Science

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Oceans on Mars

April 27, 2015

We were recently reading this story from NASA that says Mars used to have large oceans. It includes a tantalizing picture reminiscent of Google Earth. So we decided to see if we could simulate oceans in Google Mars.

We have looked at a number of stories in the past where people have used KML to simulate sea level rise:

However, it turns out this technique doesn’t work over large areas. KML polygons set to fixed altitude do not curve with the earth’s surface.

So, instead, we found a digital elevation model (DEM) map of Mars provided by NASA that can be obtained from here. We then used an image editing program to colour the lower elevations blue and make higher elevations transparent. We then took the resulting image and made an image overlay and you can see the result below:

For an even more realistic effect, we combined our ocean with this Mars map also from NASA. Then we used it in an image overlay on the Earth, instead of Mars, which enables us to turn on the ‘Clouds’ layer, giving the result seen below:

The NASA image did not have clouds, but the picture on this Wikipedia page does. Without plants, the land would not have been green like much of the Earth is.

To try these out for yourselves, download these KML files: Mars Ocean
Mars Ocean and Land. The second one is best viewed with all layers turned off except the ‘Clouds’ layer (found in the ‘Weather’ layer).

The maps may not be scientifically accurate, as we don’t know whether the elevation data in the NASA maps takes into account the equatorial bulge that is created due to rotation. On Earth we usually calculate elevation above or below Sea Level, but that doesn’t work on Mars as it doesn’t have a sea.

The history of aerial photography

August 25, 2014

With the successful launch of the imaging satellite WorldView-3 by DigitalGlobe recently, featuring the latest technology in satellite imaging, it is a good time to take a look at where it all started.

The very first aerial photograph was taken from balloon by the French photographer and balloonist Gaspard-Félix Tournachon, in 1858 over Paris, France. However, the photographs he produced no longer exist and therefore the earliest surviving aerial photograph is titled ‘Boston, as the Eagle and the Wild Goose See It’ and was taken by James Wallace Black in 1860, also from a balloon.

Kite aerial photography was pioneered by British meteorologist E.D. Archibald in 1882.
The most interesting method of aerial photography is pigeon photography, a technique invented in 1907.

By World War I aerial imagery taken from aircraft was being used for reconnaissance and the technology matured rapidly as a result.

The first images from space were taken in 1946 from a suborbital U.S.-launched V-2 rocket.
In 1972 the United States started the Landsat program, the largest program for acquisition of imagery of Earth from space.

Historical imagery was introduced to Google Earth with version 5 in 2009.

The oldest imagery that can currently be found in Google Earth is from 1930, near Toronto, Canada. To view it in Google Earth you need to turn on “Historical Imagery” pan to the region around Toronto, Canada, then move the slider all the way to the left and the imagery will show up as black and white areas, or simply download this KML file. There is also quite a lot of historical imagery from the Second World War in parts of Europe, with significant portions of the UK having imagery from 1945 or earlier.

It is important to note that although satellite imaging has many advantages, for the highest resolution aerial imagery, airplanes are still used today and most of the high resolution imagery in Google Earth was captured from aircraft.

Creative cat tracking in Google Earth

August 20, 2014

Here’s a fun use of Google Earth and GPS — tracking cats. It started when Tiana Warner at safe.com found out about a way to track cats:

Where do cats go when they’re outside all day and night? What do they do? How do they entertain themselves? Is there a secret cat meeting place in every major city? When Safers found out about Cat Tracker, we couldn’t resist.

The result is pretty neat.

While it’s mostly a fun little project, the technology behind it is remarkably complex. Get the GPS data from Movebank in JSON format, flatten it, create a “convex hull” around the main area, clean up GPS anomalies, rank the cats based on travel area sizes, then push it out via KML. Here is a KML file to view it for yourself in Google Earth.

You can read more on the Safe Software Blog.

Google Earth instrumental in discovery of new chameleon species

August 19, 2014

Back in 2005 Julian Bayliss, a biologist at London’s Kew Gardens, discovered a brand new rainforest that had previously never been studied — and he found it using Google Earth. We told you about it in May this year, and you can watch a short video about the discovery below.

Since then, many new species have been discovered at the location, known as Mozambique’s ‘sky islands’, including a snake, a butterfly, and most recently, the recent discovery of four new pygmy chameleon species.

Rhampholeon nebulauctor. Credit: Julian Bayliss.

Rhampholeon tilburyi. Credit: Krystal A. Tolley.

Rampholeon Maspictus. Credit: William R. Branch.

Rhampholeon Bruessoworum. Credit: Julian Bayliss.

Find the full story on Fauna & Flora International.

DigitalGlobe launching their WorldView-3 satellite today

August 13, 2014

DigitalGlobe, one of the leading providers of imagery for Google Earth, is launching their new WorldView-3 satellite in a few hours. It is scheduled to launch at 11:29am PDT today from Vandenberg Air Force Base, and you can watch a live broadcast of the launch here.

The new satellite will feature some great enhancements over previous ones, including:

Will capture imagery at 31 cm resolution, the highest available resolution on the market. This allows you to see not only a car, but the windshield and the direction the car is going. Something as small as home plate can be seen with 31 cm resolution.
Due to its shortwave infrared sensor, the satellite can actually image through haze, fog, dust, smoke and other air-born particulates.
Beyond crop mapping, this satellite will actually be able to identify moisture levels, differentiate between healthy and unhealthy crops, and even classify species on the ground.
The satellite can identify types of minerals on the earth’s surface
It can identify not only a tree’s class and species, but its health as well

It should be a great step forward for imaging, and ultimately for Google Earth. Check out the infographic below for an overview of the satellite, visit worldview3.digitalglobe.com for more information, and watch the launch live in a few hours.