Open Satellite Data for Nepal and Where to Find Them


Satellites are probably THE most important pieces of engineering that has made an enormous, enormous impact on how we perceive, move and use the spatial space around us. Whether you are checking the weather, using google maps to find that highly rated, road-side MoMo bistro or making that long distance phone call to your loved one, you are utilizing the sheer power of human engineered hardware orbiting in space. 

And with the now popular CubeSat platform going viral among universities and space startups around the globe, there are more hands-on, satellite system understood engineers than anytime in history of space engineering. One can only imagine how what sort mature missions are going to pop up in the next 50 years with such disposable human power and brains. Quite an age we are living in. 

What's even better is that data from some of the satellites are open. If you don't believe in free lunch then think again. That means countries with no space faring hardware of their own can utilize and be informed with the data that is available from the satellite. I was frankly surprised that many organizations in Nepal still are in the dark regarding availability of such data; data that could potentially benefit both for-profit and non-profit establishments. 

In order to be able to utilize the data, I assume you have basic knowledge on terminologies associated with remote sensing, multi-spectral imagery and basic know-how of indices to make practical use of raw information provided by these awesome web portals. If not, there's this thing called the internet and in it, you will most certainly find google to do some googly-stuff. 

Let's start out with where the money is

1) Remote Sensed Data for Disaster/During Disaster

Startup PlanetLabs uses constellation of 3U CubeSats to map earth daily at 3-5m GSD
Seen here is one of the data released for Nepal during earthquake
UN has created an exhaustive list on 2015's earthquake satellite image data (processed/ unprocessed) that can be downloaded [HERE]. Most of them are on United States Geological Survey (USGS) website for disaster [HERE]. These include very high, sub-meter resolution data from commercial satellites as well. During the earthquake, I had so happened to be taking an online course on disaster management using satellite technology and is documented [HERE], if that's your cup of super sweetened tea. You could also use such data to write journal papers as well. You can find mine [HERE] to predict, using simple NDVI, where landslide could hit next in an event of an earthquake.



2) USGS's Earth Explorer [HERE]



USGS has a ridiculous amount of data from LANDSAT series of satellite including legacy data that date backs to 40 years. That is a lot of data waiting to be analyzed. As the satellite visits the same area of Nepal about every week, there are about a 3-4 data products that can be downloaded for a month for a GSD of 30m (15m for panchromatic bands). As mentioned [HERE] in the website, USGS's Earth Explorer also provides access to NASA's ASTER and Shuttle Radar Topography Missions for Digital Elevation Models and also provides full access to NASA's products on Hyperion's hyper-spectral data, MODIS and AVHRR data. Time to start mining.

3) Sentinel Scientific Data Hub [HERE]

NDVI calculation shows areas of healthy, mature vegetation in red
I might be wrong because there's no legend for colors
Source: ESA

Having a 10m GSD resolution satellite data for RGB and Near IR band with a return satellite pass of every 3-4 days for absolutely free would have been a too good to be true prospect a decade or so ago.

Not now.

With the Sentinel-2a and 2b satellites, European Space Agency (ESA) is offering better spatial resolution with an improved temporal resolution than the LANDSAT data.  Additionally, with the Sentinel-1 C-band Synthetic Apeture Radar data also open, things cannot get any better. Sure, I would love to have access to sub-meter or even cm level resolution to access on my dog's shitting and eating habits but I don't have millions right now and I definitely don't see myself building a robust, highly functional satellite constellation anytime soon. As they say, beggars can't be choosers but hey, we still have options here so it's all good.



What can be done with the data:

I have here outlined some simple ways to use multi-spectral data from such satellites that are open to you.

Notice how often Near-IR is used for indices

NDVI is, by far, the most popular index because of it's simplicity and relative accuracy


How the data can be utilized:

For the class I took back in school, we were allowed to use a cracked version of ENVI, a GIS software that allowed me to import product data from sites like USGS's Earth Explorer or ESA's Sentinel's Data Hub. However, there are tutorials out there that utilize open source software to pull data from these websites and analyze them for their own purposes.

Blog We Choose The Moon has a nice write up [HERE] on how to analyze vegetation using LANDSAT 8 data using open source software (codes ahead) while website digital-geography has shown [HERE] how Sentinal-2 data can be used for the same purpose.

A final note on Plant Labs:

To be able to pack an imaging system that maps earth at 3-5m resolution is quite something
Seen here is the co-founder of PlanetLabs, Will Marshal
showing one of the dove constellation, cubesat based satellite
Planet Labs has opened data on it's API for the state of California [HERE] for anyone who takes the time to apply for it. Even if the data accessed is two weeks old, access to data that is 3-5m GSD that updates everyday is just too good to be ignored. While the initiative to allow access to such high resolution data is accessed every year for continuity, such open data for Nepal would have enormous impact in understanding urban growth, public health problem distribution and agriculture production. I will see if I can request the company to do so for Nepal, although, they might have serious doubts as to what I might do with it. They should because not everyone should have access to such important information.

It could, however, be worth a shot. The world is a funny place anyways.

Comments

  1. Nice blog and this good to helping Nepal disaster victims and that should be best step for them. For more information visit website: -disaster in nepal

    ReplyDelete

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