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https://github.com/IrishMarineInstitute/erddap-leaflet-velocity-demo
A demonstration of connecting Erddap to Leaflet Velocity maps
https://github.com/IrishMarineInstitute/erddap-leaflet-velocity-demo
current erddap leaflet leaflet-velocity meterology ocean oceanography velocity visualisation visualization water weather wind
Last synced: 3 months ago
JSON representation
A demonstration of connecting Erddap to Leaflet Velocity maps
- Host: GitHub
- URL: https://github.com/IrishMarineInstitute/erddap-leaflet-velocity-demo
- Owner: IrishMarineInstitute
- Created: 2020-12-14T13:12:50.000Z (over 3 years ago)
- Default Branch: main
- Last Pushed: 2022-05-18T06:39:02.000Z (about 2 years ago)
- Last Synced: 2024-01-23T03:22:38.549Z (5 months ago)
- Topics: current, erddap, leaflet, leaflet-velocity, meterology, ocean, oceanography, velocity, visualisation, visualization, water, weather, wind
- Language: JavaScript
- Homepage:
- Size: 187 KB
- Stars: 6
- Watchers: 5
- Forks: 4
- Open Issues: 3
-
Metadata Files:
- Readme: README.md
Lists
- awesome-erddap - erddap-leadlet-velocity-demo - A demonstration of connecting Erddap to [Leaflet-Velocity](https://github.com/danwild/leaflet-velocity) maps. (Web Mapping Services)
README
# erddap-leaflet-velocity-demo
A demonstration of connecting [Erddap](https://github.com) to [Leaflet-Velocity](https://github.com/danwild/leaflet-velocity) maps
See [here](https://irishmarineinstitute.github.io/erddap-leaflet-velocity-demo/) for an online demonstration.
See [here](https://irishmarineinstitute.github.io/erddap-leaflet-velocity-demo/time-dimension-example/) for example with time dimension control.
## Contents
- [Including the Code](https://github.com/IrishMarineInstitute/erddap-leaflet-velocity-demo/blob/main/README.md#including-the-code)
- [Example Usage](https://github.com/IrishMarineInstitute/erddap-leaflet-velocity-demo/blob/main/README.md#example-usage)
- [Function Inputs](https://github.com/IrishMarineInstitute/erddap-leaflet-velocity-demo/blob/main/README.md#function-inputs)
- [Grib2JSON Output format](https://github.com/IrishMarineInstitute/erddap-leaflet-velocity-demo/blob/main/README.md#grib2json-output-format)
- [JavaScript Boilerplate](https://github.com/IrishMarineInstitute/erddap-leaflet-velocity-demo/blob/main/README.md#javascript-boilerplate)
## Including the Code
To include the code in your own website, you will need to first add the [Leaflet.js](https://leafletjs.com/) mapping library, Leaflet-Velocity and then include errdapToLeafletVelocity, e.g.:
```html
```
## Example Usage
```javascript
L.erddapVelocityLayer({
erddapBaseUrl: 'https://erddap.marine.ie',
datasetID: 'IMI_Model_Stats',
uParameter: 'sea_surface_x_velocity',
vParameter: 'sea_surface_y_velocity',
minLat: 48.5,
maxLat: 58.5,
minLon: -17.0,
maxLon: -2.0,
refTime: '2019-12-15T00:00:00Z',
strideLon: 10,
strideLat: 10,
minVelocity: 0,
maxVelocity: 1}).addTo('map');
```
## Function Inputs
Once you have added the [erddapToLeafletVelocity.js](https://github.com/IrishMarineInstitute/erddap-leaflet-velocity-demo/blob/main/erddapToLeafletVelocity.js) script to your webpages, you can use the erddapToLeafletVelocity function or the L.erddapVelocityLayer function with the following inputs:
- _erddapBaseUrl_ `String`: The base URL of the Errdap server to be called - e.g. 'http://erddap.marine.ie'
- _datasetID_ `String`: The dataset name to be accessed from the Erddap server - 'e.g. IMI_Model_Stats'
- _uParameter_ `String`: The eastwards velocity parameter name to be accessed from the Erddap dataset - e.g. 'sea_surface_x_velocity'
- _vParameter_ `String`: The northwards velocity parameter name to be accessed from the Erddap dataset - e.g. 'sea_surface_x_velocity'
- _minLat_ `Number`: The southernmost latitude to be accessed from the Erddap dataset
- _maxLat_ `Number`: The northernmost latitude to be accessed from the Erddap dataset
- _minLon_ `Number`: The westernmost longitude to be accessed from the Erddap dataset
- _maxLon_ `Number`: The easternmost longitude to be accessed from the Erddap dataset
- _refTime_ `String`: The dateTime for the data to be returned from Erddap
- _strideLon_ `Number`: The Erddap stride to use on the grid for the longitude axis as an integer value
- _strideLat_ `Number`: The Erddap stride to use on the grid for the latitude axis as an integer value
- _minVelocity_ `Number`: The minimum velocity to use on the Leaflet Velocity display
- _maxVelocity_ `Number`: The maximum velocity to use on the Leaflet Velocity display
- _mapID_ `String`: The Leaflet map ID to add the velocity layer to
## Grib2JSON output format
Leaflet-Velocity expects input in the form of a JSON object conforming to the output of [Grib2JSON](https://github.com/cambecc/grib2json). Some of the fields are documented below:
- Header
- _dx_ The grid spacing on the x-axis in degrees
- _dy_ The grid spacing on the y-axis in degrees
- _la1_ The northernmost latitutde of the grid
- _la2_ The southernmost latittude of the grid
- _lo1_ The westernmost longitude of the grid
- _lo2_ The easternmost longitude of the grid
- _nx_ The number of grid points on the x axis
- _ny_ The number of grid points on the y-axis
- _parameterCategory_ Use the integer 2
- _parameterNumber_ Use the integer 2 for the x-axis speed and the integer 3 for the y axis speed
- _parameterNumberName_ A plain text label for the parameter
- _parameterUnit_ The units of measure for the parameter
- _refTime_ The date and time for this parameter and grid combination
- Data
- A one-dimensional array of the parameter's data values for this point in time on the grid. Data are west-to-east across the grid, repeating north-to-south down the grid
## JavaScript boilerplate
The following should allow you to build the expected output from any Erddap instance, using a griddap enabled dataset. Contains input from [@abkfenris](https://github.com/abkfenris).
