Get features in tile

The interactive API supports the following tile types:

  • web for the Mercator projection (used by OpenStreetMaps, Google Maps, Bing Maps and others) format: level_x_y; for example: 10_100_100 means level 10. x-coordinate 100, y-coordinate 100
  • tms for the Tile Map Service developed by the Open Source Geospatial Foundation format: level_x_y; for example: 10_100_100 means level 10 x-coordinate 100, * y-coordinate 100
  • quadkey for quadtree keys used by Bing Maps (formerly Virtual Earth) and others format: for example 0123031233 for level 10
  • here for the HERE tiling schema
GET /<Base path for the interactive API from the API Lookup Service>/layers/<Layer ID>/tile/<Tile Type>/<Tile ID>
Host: <Hostname for the interactive API from the API Lookup Service>
Authorization: Bearer <Authorization Token>
Cache-Control: no-cache

Note

For authorization in a GET request you can also use an API Key as a query parameter instead of a bearer token in an authorization header.

Response

{
    "type": "FeatureCollection",
    "features":
    [
        {
            "type": "Feature",
            "id": "BfiimUxHjj",
            "geometry":
            {
                "type": "Point",
                "coordinates":
                [
                    -2.960847,
                    53.430828
                ]
            },
            "properties":
            {
                "name": "Anfield",
                "@ns:com:here:xyz":
                {
                    "createdAt": 1517504700726,
                    "updatedAt": 1517504700726
                },
                "amenity": "Football Stadium",
                "capacity": 54074,
                "popupContent": "Home of Liverpool Football Club"
            }
        }
    ]
}

Get clustered features in a tile

This section describes how to get data from an interactive map layer in a clustered form. Two clustering modes are available: hexbin and quadbin.

  • hexbin - calculates the amount of features in a hexagonal tiling. Furthermore it provides statistics (min, max, avg, median) on a user-defined property.
  • quadbin - calculates the amount of features in tiles and subtiles. It gives a fast overview on dataset locations on lower zoom levels. The quadbins correspond to the webmercator tiling scheme.

Hexbin

While retrieving features from layers inside a tile you can use hexbin clustering to visualize your data as hexagons. Each hexagon represents the features of the area it covers. Additional statistical information about one property of your data can be evaluated and returned as properties of the returned hexagonal features.

The hexbin algorithm divides the world in hexagonal "bins" on a specified resolution. Each hexagon has an address being described by the H3 addressing scheme. For more information on that topic see: https://eng.uber.com/h3/

Fire data
Figure 1. Fire data

Request

GET /<Base path for the interactive API from the API Lookup Service>/layers/<Layer ID>/tile/<Tile Type>/<Tile ID>?clustering=hexbin&clustering.resolution=<#number>&clustering.property=<Property name>

The following clustering related parameters can be passed and combined with others ( e.g. tags, clip, feature filtering).

Parameter Type Mandatory Meaning
absoluteResolution Number No Integer, the H3 hexagon resolution [0,13], default:( s.b. Default Resolution for zoomlevel )
relativeResolution Number No Integer value [-2,2] to be added to current used resolution
property String No A property of the original features for which to calculate statistics
pointmode Boolean No returns the centroid of hexagons as geojson feature
singlecoord Boolean No evaluates the first object coordinate only (default: false)
sampling String No sampling ratio of the underlying dataset values [off, low, lowmed, med, medhigh, high] (default: off)
off ~ (1/1),
low ~ (1/8),
lowmed ~ (1/32),
med ~ (1/128),
medhigh ~ (1/1024),
high ~ (1/4096))

Response

{
    "type": "FeatureCollection",
    "features": [
        {
            "type": "Feature",
            "properties": {
                "kind" : "H3",
                "kind_detail" : "858b1303fffffff",
                "resolution": 5,
                "level": 7,
                "aggregation": {
                    "<Property name>": {  // only if a clustering.property=<Property name> is specified. If not specified field "qty" is
                                        // written on this object-level (e.g. properties.aggregation.qty )
                        "avg": 30.05000,
                        "max": 44.1,
                        "min": 16,
                        "qty": 2,
                        "sum": 60.1
                    }
                },
            "centroid": [ ... ], // only if clustering.pointmode = false|null
            "hexagon": [ ... ]  // only if clustering.pointmode = true
            },
            "geometry": {...},
        },
        ......
        ......
        {
            "type": "Feature",
            "properties": {
                "kind" : "H3",
                 "kind_detail" : "881f1d4a81fffff",
                    ....
            },
            "geometry": {...}
        }
    ]
}

Miscellaneous

Default Resolution for zoomlevel

The parameter clusterning.absoluteResolution specifies the size of the hexagons wanted (s. https://h3geo.org/docs/core-library/restable). The default resolution is balanced to suit size and performance of hexbin calculations per tile for normal amounts of data. Various parameters like amount, density, distribution and object size play a role in the time of performance. Higher resolution specific tile level -- up to ( default + 2 ) -- can be specified on experimental base, depending on the amount of data. If the value of the clusterning resolution exceeds the maximum value for tile level, the maximum resolution will be used instead.

Zoomlevel Default H3 Resolution
0 2
1 2
2 2
3 2
4 3
5 4
6 4
7 5
8 6
9 6
10 7
11 8
12 9
13 9
14 10
15 11
16 11
17 12
18 13
19 13
20 13
21 13
22 13

Quadbin

Fire data
Figure 2. Fire data

The quadbin algorithm takes the geometry input of the request (e.g. quadkey / bbox..) and does estimated count on the features contained in the layer. This clustering mode works also for very large layers and can be used for getting an overview where data is geolocated in a given layer. Furthermore, a property filter on one property is applicable.

There are several parameters needed by the quadbin algorithm. You can use one property filter in combination.

Request

GET /<Base path for the interactive API from the API Lookup Service>/layers/<Layer ID>/tile/<Tile Type>/<Tile ID>?clustering=quadbin&clustering.relativeResolution=<#number>&clustering.countmode=<cmode>

The following clustering related parameters can be passed

Parameter Type Mandatory Meaning
relativeResolution Number No Integer, the quad resolution [0,4]
noBuffer Boolean No Do not place a buffer around quad polygons, default: false
countmode String No [real, estimated, mixed]

real = real feature counts
Best accuracy, but slow.
Not recommended for big result sets

estimated = estimated feature counts
Low accuracy, but very fast
Recommended for big result sets

mixed (default) = estimated feature counts combined with real ones
If the estimation is low a real count gets applied.
Fits most use cases

Response

{
    "type": "FeatureCollection",
    "features": [
        {
            "type": "Feature",
            "properties": {
                "qk": "12002323333",     // tile quadkey
                "xyz": "(639,1071,11)",  // tile row/col/level 
                "count": 30393,          // count of features in tile 
                "estimated": true,       
                "total_count": 33521484,      // total feature count in related layer
                "equipartition_count": 511    // total_count/#Nr_Of_All_Level_Tiles
            },
            "geometry": {...}  
        },
        ......
        ......
        {
            "type": "Feature",
            "type": "Feature",
            "properties": {
                "qk": "12002323331",
                "xyz": "(638,1071,11)", 
                    ....
            },
            "geometry": {...}
        }
    ]
}

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