude(true);
There's some additional API examples on this at https://developers.google.com/earth/documentation/geometries