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I want to create a bounding box for a geolocation in Swift which returns to me (minY maxY minX maxX) Is there a function to do this in Swift?
iOS doesn't have the idea of a bounding box, but it does have a region struct called MKCoordinateRegion.
MKCoordinateRegion contains two things:
CLLocationCoordinate2D center;
MKCoordinateSpan span;
Both are structs. The span contains the height and width of the region. Using those you can make a bounding box (from here)
CLLocationCoordinate2D centerCoord = CLLocationCoordinate2DMake(41.145495, −73.994901);
MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(centerCoord, 2000, 2000);
double latMin = region.center.latitude - .5 * startRegion.span.latitudeDelta;
double latMax = region.center.latitude + .5 * startRegion.span.latitudeDelta;
double lonMin = region.center.longitude - .5 * startRegion.span.longitudeDelta;
double lonMax = region.center.longitude + .5 * startRegion.span.longitudeDelta;
Edit: I just realised the request was for Swift. I'll leave translation as an exercise for bonus points.
Related
I have been searching on this thing from long time.
Is there any math formula to convert miles or meters to pixel for zoom level in google map? Any kind of help is appreciated. I am currently working for iOS.
I found a solution from here https://gist.github.com/ryanhanwu/4dbcdbdf384f5a3cca1f
I re-wrote it for Swift 4 as below
let topLeft: CLLocationCoordinate2D = mapView.projection.visibleRegion().farLeft
let bottomLeft: CLLocationCoordinate2D = mapView.projection.visibleRegion().nearLeft
let zoom = mapView.camera.zoom
let lat = Double(fabs(Float(topLeft.latitude - bottomLeft.latitude)))
let metersPerPixel: Double = Double((cos(lat * .pi / 180) * 2 * .pi) * 6378137 / Double((256 * pow(2, zoom))))
In my iOS app I have a lat and long that gives me my location. I want to be able to calculate the bounding box that satisfies a certain distance d from my location. How can I do this?
TRY 1:
So I tried the solution given by #Neeku. I can see how it's supposed to return the right information but unfortunately it's off. So I don't think I can use it.
The code I wrote is this and I pass in 1000 meters:
MKCoordinateRegion startRegion = MKCoordinateRegionMakeWithDistance(center, meters, meters);
CLLocationCoordinate2D northWestCorner, southEastCorner;
northWestCorner.latitude = startRegion.center.latitude + .5 * startRegion.span.latitudeDelta;
northWestCorner.longitude = startRegion.center.longitude - .5 * startRegion.span.longitudeDelta;
southEastCorner.latitude = startRegion.center.latitude - .5 * startRegion.span.latitudeDelta;
southEastCorner.longitude = startRegion.center.longitude - .5 * startRegion.span.longitudeDelta;
NSLog(#"CENTER <%#,%#>", #(center.latitude),#(center.longitude));
NSLog(#"NW <%#,%#>, SE <%#,%#>",#(northWestCorner.latitude),#(northWestCorner.longitude),#(southEastCorner.latitude),#(southEastCorner.longitude));
So then the result is:
CENTER <38.0826682,46.3028721>
NW <38.08717278501047,46.29717303828632>, SE <38.07816361498953,46.29717303828632>
I then put that in google maps and get this: (see screenshot)
So then to my understanding the 1000 meters should go from the center to the sides of the box. The map is measuring the corner which should be OVER 1000 meters and it's actually just over 800 meters. This is the problem I am trying to solve.
I tried this method before and the distances simply aren't accurate. So, this solution has not worked for me. If you have more suggestions or maybe want to point out what is done wrong here please let me know.
Thank you
Let's say that your desired distance is 111 meters. Then you use the following code:
// 111 kilometers / 1000 = 111 meters.
// 1 degree of latitude = ~111 kilometers.
// 1 / 1000 means an offset of coordinate by 111 meters.
float offset = 1.0 / 1000.0;
float latMax = location.latitude + offset;
float latMin = location.latitude - offset;
// With longitude, things are a bit more complex.
