I am confused about the geonear query with mongoid. It seems that I am missing something and when I m trying to query for points near the given coordinates with max distance 200 meters form my controller with the following:
Coord.geo_near([params[:lon].to_i, params[:lat].to_i]).max_distance(200)
I get all the points that are available in the collection in the same order for every set of coords that i provide.
My model:
class Coord
include Mongoid::Document
include Mongoid::Geospatial
field :Message, :type => String
field :location, type: Point, spatial: true
end
I have created the 2dsphere index from mongo console:
db.coords.createIndex( { location : "2dsphere" } )
I have also tried instead of 200 meters to provide 0.2/111.2 in the case that the max_distance works with degrees but in this case I m not getting any results.
Use Earth radius
To search in 10km radius:
Coord.geo_near([params[:lon].to_f, params[:lat].to_f]).max_distance(10.fdiv(6_371))
Related
Good I have a database with records that have a latitude and longitude stored if as a radius in KM (it is the distance from your point which they want to be seen).
I have a use case that should provide a point (latitude and longitude) to return all the records that its radius matches the latitude and longitude of the search.
I have this code, but I can't get it, what it returns is in order the records closest to the search point (it would have to be the other way around). Return the records that your radio is in the latitude and longitude of the search.
const documents = await collection.find({
'location.point': {
$within: {
$centerSphere: [
[longitude, latitude],
10/6378.1
]
}
}
})
If anyone can help me with what I am doing wrong, I would appreciate it. I'm very lost.
I am trying find a solution on how to display polygons that are only within a specific range, a circle with radius using leaflet.
Polygons screenshots
Before, I have ask for help regarding on the display of points within a specific range but this time, since a polygon have many nodes/coordinates, i don't have any idea of how it can be done for polygons; a foreach statement?
Any solution? Thanks for the help!
Similar problem solved for displaying points within a specific range
Since you're using MongoDB, the best solution here is (if that's possible), to handle this in the database. Put 2dsphere indexes on your document's loc field and use a $geoWithin query in combination with $centerSphere:
The following example queries grid coordinates and returns all documents within a 10 mile radius of longitude 88 W and latitude 30 N. The query converts the distance to radians by dividing by the approximate radius of the earth, 3959 miles:
db.places.find( {
loc: { $geoWithin: { $centerSphere: [ [ -88, 30 ], 10/3959 ] } }
} )
2dsphere reference: http://docs.mongodb.org/manual/core/2dsphere/
$geoWithin reference: http://docs.mongodb.org/manual/reference/operator/query/geoWithin/
$centerSphere reference: http://docs.mongodb.org/manual/reference/operator/query/centerSphere/
If you really want to do this clientside (which i absolutely wouldn't recommend) and you don't want to build your on solution (which is possible) you could take a look at GeoScript.
GeoScript's geom.Geometry() class has a contains method:
Tests if this geometry contains the other geometry (without boundaries touching).
Geom.geometry reference: http://geoscript.org/js/api/geom/geometry.html
EDIT: Here's the pure JS/Leaflet solution as requested in the comments, this is quick-n-dirty, but it should work. Here the containsPolygon method returns true when all of the polygon's points are within the circle:
L.Circle.include({
'containsPoint': function (latLng) {
return this.getLatLng().distanceTo(latLng) < this.getRadius();
},
'containsPolygon': function (polygon) {
var results = [];
polygon.getLatLngs().forEach(function (latLng) {
results.push(this.containsPoint(latLng));
}, this);
return (results.indexOf(false) === -1);
}
});
Here's a working example: http://plnkr.co/edit/JlFToy?p=preview
If you want to return true if one or more of the polygon's points are within the circle than you must change the return statement to this:
return (results.indexOf(true) !== -1);
I have a documents contains list of location "boxes" (square area). Each box is represented by 2 points (bottom-left or south-west, top-right or north-east).
Document, for example:
{
locations: [
[[bottom,left],[top,right]],
[[bottom,left],[top,right]],
[[bottom,left],[top,right]]
]
}
I'm using 2d index for those boundaries points.
My input is a specific location point [x,y] and I want to fetch all documents that have at list one box that this point is located in it.
Is there any geospatial operator I can use to do that?
How do I write this query?
You can use the box operator, see:
http://docs.mongodb.org/manual/reference/operator/query/box/#op._S_box with the following example taken directly from that page:
db.places.find( { loc : { $geoWithin : { $box :
[ [ 0 , 0 ] ,
[ 100 , 100 ] ] } } } )
It is worth noting that the 2d index is considered legacy. If you can convert to using GeoJSON and a 2dsphere index, then you can use the $geoWithin operator: see
http://docs.mongodb.org/manual/reference/operator/query/geoWithin/#op._S_geoWithin
GeoJSON has a number of other benefits, not least of which, is that it is easily transmitted and digested by web mapping apps such as OpenLayers or Leaflet.
I am trying to order at list by nearest place. This is working fine with this code:
Cloud.Places.query({
page: 1,
per_page: 20,
where: {
lnglat: { '$nearSphere': [latitudefast,longitudefast], }
},
order: {
lnglat: { '$nearSphere': [latitudefast,longitudefast], }
},
latitudefast and longitudefast is representing the actual position on the user. It has be defined before the query.
But it is "upside down", which means that the nearest place is in the bottom of the list, and the one farthest away is at the top of the list! How come? How do I order in reverse? Am i ordering wrong?
Thanks!
Have you tried not specifying the order? $nearSphere by default returns results sorted by distance.
From MongoDB's documentation (which ACS uses as its data store) describing $near:
The above query finds the closest points to (50,50) and returns them
sorted by distance (there is no need for an additional sort
parameter).
This applies to $nearSphere as well.
http://www.mongodb.org/display/DOCS/Geospatial+Indexing
I am trying to get my head around MongoDB and geospatial searches.
Basically what I want is for users to be able to query documents (images) that
are shot within a set distance from the users current location. So I the user is searching for all images that are shot within 1 km from where he is standing I try to use
the below example but I have no idea what to set as the maxdistance value.
db.places.find({ loc : { $near : [50,50] , $maxDistance : 5 }})
So my question is what do I set as maxdistance if I am searching for documents
within a 1 km radius?
I am totally stuck here.
In order to use mongodb $near queries with km bounds, you need to convert the radius value to km. By default mongodb $near accepts $maxDistance as radius.
Convert distance by 111.12 (one degree is approximately 111.12 kilometers) when using km, or leave distance as it is on using degree
to your question
what do I set as maxdistance if I am searching for documents within a
1 km radius?
you can use this
db.places.find( { loc : { $near : [50,50] , $maxDistance : 1/111.12 } } )
I have answered how to use mongo geospatial features here in detail. You can check out
Since version 2.4 of MongoDB you can specify the radius directly in meters as a value of $maxDistance, like this:
db.<collection>.find({loc: {$near :
{$geometry :
{
type: 'Point',
coordinates: [<longitude> , <latitude>]
}
},
$maxDistance: 10*100
}
});
In recent versions I am using Spring and Mongo 4.0.5. Important thing is type of index and location data type. I am using 2dsphere,org.springframework.data.mongodb.core.geo.GeoJsonPoint
Later on it generate corresponding mongo query with geometry with distance in meters.
{ "location" : { "$nearSphere" : { "$geometry" : { "type" : "Point", "coordinates" : [18.341772, 43.834183] }, "$maxDistance" : 331.0 }