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Thanks for reading my newsletter. Special shoutout to the new subscribers! Read on for new learning resources and updates from the world of free and open-source geospatial tech.

Featured Topic: Spatial Indexing Techniques

 
Spatial indexing methods help speed up spatial queries. Most GIS software and databases provide a mechanism to compute and use spatial index for your data layers. 

University of Helsinki’s AutoGIS course has a thorough introduction to spatial indexing using R-Tree data structure which is used by QGIS, PostGIS, GeoPandas and many more. Mapbox blog has a visual deep dive into spatial search algorithms that explains the concepts quite well.
 
QGIS: You can read this new module of my Advanced QGIS course material, where I show how to build and use spatial index in QGIS which helps run your queries much faster.
Python: Geooff Boeing has a great article that explains the background and techniques for using R-Tree spatial index in Python. Zendrive - a ride-sharing analytics company - recently shared a blog post with details on how leveraging R-Tree helped them to scale up their analytics.

An alternative to R-Tree are grid-based indexing schemes - which are used by Google, Uber and many companies that deal with big datasets. I wrote a new blog post exploring Uber's H3 Hexagonal Spatial Index - which gives a big performance boost to certain types of analysis compared to R-Tree. 
Spatial Indexing with Uber's H3 Hexagonal Spatial Index

Learning Resources and News

 

QGIS

  • QGIS Swiss User Group had their meeting streamed online and all the presentations are now available online. I watched the livestream and enjoyed the presentations.
    • The big news has been native vector tile support in QGIS and there were 2 talks on that topic. 
    • Oslandia has developed several plugins for geological applications - particularly QGeologIS which allows visualization of drill holes in QGIS
    • Klas Karlsson's talk on QGIS symbology is a light hearted and hilarious exploration of QGIS symbology.
  • FOSS4G UK 2020 was also streamed online featuring a variety of talks related to open-source geospatial technologies. The talk description and videos are available on OsGeoUK website. I could attend a few of these talks live and here are some recommendations that you may want to check out. 
  • One of the most frequently questions I get is on using WMS data offline. OpenGIS.ch did a thorough investigation into techniques for downloading WMS data that is quite useful.
  • Kurt Menke has put out the complete video of his Data Visualization with QGIS workshop online. I attended his workshop last year and learnt a lot of cartography tricks that I use regularly. Highly recommended!.

Earth Engine 

Python



The math behind spherical and ellipsoidal geometric computations has always fascinated me. Bojan Šavrič shared his recent paper on area and volume computations on ellipsoidal surfaces which goes into depth and compares various approaches. General

You can browse, search and filter current and past learning resources in this public spreadsheet.

Upcoming Events


Talks


I am thrilled to be presenting 2 talks about QGIS Processing Toolbox and Advanced QGIS Expressions at QGIS North America 2020 Conference on 17/24/31 July, 2020. The event will be streamed live and registration is free.
 

Classes

 

I am grateful for the huge interest in my live online classes. There has been unanimous positive feedback about the learning experience in small groups of participants from diverse backgrounds.

In particular, my intro programming course Python Foundation for Spatial Analysis has been received quite well. It has been amazing to see participants who have never coded before solve their complex spatial analysis problems with just 8-hours of instruction followed by 1-1 mentoring. Check out some project submissions: unsupervised clustering and zonal statistics from sentinel-2 imagery.

Classes for the next month are currently sold out, but I am working on offering more classes. You may register for the waiting list to be the first one to know when new classes are scheduled.
I am always happy to hear from you, so feel free to just hit 'reply' and introduce yourself. Tell me what topics related to geospatial technology you are interested in. If you are a job-seeker, share your profile and I may be able to connect you with potential employers.

Regards, and Stay safe!
-Ujaval
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