As everyone who is involved in teaching and training knows, the past few months have been hard. We all had to make changes to accommodate working from home and adopting online teaching methods. Before the COVID-19 outbreak, I used to conduct all my training in-person. Either hosting it at a training center or at a client location. My materials, structure and instruction style was tuned to this setup. I was skeptical whether the experience of a classroom can be replicated – even partially – online.

Over the past 2 months, I have conducted numerous online training sessions. All my courses have been moved to a ‘live’ online class and even started offering short-format classes. I did a lot of research, talked to other trainers and spent a considerable effort in trying to make this transition. I thought sharing some of the lessons and best practices here will help fellow educators.

Continue reading

I was invited to participate in a panel discussion on Geospatial Intelligence for #LetsTalkDeepTech Webcast hosted by Swiggy. I talked about the history and evolution of this space and gave a deep dive into solutions for deriving intelligence from imagery.

Below is the a longer version of my talk on evolution of location intelligence with some references. I also share a copy of my presentation at the end. Hope you find it useful. Agree/Disagree with my views? Let me know in the comments.

Continue reading

Time series analysis is one of the most common operations in Remote Sensing. It helps understanding and modeling of seasonal patterns as well as monitoring of land cover changes. Earth Engine is uniquely suited to allow extraction of dense time series over long periods of time.

In this post, I will go through different methods and approaches for time series extraction. While there are plenty of examples available that show how to extract a time series for a single location – there are unique challenges that come up when you need a time series for many locations spanning a large area. I will explain those challenges and present code samples to solve them.

The ultimate goal for this exercise is to extract NDVI time series from Sentinel-2 data over 1 year for 100 farm locations spanning an entire state in India.

Continue reading

In a previous post, I showed how to use the aggregate function to find neighbor polygons using QGIS. Using aggregate functions on the same layer allows us to easily do geoprocessing operations between features of a layer. This is very useful in many analysis that would typically require writing custom python scripts.

Here I demonstrate another powerful function array_foreach that allows one to iterate over other features in QGIS expressions – enabling even more powerful analysis by writing just a single expression.

Continue reading

Google Earth Engine (GEE) is a powerful cloud-based system for analysing massive amounts of remote sensing data. One area where Google Earth Engine shines is the ability to calculate time series of values extracted from a deep stack of imagery. While GEE is great at crunching numbers, it has limited cartographic capabilities. That’s where QGIS comes in. Using the Google Earth Engine Plugin for QGIS and Python, you can combine the computing power of GEE with the cartographic capabilities of QGIS. In this post, I will show how to write PyQGIS code to programmatically fetch time-series data, and render a map template to create an animated maps like below.

Continue reading