Monthly Archives: July 2016

High-Resolution Population Density Mapping by Facebook and DigitalGlobe

Few months back, we all read the news that Facebook has utilized satellite imagery to generate an estimate of population density over different regions of the Earth. This task was accomplished by Facebook Connectivity Lab, with the goal to identifying possible connectivity options for high population density (urban areas) and low population density (rural areas). These connectivity options can range from Wi-Fi, cellular network, satellite communication, and even laser communication via drones.

Facebook Connectivity Lab found that current population density estimates from censuses are insufficient for this planning purpose, and resolved to make their own high spatial resolution population density estimates from satellite data. What they did was take their computer vision techniques developed for face recognition and photo tagging suggestions in images and applied the same algorithms to analyzing high-resolution satellite imagery (50 cm pixel size) from DigitalGlobe. DigitalGlobe’s Geospatial Big Data platform was made available to Facebook, along with their algorithms for mosaicking and atmospheric correction. The technical methodology employed by DigitalGlobe and Facebook Connectivity Lab, is detailed in this white paper by Facebook. DigitalGlobe’s high resolution satellite data from the past 5 years or so (imagery from high-resolution WorldView and GeoEye satellites), were utilized, and they only used cloud-free visible RGB bands. For cloudy imagery, third party population data was used to fill in the gaps. On this big geospatial dataset from DigitalGlobe, the Facebook team analyzed 20 countries, 21.6 million square km, and 350 TB of imagery using convolutional neural networks. Their final dataset has 5 m resolution, particularly focusing on rural and remote areas, and improves over previous countrywide population density estimates by multiple orders of magnitude.




Augmented Reality Sandboxes

Scientists have put Microsoft / Xbox Kinect sensors to great use over the years. One of these uses is in simulation of physical effects in terms of geography and mapping, ranging from topography to water flow. By now, many of these augmented reality interactive sandboxes are in action.

One of the most popular of these toolboxes is the aptly-named Augmented Reality Sandbox built by the UC Davis W.M. Keck Center for Active Visualization in the Earth Sciences for an NSF-funded project on informal science education. Learn the latest updates, and keep up with developments on the project page here and here. This sandbox works with a Kinect 3D camera and a projector to project a real-time colored topographic map with contour lines onto the sand surface. Mathematical GPU-based simulations govern the virtual water flow over the surface. This sandbox is already an interactive display at the University of California Davis Tahoe Environmental Research Center (TERC) and the Lawrence Hall of Science at University of California, Berkeley, among many other places. There are some cool demo videos for this sandbox, depicting real-time water flow simulation with respect to topography and virtual dam failure simulation, among others.

See a detailed article on Wired about this sandbox here.

A company from the Czech Republic offers their SandyStation augmented reality sandbox. Two good lists and descriptions of other virtual reality sandboxes all over the world are available here and here.

The Definition of Research

Recently I came across an interview of the renowned Pakistani physicist and social activist Dr. Parvez Hoodhbhoy in the MIT Technology Review Pakistan. Among many other interesting things discussed and mentioned there, I found his definition of research most interesting, which I am copying below:

Research in any professional field — mathematics or physics, molecular biology or engineering, economics or archaeology — does not have a unique, precise definition. But a tentative, exploratory definition might be that research is the discovery of new and interesting phenomena, creation of concepts that have explanatory or predictive power, or the making of new and useful inventions and processes. In the world of science, the researcher must certainly do something original, not merely repeat what is already known. Just doing something for the first time is not good enough to qualify as research. So, for example, one does not do meaningful research by gathering all kinds of butterflies and listing the number caught of each kind in a particular place at a particular time, etc. Nor does it come from making standard measurements, substituting one material after the other just because “it’s not been done before.” That’s mere alchemy, i.e., pretty useless.