CoverageJSON output format¶
CoverageJSON is a format for encoding geotemporal coverage data like grids and time series. For example, it can be as output format for a WCS2.0 getCoverage requesting a TimeSeries on a specific coordinate. As per the specification, the format to be specified to get back a cov-json output is application/prs.coverage+json.
Installation¶
As a community module, the cov-json package needs to be downloaded from the nightly builds,
picking the community folder of the corresponding GeoServer series (e.g. if working on the GeoServer main development branch nightly
builds, pick the zip file form master/community-latest).
To install the module, unpack the zip file contents into GeoServer own WEB-INF/lib directory and restart GeoServer.
Example: WCS 2.0 - TimeSeries¶
Let test:timeseries be a sample layer related to a coverage with time dimensions enabled. Suppose we want to get the coverage values for a specific time period on a specific lat/lon coordinate. That will be a slicing on lat/lon coordinate and trimming on time dimension.
A getCoverage request can be posted with a similar content to http://server:port/geoserver/wcs:
<wcs:GetCoverage service="WCS" version="2.0.1"
xmlns:wcs="http://www.opengis.net/wcs/2.0"
xmlns:gml="http://www.opengis.net/gml/3.2"
xmlns:crs="http://www.opengis.net/spec/WCS_service-extension_crs/1.0"
xmlns:rsub="http://www.opengis.net/spec/wcs_service-extension_range-subsetting/1.0"
xmlns:scal="http://www.opengis.net/spec/WCS_service-extension_scaling/1.0/"
xmlns:wcsgeotiff="http://www.opengis.net/wcs/geotiff/1.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.opengis.net/wcs/2.0 http://schemas.opengis.net/wcs/2.0/wcsAll.xsd">
<wcs:CoverageId>test__timeseries</wcs:CoverageId>
<wcs:format>application/prs.coverage+json</wcs:format>
<wcs:DimensionSlice>
<wcs:Dimension>Long</wcs:Dimension>
<wcs:SlicePoint>56</wcs:SlicePoint>
</wcs:DimensionSlice>
<wcs:DimensionSlice>
<wcs:Dimension>Lat</wcs:Dimension>
<wcs:SlicePoint>0</wcs:SlicePoint>
</wcs:DimensionSlice>
<wcs:DimensionTrim>
<wcs:Dimension>Time</wcs:Dimension>
<wcs:TrimLow>2014-01-01T00:00:00.000Z</wcs:TrimLow>
<wcs:TrimHigh>2017-01-01T00:00:00.000Z</wcs:TrimHigh>
</wcs:DimensionTrim>
</wcs:GetCoverage>
The outcome will be something like this:
{
"type": "Coverage",
"domain": {
"type": "Domain",
"domainType": "PointSeries",
"axes": {
"x": {
"values": [
56.0
]
},
"y": {
"values": [
1.0112359550561785
]
},
"t": {
"values": [
"2014-01-01T00:00:00Z",
"2015-01-01T00:00:00Z",
"2016-01-01T00:00:00Z",
"2017-01-01T00:00:00Z"
]
}
},
"referencing": [
{
"coordinates": [
"x",
"y"
],
"system": {
"type": "GeographicCRS",
"id": "http://www.opengis.net/def/crs/EPSG/0/4326"
}
},
{
"coordinates": [
"t"
],
"system": {
"type": "TemporalRS",
"calendar": "Gregorian"
}
}
]
},
"parameters": {
"TIMESERIES": {
"type": "Parameter",
"description": {
"en": "timeseries"
},
"observedProperty": {
"label": {
"en": "timeseries"
}
}
}
},
"ranges": {
"TIMESERIES": {
"type": "NdArray",
"dataType": "float",
"axisNames": [
"t",
"y",
"x"
],
"shape": [
4,
1,
1
],
"values": [
25.5,
24.76,
26.06,
23.22
]
}
}
}
Note the domainType = PointSeries where x,y axes have a single and the t axis has 4 times in the values. Also note the ranges property is reporting 4 values.