[Notebooks](../) - [Access to Geospatial data](../Access to Geospatial data)

This notebook is heavly based on the Python GDAL/OGR Cookbook

In this first example we'll learn how to generate a proper OGR geometry of type "Geometry Collection" which allow us to store multiple types of geometry (point, line, polygon) in a single vector file (note: this is a great advantage compared with the "standard but obsolete" ESRI Shape File data format, which is limited to only one type of geometry).

Let's re-use the example from the notebook in Numerical Cartograph/The Geodesic Problem, where using geograhiclib we compute the shortest path (geodesic) from New York, (NY) to Delhi, (India):



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from geographiclib.geodesic import Geodesic

lat1,lon1 = (40.7143528, -74.0059731)  # New York, NY
lat2,lon2 = (1.359, 103.989)   # Delhi, India
g = Geodesic.WGS84.Inverse(lat1, lon1, lat2, lon2)
g

Now compute a list of points along the geodesic curve with a fixed distance of 100000m



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gc = [Geodesic.WGS84.Direct(lat1, lon1, g['azi1'], i) for i in range(0,int(g['s12']),100000)]

Now let's start with OGR!

We will first create a geometry collection with:



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from osgeo import ogr
geomcol =  ogr.Geometry(ogr.wkbGeometryCollection)

let's add 2 point features for the 2 location we used to compute the geodesic curve:



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point1 = ogr.Geometry(ogr.wkbPoint)
point1.AddPoint(lon1,lat1)
geomcol.AddGeometry(point1)

point2 = ogr.Geometry(ogr.wkbPoint)
point2.AddPoint(lon2,lat2)
geomcol.AddGeometry(point2)

Let's add to our GeometryCollection a new line feature:



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line = ogr.Geometry(ogr.wkbLineString)

And let's populate the newly generated line feature looping trought the list of coordinates of our geodesic path.



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[line.AddPoint(i['lon2'],i['lat2']) for i in gc]
geomcol.AddGeometry(line)

And finally export the data as GeoJson string and paste it online for easy visualization ong github:



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data = geomcol.ExportToJson()

To save on file the new dataset we will echo the geojson string to a file and then use the gist utility to upload the data online:



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!echo '{data}' > /tmp/geojson.geojson



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!gist -p /tmp/geojson.geojson



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from CesiumWidget import CesiumWidget



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cesiumExample = CesiumWidget(width="100%",geojson=data, enable_lighting=True)



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cesiumExample