CouchDB Day NYC 2017: Using Geospatial Data in Cloudant & CouchDB
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Since GeoJSON is a standard for storing geographic data in JSON format, it is a best practice to adhere to this format when storing geo-coordinates in Cloudant and CouchDB.
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CouchDB Day NYC 2017: Using Geospatial Data in Cloudant & CouchDB
- 1. @rajrsingh Watson Data Platform Using Geospatial Data in Cloudant & CouchDB February, 2017
- 2. @rajrsingh Watson Data Platform Why Geospatial? • Humans are wired by evolution to think spatially • Location tells you a lot about your data • Design with Nature (1969) pioneered the concept of ecological planning. Ian McHarg sets forth the basic concepts that were to develop later into geographic information systems. Courtesy Wikipedia
- 3. @rajrsingh Watson Data Platform Faking Geo with CouchDB • Secondary index on X and Y • Mango query X and Y • Pull data to the client, then… • Use PouchDB + https://github.com/pouchdb/geopouch for bounding box queries or • http://turfjs.org for more complete geospatial analysis
- 4. @rajrsingh Watson Data Platform Components of a great mobile mapping app © Copyright IBM Corporation 2015 Basemap tiles: Mapbox API Query: all restaurants X meters from Y that serve Z Web client: MapboxGL Custom data: restaurants
- 5. @rajrsingh Watson Data Platform Going Beyond the Bounding Box
- 7. @rajrsingh Watson Data Platform GeoJSON Data Format – geometry property • required: type property with a value such as Point, LineString or Polygon • required: coordinates property – properties property • all the other data • optional in Cloudant/CouchDB – type property set to Feature – http://geojson.org
- 8. @rajrsingh Watson Data Platform Geo Queries – base URL /<db>/_design/<ddocname>/_geo/<geoindexname>? – bounding box bbox=minlon,minlat,maxlon,maxlat – radius lat=39.96&lon=-75.15&radius=300&relation=contains polygon relation=overlaps &g=POLYGON ((-71.0537124 42.3681995,-71.054399 42.3675178,- 71.0522962 42.3667409,-71.051631 42.3659324,-71.051631 42.3621431,-71.0502148 42.3618577,-71.0505152 42.3660275,- 71.0511589 42.3670263,-71.0537124 42.3681995))
- 9. @rajrsingh Watson Data Platform Spatial Relationship Types BBox Contains Crosses Disjoint Equals Intersects Overlaps Touches Within
- 13. @rajrsingh Watson Data Platform Resources • Location Tracker tutorials • https://developer.ibm.com/clouddataservices/location-tracker/ • Cloudant Geo • Marketing overview https://www.ibm.com/analytics/us/en/technology/location-based- apps/ • Technical docs https://docs.cloudant.com/geo.html • Me • Twitter @rajrsingh • Email rrsingh@us.ibm.com
Notes de l'éditeur
- Humans are wired to think spatially Go out to hunt, track prey and return home safely Nomadic tribes, migration Location tells you a lot about a user At home or work What are they near? General demographics
- Want to pull in demographic profies and give you all the schema flexbility. Today you’ll see the skeleton of a mobile app, you can use the flexible schema will let you scale without worrying
- You can perform bounding box queries that return local results, but they may not be all that compelling because a simple rectangle may cross impassable barriers such as highways or rivers.
- Multipoint polygons deliver better results for users. Here you see that the results are limited to a Lower East Side neighborhood in Manhattan.
- Since GeoJSON is a standard for storing geographic data in JSON format, it is a best practice to adhere to this format when storing geo-coordinates in Cloudant. GeoJSON format consists of three parts: The geometry section contains two fields: the coordinates and the type, such as Point, LineString, or Polygon. The properties section contains other optional data. And the type section must be set to “Feature”. The coordinates must adhere to the GeoJSON standard, but the properties object and type field are not required. GeoJSON assumes that coordinates are stored as follows in 4D scenarios: (x-axis, y-axis, z-axis, temporal) which equates to (longitude, latitude, height, temporal). Keep it in mind as most people think in terms of latitude, longitude order rather than longitude, latitude. For details on the accuracy and precision of coordinate data, refer to the Geographic Information Systems page on StackExchange. http://gis.stackexchange.com/questions/8650/how-to-measure-the-accuracy-of-latitude-and-longitude/8674#8674
- Since GeoJSON is a standard for storing geographic data in JSON format, it is a best practice to adhere to this format when storing geo-coordinates in Cloudant. GeoJSON format consists of three parts: The geometry section contains two fields: the coordinates and the type, such as Point, LineString, or Polygon. The properties section contains other optional data. And the type section must be set to “Feature”. The coordinates must adhere to the GeoJSON standard, but the properties object and type field are not required. GeoJSON assumes that coordinates are stored as follows in 4D scenarios: (x-axis, y-axis, z-axis, temporal) which equates to (longitude, latitude, height, temporal). Keep it in mind as most people think in terms of latitude, longitude order rather than longitude, latitude. For details on the accuracy and precision of coordinate data, refer to the Geographic Information Systems page on StackExchange. http://gis.stackexchange.com/questions/8650/how-to-measure-the-accuracy-of-latitude-and-longitude/8674#8674
- In Cloudant, geospatial relations are specified by the relation query parameter. Cloudant Geo supports the following standard geospatial relations: Bbox Contains Crosses Disjoint Equals Intersects Overlaps Touches Within Refer to the Geospatial Relationships section of the documentation for complete details on each of these relations.