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Big Earth Observation Data and Web GIS applications

Monitoring Earth’s Surface Water from Space

Data, Tools, and Algorithms

Gennadii Donchyts

Satellite Sensors and Measurements

DN Spectral Radiance Radiance Reflectance

Visible and invisible colors

Gorelick et.al., 2017, Remote Sensing of Environment

https://developers.google.com/earth-engine/datasets/

~20 Petabytes of data

Earth Engine

Storage and Compute

Landsat Satellite Data

Landsat images per year

1 50

cloudsshadows

TO

A r

efle

ctan

ce, %

Percentiles, %

clear pixels

10% 62%

cloudsshadows

TO

A r

efle

ctan

ce, %

Percentiles, %

clear pixels

Actual images vs. Reflectance Percentile Composites

http://www.earthenv.org/cloud

New Land New Water

Tools used App Engine (PaaS) Google Earth Engine API Google Maps API HTML / JavaScript

http://aqua-monitor.deltares.nl

Reservoir Monitoring

http://bit.ly/global_reservoirs_map_2016 GRanD ~= 6000, HydroLAKES ~= 1mln

Reservoirs

work in progress …

Combine multiple reservoir datasets (HydroLAKES)

Derive surface water area dynamics

Estimate storage

Reservoirs / Lakes

Donchyts, 2018, PhD Thesis

Discriminative vs. Generative

Water Mask vs. Water Occurrence vs. Water Changes vs. Underwater

0

1000000

2000000

3000000

4000000

14-11-1984 7-5-1990 28-10-1995 19-4-2001 10-10-2006 1-4-2012 22-9-2017

Surface water area estimated from satellite and from local water level station

* after outlier removal 0

2000000

4000000

0 2000000 4000000

A* (A)

RMSE < 0.059 km2

A = 0.5 – 3 km2

R2 = 0.991

Coastal Bathymetry

In-situ measurements Derived from satellites

Reconstructed inverse-depth bathymetry

Reservoirs

Coastal Areas

Rivers

Reservoirs

Lakes

Waterbody Types

Questions

How to harmonize all water datasets?

How to monitor surface water changes globally at 1m resolution?

How can we stop using Web Mercator (only) in Web Maps?

How to make Web GIS maps 4D?

How to mix satellite images, vector datasets and point clouds?

How to stream video in Web GIS?

What kind of web-based analysis tools are missing?