// 1 degree of longitude = 111km only at equator (gradually shrinks to zero at the poles)
// So need to take into account latitude too, using cos(lat).
float lngOffset = offset * cos(location.latitude * M_PI / 180.0);
float lngMax = location.longitude + lngOffset;
float lngMin = location.longitude - lngOffset;
latMax, latMin, lngMax, lngMin will give you your bounding box coordinates.
(You can change this code pretty easily if you need distance other than 111 meters. Just update offset variable accordingly).
You can add/subtract half of the span from the latitude and longitude respectively and you get the values that you need:
CLLocationCoordinate2D centerCoord = CLLocationCoordinate2DMake(38.0826682, 46.3028721);
MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(centerCoord, 1000, 1000);
double latMin = region.center.latitude - .5 * startRegion.span.latitudeDelta;
double latMax = region.center.latitude + .5 * startRegion.span.latitudeDelta;
double lonMin = region.center.longitude - .5 * startRegion.span.longitudeDelta;
double lonMax = region.center.longitude + .5 * startRegion.span.longitudeDelta;
Just remember that:
latitudeDelta
The amount of north-to-south distance (measured in degrees) to display on the map. Unlike longitudinal distances, which vary based on
the latitude, one degree of latitude is always approximately 111
kilometers (69 miles).
longitudeDelta
The amount of east-to-west distance (measured in degrees) to display for the map region. The number of kilometers spanned by a
longitude range varies based on the current latitude. For example, one
degree of longitude spans a distance of approximately 111 kilometers
(69 miles) at the equator but shrinks to 0 kilometers at the poles.
I want to calculate the distance between 2 lat & long. I am able to calculate the distance as below
CLLocation *currentLoc = [[CLLocation alloc] initWithLatitude:-24.4132995 longitude:121.0790024];
CLLocation *restaurnatLoc = [[CLLocation alloc] initWithLatitude:-32.8310013 longitude:150.1390075];
CLLocationDistance meters = [restaurnatLoc distanceFromLocation:currentLoc];
NSLog(#"Distance between 2 geo cordinates: %.2f Meters",meters);
Now I want to get the direction from currentLocation to restaurnatLoc. For this I have below code
double DegreesToRadians(double degrees) {return degrees * M_PI / 180;};
double RadiansToDegrees(double radians) {return radians * 180/M_PI;};
-(double) bearingToLocationFromCoordinate:(CLLocation*)fromLoc toCoordinate:(CLLocation*)toLoc
{
double lat1 = DegreesToRadians(fromLoc.coordinate.latitude);
double lon1 = DegreesToRadians(fromLoc.coordinate.longitude);
double lat2 = DegreesToRadians(toLoc.coordinate.latitude);
double lon2 = DegreesToRadians(toLoc.coordinate.longitude);
double dLon = lon2 - lon1;
double y = sin(dLon) * cos(lat2);
double x = cos(lat1) * sin(lat2) - sin(lat1) * cos(lat2) * cos(dLon);
double radiansBearing = atan2(y, x);
return RadiansToDegrees(radiansBearing);
}
It returns bearing = 114.975752 Now how can I decide whether restaurant is in North,South,West,East,NW,NE,SW,SE from my current location ?
I get 1 solution from this link Direction based off of 2 Lat,Long points But if I consider this solution , then I have doubt on bearing 114 from my location(red circle) to restaurant (green circle) as shown below. Correct me if I am wrong.
As current location is "Western Australia" & restaurant location is "Sydney" as shown in Google Maps.
Can any body tell me whats going wrong here ? Thanks.
///////////////////////////// Update /////////////////////////////
My compass diagram is wrong. Here is the correct diagram all thanks to AlexWien
Now I am getting the correct output
your compass rose is totally wrong. have you ever looked at a compass? open the iphone compass app and look where 90Degrees is located. It is east, not west like in your graphic.
geographical direction is measured clockwise!
so 114 deg is east, which matches you expectation
I am working with an API that allows me to specify a "bounding box" of coordinate which allows me to only return results within that box:
Returns a list of geocaches inside the specified bounding box sorted
by the distance from the center of the box.
The parameters south
latitude, west longitude, north latitude, east longitude define the
edges of a bounding box.
