An important concept in spatial statistics is pixel weights. When calculating pixel statistics with a polygon, partial pixel overlaps are treated differently by different packages and you need to understand …

Modern versions of QGIS comes with a handy command-line utility called qgis_process. This allows you to access and run any Processing Tool, Script or Model from the Processing Toolbox on …

In this post, I describe how we can use built-in QGIS processing tools to create a workflow to split polygons into equal parts. Using a clever algorithm and Feature Iterator …

In this post, I will outline techniques for computing weighted-centroids in both QGIS and Google Earth Engine. For a polygon feature, the centroid is the geometric center. It can also …

I recently taught a 1-month long course on GIS Applications in Urban and Regional Planning. We explored how GIS can be applied to solve problems in 6 different thematic areas. …

Rainfall is arguably the most frequently measured hydro-meteorological variable. It is a required input for many hydrological applications like runoff computations, flood forecasting as well as engineering design of structures. …

When working with raster data, you may sometimes need to deal with data gaps. These could be the result of sensor malfunction, processing errors or data corruption. Below is an …

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 …

Generating pseudo-random data is important for many aspects of research work. QGIS provides for many methods of generating random points to facilitate this. Recently, I ran into a problem where …

Table Joins are a way to join 2 separate layers based on a common attribute value. QGIS has a Join Attributes By Field Value algorithm that allows you to table …

Read my previous posts Summary Aggregate and Spatial Filters and Advanced Aggregate Expressions to Automate QA to learn more about the powerful aggregate function. The aggregate function in QGIS was …

This post is the continuation of Summary Aggregate and Spatial Filters in QGIS. I have been exploring aggregate functions more and have found interesting ways to automate tasks in QGIS. …

QGIS expression engine has a powerful a summary aggregate function that can do spatial joins on the fly. This enables some very interesting uses. One such use is to enable …

You may have seen a map where source and destination points are connected via curved lines. It is possible to create such a map in QGIS with a simple trick …

QGIS expression engine has a powerful a summary aggregate function that can do spatial joins on the fly. This enables some very interesting uses. One such use is to enable …

This post is the continuation of Summary Aggregate and Spatial Filters in QGIS. I have been exploring aggregate functions more and have found interesting ways to automate tasks in QGIS. …

Read my previous posts Summary Aggregate and Spatial Filters and Advanced Aggregate Expressions to Automate QA to learn more about the powerful aggregate function. The aggregate function in QGIS was …

Table Joins are a way to join 2 separate layers based on a common attribute value. QGIS has a Join Attributes By Field Value algorithm that allows you to table …

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 …

Rainfall is arguably the most frequently measured hydro-meteorological variable. It is a required input for many hydrological applications like runoff computations, flood forecasting as well as engineering design of structures. …

When you want to buffer features that are spread across a large area (such as global layers), there is no suitable projection that can give you accurate results. This is …

When trying to automate your GIS workflows, one important step is the production of maps. Creating and exporting maps in QGIS is done via the Print Layout. One can automate …

If you have collected GPS tracks, you know that the results can have varying accuracy. The track points collected along a route are not always on the road and can …

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 …

K-Means Clustering is a popular algorithm for automatically grouping points into natural clusters. QGIS comes with a Processing Toolbox algorithm 'K-means clustering' that can take a vector layer and group …

Dynamic World is a new landcover product developed by Google and World Resources Institute (WRI). It is a unique dataset that is designed to make it easy for users to …

Extracting building footprints from high-resolution imagery is a challenging task. Fortunately we now have access to ready-to-use building footprints dataset extracted using state-of-the-art ML techniques. Google's Open Buildings project has …

An important concept in spatial statistics is pixel weights. When calculating pixel statistics with a polygon, partial pixel overlaps are treated differently by different packages and you need to understand …

In this article, I will outline a method for extracting shoreline from satellite images in Google Earth Engine. This method is scalable and automatically extracts the coastline as a vector …

If you are like me, you have a lot of assets uploaded to Earth Engine. As you upload more and more assets, managing this data becomes quite a cumbersome task. …

Many applications require replacing missing pixels in an image with an interpolated value from its temporal neighbours. This gap-filling technique is used in several applications, including: Replacing Cloudy Pixels: You …

Most optical satellite imagery products come with one or more QA-bands that allows the user to assess quality of each pixel and extract pixels that meet their requirements. The most …

In this post, I will outline techniques for computing weighted-centroids in both QGIS and Google Earth Engine. For a polygon feature, the centroid is the geometric center. It can also …

Google Earth Engine makes it easy to compute statistics on gridded raster datasets. While calculating statistics on imagery datasets is easy, special care must be taken when working with population …

Many useful climate and weather datasets come as gridded rasters. The techniques for working with them is slightly different than other remote sensing datasets. In this post, I will show …

Color correction is an important process working with satellite and aerial imagery. A common technique used to balance the colors across multiple images is Histogram Matching. While the algorithm has …

When working on Remote Sensing applications, many operations require calculating area. For example, one needs to calculate area covered by each class after supervised classification or find out how much …

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 …

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 …

An important concept in spatial statistics is pixel weights. When calculating pixel statistics with a polygon, partial pixel overlaps are treated differently by different packages and you need to understand …

Matplotlib has functionality to created animations and can be used to create dynamic visualizations. In this post, I will explain the concepts and techniques for creating animated charts using Python …

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. QGIS as well as …

When working with raster data, you may sometimes need to deal with data gaps. These could be the result of sensor malfunction, processing errors or data corruption. Below is an …

Multi-criteria Overlay Analysis is the process of the allocation of land to suit a specific objective on the basis of a variety of attributes that the selected areas should possess. …

When working with raster data, you may sometimes need to deal with data gaps. These could be the result of sensor malfunction, processing errors or data corruption. Below is an …

gdal_calc is one of the lesser used tools among the GDAL utilities. There aren't many examples of using it in the wild and some advanced features are not well documented. …

When working with elevation data, sometimes you may discover that 2 datasets from different providers have very different elevation values for the same location. A common reason for this being …

GeoPDF is a unique data format that brings the portability of PDF to geospatial data. A GeoPDF document can present raster and vector data and preserve the georeference information. This can …

GDAL and OGR libraries come with handy command-line tools. These tools are quite powerful and can save you a lot of effort if you know how to use them. Here I …

In a previous post, I showed how to use the Uber Movement Travel Times data to create isochrones. In this post, we will explore another use case of this dataset. …

Mapshaper is a free and open-source software for spatial data processing. It is written in javascript and runs in your browser without any extra plugins and can perform a range …

Mapshaper is a free and open-source tool that is best known for fast and easy simplification. Other tools for simplification – like QGIS or ogr2ogr – do not preserve topology while …

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 …

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 …

Converting between different coordinate reference systems or projection is a fairly standard feature in a GIS. There are a number of command line tools also available for performing bulk-conversions. cs2cs program, part …

This weekend, I got an opportunity to volunteer with a non-profit called Junglescapes. We took a day trip to the Bandipur forest in Karnataka where they have done extensive work in …

The Association for People with Disability (APD) is a non-profit organization based out of Bangalore, India. Their mission is to reach out and rehabilitate people with disability from the under privileged segment. …

A long pending weekend project is done. Printed, cut and folded a sturdy globe using the template from Le Paper Globe. This is not only fun, but a good prop to …

I recently had a need to calculate distance between a large number of latitude/longitude coordinate pairs. There are many options available if you want to import these in a GIS …

Many students have asked me for ideas on what topic they should choose for their Thesis. I have debated this myself when I was a student. The ideal topic would …