Greyhound¶
Exercise¶
This exercise uses PDAL to fetch data from a Greyhound server. Greyhound is a web server for point cloud data. You can learn more about what it is by visiting http://lidarnews.com/articles/open-source-point-cloud-web-services-with-greyhound/
See the Dublin data used in this example in your browser at
http://potree.entwine.io/data/dublin.html
In your OSGeo4W Shell, navigate to the
C:\Users\hobu\PDAL\exercises\translation
folder.cd C:\Users\hobu\PDAL\exercises\translation
View the
greyhound.json
file in your editor. If the file does not exist, create it and paste the following JSON into it:{ "pipeline": [ { "type": "readers.greyhound", "url":"data.greyhound.io", "depth_begin":0, "depth_end":11, "resource":"dublin", "filter":{ "Classification": 2 } }, { "type": "writers.las", "compression": "true", "minor_version": "2", "dataformat_id": "0", "filename":"just-ground.laz" } ] }
Note
If you use the Developer Console when visiting http://speck.ly or http://potree.entwine.io, you can see the browser making requests against the Greyhound server at http://data.greyhound.io
Issue the following command in your OSGeo4W Shell.
Verify that the data look ok:
Visualize the data in http://plas.io
Notes¶
- readers.greyhound contains more detailed documentation about how to use PDAL’s Greyhound reader .
- As
depth_end
gets larger, the number of possible points goes up by nearly a factor of 4. Use thebounds
option of the reader to split up the boxes you are querying to decrease the potential number of points a query might return.