Tools to communicate, visualize, and quantify change over time
By Allie Lieber, Program Manager and Nicholas Clinton, Developer Advocate, Google Earth Outreach and Earth Engine
As India’s environmental and cultural landscape is rapidly changing, nonprofit organizations across India are using the latest technology to raise awareness about key issues, and share the benefits of development across society. Sometimes it can be difficult to comprehend and communicate, let alone measure, these changes. At the recent Geo for Good India Summit the Google Earth Outreach team trained nonprofits and scientists on tools they can leverage to help people understand the scale of change that is taking place around them, like the Nature Conservation Foundation of India using Earth Engine to track current changes in forest cover and by the India Literacy Project using Google Earth to teach students about the past.
At the Geo for Good India Summit, we had several Google Earth Engine training sessions. Earth Engine combines a multi-petabyte catalog of satellite imagery and geospatial datasets with a simple, yet powerful API backed by Google’s cloud, which scientists and researchers use to detect, measure, and predict changes to the Earth’s surface.
I spent 4 days at the Summit with 80 participants from nonprofits around India. One of the participants Bhawna Sharma, a GIS Specialist at The Nature Conservancy’s India Program, was interested in visualizing lakes and wetlands, like the Pallikaranai Marshland in Chennai, which is shrinking due to unplanned rapid urbanization in the last two decades. The first thing we tried was visiting the marshland in Google’s Earth Timelapse — which is a global, zoomable video of the entire planet since 1984 — an amazing visualization of change over time, globally.
In Sharma’s area of interest, the visualization in Earth Timelapse was not ideal, as clouds and other artifacts obscured some of the key parts of the marshland. Luckily, Nicholas Clinton, our Developer Advocate was with us in Bangalore and helped us use Earth Engine to create our own animation of the Pallikaranai Marshland. Depending on the phenomenon you’re analyzing, you may want to go beyond the global Timelapse visualization, something Earth Engine is uniquely well-suited to help you do.
Using Earth Engine, it only took a few lines of code for us to get a custom Timelapse-like video that worked for Sharma’s specific analysis. To visualize Pallikaranai Marshland, which is pretty consistently covered by clouds, Nick recommended using 5 year time steps (rather than the 1-year step used for Earth Timelapse) in order to get a clearer composite. That is, with more images, you are more likely to have cloud-free pixels to use in your animation!
You can see this illustrated in the two sets of images above. The top set shows each of the 5-year images we created for Sharma’s analysis. The animated set below shows the equivalent frames from the Earth Timelapse animation.
At the summit, Sharma learned how to go from the above Timelapse video above to the cleaner, cloud-free video below:
Powerful visuals such as these can be extremely useful in conveying important messages to all stakeholders efficiently– in this case, it was to draw attention towards encroachment and shrinking of a marshland.
If you would like to make your own time-based animations using Earth Engine, take a look at the code used to generate the video. (You may need to sign up with Earth Engine to see it!) Other types of visualizations are also possible with Earth Engine. For example, you can tweak the code to visualize changes in NDVI, or other indices, overtime.
For nonprofits looking to learn more about the program, see Google Earth Outreach and Google for Nonprofits websites. We’d love to get in touch. Share your stories with us at geoforgood-india@google.com and stay up-to-date by joining our mailing list.