Coordinates should be in decimal degrees Use
positive numbers for north latitude and east longitude and negative
numbers of south latitude and west longitude.
The box cannot cross
the 180° longitude line or the 90° or -90° points.
The math for this is a little beyond me, but I found somewhat helpful calculations, but I am not sure it is what I need for the API:
MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(self.mapView.centerCoordinate, 2000.0, 2000.0);
CLLocationCoordinate2D northWestCorner, southEastCorner;
northWestCorner.latitude = center.latitude - (region.span.latitudeDelta / 2.0);
northWestCorner.longitude = center.longitude + (region.span.longitudeDelta / 2.0);
southEastCorner.latitude = center.latitude + (region.span.latitudeDelta / 2.0);
southEastCorner.longitude = center.longitude - (region.span.longitudeDelta / 2.0);
Does anyone know how I could do this? Are the calculations here not helpful in order to get the west longitude, north latitude, east longitude that define the edges of the bounding box?
EDIT:
The error I am getting:
Invalid value for parameter: bbox=south,west,north,east
Using the center value:
center=37.552821,-122.377413
Converted Box (after calculations from above):
bbox=37.561831,-122.388730,37.543811,-122.366096
Final Working code:
// Current distance
MKMapRect mRect = mapView.visibleMapRect;
MKMapPoint eastMapPoint = MKMapPointMake(MKMapRectGetMinX(mRect), MKMapRectGetMidY(mRect));
MKMapPoint westMapPoint = MKMapPointMake(MKMapRectGetMaxX(mRect), MKMapRectGetMidY(mRect));
CLLocationDistance distance = MKMetersBetweenMapPoints(eastMapPoint, westMapPoint);
// Region
MKCoordinateRegion region = MKCoordinateRegionMakeWithDistance(request.center, distance, distance);
CLLocationCoordinate2D northWestCorner, southEastCorner;
northWestCorner.latitude = request.center.latitude + (region.span.latitudeDelta / 2.0);
northWestCorner.longitude = request.center.longitude - (region.span.longitudeDelta / 2.0);
southEastCorner.latitude = request.center.latitude - (region.span.latitudeDelta / 2.0);
southEastCorner.longitude = request.center.longitude + (region.span.longitudeDelta / 2.0);
base = [base stringByAppendingFormat:#"bbox=%f,%f,%f,%f&", southEastCorner.latitude,northWestCorner.longitude,northWestCorner.latitude,southEastCorner.longitude];
You seem to have gotten your hemispheres reversed. North and east are positive. So if you start from the center latitude and you want to find the northern boundary you ADD half the delta, not subtract.
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How to make objects move in circular motion from (startX,startY) to (destinationX, destinationY) with some aberration using TweenLite [actionscript 3 library]?
You should be able to set a circular motion using the CirclePath2D plugin and maybe offset the location a bit with an onUpdate function.
The bit that sounds confusing is
from (startX,startY) to (destinationX, destinationY)
because if you move in a circular motion, at some point you end where you started from.
if you start from one position and end in another, you might move on a curve, in which case you want to have a look at the BezierThroughPlugin.
Still, it's fairly straight forward to animate on a circle path with an onEnterFrame loop and you can easily change the circle into an oval for example or randomly offset the path a bit. Normally you'd need to convert from polar to cartesian coordinates:
x = cos(angle) * radius
y = sin(angle) * radius
but Point's polar() method already does that for you:
var speed:Number = 0;//how fast to move around the circle
var spread:Number = 20;//how far away from the centre
var b:Sprite = addChild(new Sprite()) as Sprite;
b.graphics.beginFill(0);
b.graphics.drawCircle(-3,-3,3);
b.graphics.endFill();
graphics.lineStyle(1,0xDEDEDE);
this.addEventListener(Event.ENTER_FRAME,update);
function update(event:Event):void{
speed += .1;//update the 'angle' , .1 is the increment/speed at which b spins
var distance:Number = spread + (Math.random() * 10 - 5);//spread + random 'aberration'
var offset:Point = Point.polar(distance,speed);//convert from angle/radius to x,y
b.x = mouseX + offset.x;
b.y = mouseX + offset.y;
graphics.lineTo(b.x,b.y);
}