NGSI: Geoqueries & Carto integration
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The document outlines the geospatial features of the Orion Context Broker and the integration with the Cygnus tool and Carto for data persistence related to geo-located entities. It describes various methods to define entity locations (points, lines, boxes, and polygons) and discusses the ability to execute geospatial queries based on spatial relationships. Additionally, it details the persistence types in Cygnus and provides examples of querying geo-located entities in Malaga, highlighting both basic and advanced demo scripts.
![Geo-locating an entity
2
Point location
POST /v2/entities
{
"id": "E",
"type": "T",
"location": {
"type": "geo:json",
"value": {
"type": "Polygon",
"coordinates": [ [ [2, 1], [4, 3], [5, -1], [2, 1] ] ]
} } }
POST /v2/entities
{
"id": "E",
"type": "T",
"location": {
"type": "geo:polygon",
"value": [ "2, 2", "8, 7", "-1, 4", "2, 2"]
}
}
POST /v2/entities
{
"id": "E",
"type": "T",
"location": {
"type": "geo:box",
"value": [ "2, 2", "8, 7" ]
}
}
POST /v2/entities
{
"id": "E",
"type": "T",
"location": {
"type": "geo:point",
"value": "40.41,-3.69"
}
}
POST /v2/entities
{
"id": "E",
"type": "T",
"location": {
"type": "geo:line",
"value": [ "2, 2", "8, 7" ]
}
}
Line location
(e.g. a street)
Box location
(e.g. a squared building)
Polygon location
(e.g. a city district)
GeoJSON geometry (full flexibility)](https://image.slidesharecdn.com/ngsigeoqueriesandcartointegration-161229175613/85/NGSI-Geoqueries-Carto-integration-3-320.jpg)
NGSI: Geoqueries & Carto integration
- 1. NGSI: geoqueries and Carto integration Fermín Galán Márquez, Francisco Romero Bueno Data Chapter Team fermin.galanmarquez@telefonica.com, francisco.romerobueno@telefonica.com
- 2. Geospatial features 1 • Orion Context Broker geospatial features • Entities may have a location • Queries/subscriptions may use the location as search criteria • Historical context persistence geospatial features • Entities location is progressed to geo-enabled persistence backends through Cygnus tool • Carto is the main persistence backend used by Cygnus when dealing with geo-located entities • Cloud-based service • Visualizations, analysis and widgets can be added to maps
- 3. Geo-locating an entity 2 Point location POST /v2/entities { "id": "E", "type": "T", "location": { "type": "geo:json", "value": { "type": "Polygon", "coordinates": [ [ [2, 1], [4, 3], [5, -1], [2, 1] ] ] } } } POST /v2/entities { "id": "E", "type": "T", "location": { "type": "geo:polygon", "value": [ "2, 2", "8, 7", "-1, 4", "2, 2"] } } POST /v2/entities { "id": "E", "type": "T", "location": { "type": "geo:box", "value": [ "2, 2", "8, 7" ] } } POST /v2/entities { "id": "E", "type": "T", "location": { "type": "geo:point", "value": "40.41,-3.69" } } POST /v2/entities { "id": "E", "type": "T", "location": { "type": "geo:line", "value": [ "2, 2", "8, 7" ] } } Line location (e.g. a street) Box location (e.g. a squared building) Polygon location (e.g. a city district) GeoJSON geometry (full flexibility)
- 4. Important remark regarding coords order 3 POST /v2/entities { "id": "E", "type": "T", "location": { "type": "geo:point", "value": "40.41,-3.69" } } POST /v2/entities { "id": "E", "type": "T", "location": { "type": "geo:json", "value": { "type": "Point“, "value": "-3.69, 40.41" } } same location geo:json uses long-lat, while other formas use lat-long Cygnus is able to swap coordinates when persisting data!
- 5. Geospatial queries at Context Broker 4 • They can be used both in synchronous (GET /v2/entities) and asynchronous (subscriptions) queries • Queries are based on a spatial relationship and a geometry • Spatial relationships: • near (max and min distance) • coveredBy • intersects • equal • disjoint • Geometries • point • line • box • polygon
- 6. Persistence of geo-locates entities in Carto through Cygnus 5 • Cygnus is able to create 3 (4) kind of persistence: • Raw historic • A table is created for each entity. It contains the history regarding the position (and any other attribute) of the entity • Raw snapshot • A single table handles the last position (ant the last value of any other attribute) of the entity • Distance historic • A table is created for each entity. It contains already processed distance-based analytics • Total distance and time • Last stage distance, time and speed • Maximum and minimum distance, time and speed • Average distance, time and speed, and variance • (Distance snapshot - roadmap)
- 7. Demo setup 6 Orion Context Broker @ FIWARE Lab NGSIv2 API context information: Malaga buses & streets Cygnus (using Carto connector) @ FIWARE Lab carto.com geo-located collections notifications callstoCartoAPI Carto API & dashboard Service: sc_malaga Subservice: /roads
- 8. 7 Demo time!
- 10. Demo 1 (basic queries) script 9 • Prep: • Run the script to update bus lines each 5s • Steps • Show Malaga maps with the bus moving around the city • Do a ?type=bus query, then pick an specific bus and do several queries to see how location is shown and how it changes from time to time • Stop the script in a moment in which some buses are inside and some outside the center district. Now the buses got halted on the web page • Pick a point and do near-to queries in progressive distance, to see how more buses get grabbed • Do a polygon query for center district
- 11. Demo 2 (advanced queries) script 10 • Pre • Use https://drive.google.com/open?id=1jr5qnBQVTfXnD2EBG_ _XR2Vk-dc&usp=sharing • Scripts: • https://gist.github.com/fgalan/2143bff997ed039555ae8d0e afaa6b5f • Steps • Do a ?type=street query and show how location is modeled in some of them • Query 1: streets close to a given point (e.g. bus stop), 10 meters to 150 m • Query 2: streets that cross a given street • Query 3: streets that don't cross a given street • Query 4: streets fully inside Malaga center district • Query 5: streets partially inside Malaga center district • Query 5: streets outside Malaga center district