```javascript
const erddapBaseUrl = 'https://erddap.marine.ie';
const datasetID = 'IMI_Model_Stats';
const uParameter = 'sea_surface_x_velocity';
const vParameter = 'sea_surface_y_velocity';
const minLat = 48.5;
const maxLat = 58.5;
const minLon = -17.0;
const maxLon = -2.0;
const refTime = '2019-12-15T00:00:00Z';
const strideLon = 20;
const strideLat = 20;
function jsonp(url) {
return new Promise(function(resolve, reject) {
let script = document.createElement('script')
const name = "_jsonp_" + Math.round(100000 * Math.random());
//url formatting
if (url.match(/\?/)) url += "&.jsonp="+name
else url += "?.jsonp="+name
script.src = url;
window[name] = function(data) {
resolve(data);
document.body.removeChild(script);
delete window[name];
}
document.body.appendChild(script);
});
}
jsonp(erddapBaseUrl
+ '/erddap/griddap/'
+ datasetID
+ '.json?'
+ uParameter + '[(' + refTime + '):1:(' + refTime + ')][(' + String(minLat) + '):' + String(strideLat) + ':(' + String(maxLat) + ')][(' + String(minLon) + '):'+ String(strideLon) +':(' + String(maxLon) + ')],'
+ vParameter + '[(' + refTime + '):1:(' + refTime + ')][(' + String(minLat) + '):' + String(strideLat)+ ':(' + String(maxLat) + ')][(' + String(minLon) + '):' + String(strideLon) + ':(' + String(maxLon) + ')]')
.then(
data => [{
'header':{
'la1': Math.max(...Array.from([...new Set(data.table.rows.map(x => x[1]))])),
'la2': Math.min(...Array.from([...new Set(data.table.rows.map(x => x[1]))])),
'lo1': Math.min(...Array.from([...new Set(data.table.rows.map(x => x[2]))])),
'lo2': Math.max(...Array.from([...new Set(data.table.rows.map(x => x[2]))])),
'dx': (Math.max(...Array.from([...new Set(data.table.rows.map(x => x[2]))])) - Math.min(...Array.from([...new Set(data.table.rows.map(x => x[2]))]))) / ([...new Set(data.table.rows.map(x => x[2]))].length - 1),
'dy': (Math.max(...Array.from([...new Set(data.table.rows.map(x => x[1]))])) - Math.min(...Array.from([...new Set(data.table.rows.map(x => x[1]))]))) / ([...new Set(data.table.rows.map(x => x[1]))].length - 1),
'nx': [...new Set(data.table.rows.map(x => x[2]))].length,
'ny': [...new Set(data.table.rows.map(x => x[1]))].length,
'parameterCategory': 2,
'parameterNumber': 2,
'parameterUnit': 'm.s-1',
'parameterNumberName': data.table.columnNames[3],
'refTime': refTime.replace('T', ' ').replace('Z','')
},
'data': data.table.rows.sort((a,b) => b[1]-a[1]).map(x => x[3])
},{
'header':{
'la1': Math.max(...Array.from([...new Set(data.table.rows.map(x => x[1]))])),
'la2': Math.min(...Array.from([...new Set(data.table.rows.map(x => x[1]))])),
'lo1': Math.min(...Array.from([...new Set(data.table.rows.map(x => x[2]))])),
'lo2': Math.max(...Array.from([...new Set(data.table.rows.map(x => x[2]))])),
'dx': (Math.max(...Array.from([...new Set(data.table.rows.map(x => x[2]))])) - Math.min(...Array.from([...new Set(data.table.rows.map(x => x[2]))]))) / ([...new Set(data.table.rows.map(x => x[2]))].length - 1),
'dy': (Math.max(...Array.from([...new Set(data.table.rows.map(x => x[1]))])) - Math.min(...Array.from([...new Set(data.table.rows.map(x => x[1]))]))) / ([...new Set(data.table.rows.map(x => x[1]))].length - 1),
'nx': [...new Set(data.table.rows.map(x => x[2]))].length,
'ny': [...new Set(data.table.rows.map(x => x[1]))].length,
'parameterCategory': 2,
'parameterNumber': 3,
'parameterUnit': 'm.s-1',
'parameterNumberName': data.table.columnNames[4],
'refTime': refTime.replace('T', ' ').replace('Z','')
},
'data': data.table.rows.sort((a,b) => b[1]-a[1]).map(x => x[4])
}]
)
```