My Google Map Blog

Satellite imaging company DigitalGlobe recently wrote an interesting blog post about their vast archive of imagery and how they are moving it to the cloud.

Some interesting statistics from the post:
One image from WorldView-3 can be 30 gigabytes.
The DigitalGlobe archive is around 100 petabytes.
Their archive increases by 10 petabytes per year.

Comparing this to what we learned about Planet’s archive earlier this year, Planet has an archive of 7 petabytes. Before Planet launched the latest batch of 88 satellites and purchased Terra Bella from Google they were adding 7 terabytes daily or 2.5 petabytes per year to their archive. We estimate that they are now adding about two and a half times that daily or over 6 petabytes per year.

So, although Planet has the world’s largest imaging satellite fleet (actually, it is the world’s largest commercially-operated fleet of any type of satellite), their volume of imagery being gathered in terms of data storage required appears to be lower than DigitalGlobe’s. This is probably because DigitalGlobe’s satellites are higher resolution and thus produce much more data per area covered. It is also probable that DigitalGlobe’s satellites gather more optical wavelength bands.

DigitalGlobe have, until now, kept most of their archive in-house in a vast tape-based storage system. However, they are now moving to the cloud (Amazon Web Services). Rather than attempt to upload 100 petabytes to the internet, Amazon sent them a whole shipping container, a solution known as ‘Snowmobile’, complete with built in data storage, which DigitalGlobe then copied their data to and sent it back to Amazon. Interestingly, according to Amazon, 100 petabytes is the upper limit of their ‘Snowmobile’ solution (per truck).

We don’t know the exact size of the Google Earth database, but we estimate it to be several petabytes at least. So if you ever needed an offline version, then you would probably need a large suitcase-sized container at least.

The DigitalGlobe blog post features one of their images showing ‘Snowmobile’ outside DigitalGlobe’s headquarters but that image has not made it into Google Earth. However, we did manage to spot it in Street View:

Ground based imagery looking at an archive of satellite imagery.

The post How do you Move a Vast Imagery Archive? appeared first on Google Earth Blog.

DigitalGlobe recently released this article which highlights the use, by the Associated Press, of high resolution imagery from DigitalGlobe’s WorldView-3 satellite to combat slavery on fishing ships. You can read various Associated Press stories on slavery here and a story that specifically involved DigitalGlobe imagery here. The imagery is used to not only spot suspicious behaviour, but also identify ships from their masts and other distinctive features.

DigitalGlobe correctly claims that it is currently the world leader in resolution for commercial satellite imagery. It is likely that some countries have spy satellites with better resolution. Although the article mentions WorldView-3, DigitalGlobe also has WorldView-4, which was launched late last year and has similar resolution. WorldView-4 only went into commercial use this month.

We have previously looked at Global Fishing Watch, which monitors fishing ship locations and uses that information to identify illegal fishing. Maybe they too could help identify behaviour indicative of slavery on fishing ships. Apparently fishing ships carrying slaves spend most of their time at sea and offload their catch to other ships rather than returning to port.

The post DigitalGlobe is helping to combat slavery at sea appeared first on Google Earth Blog.

We recently came across this interesting article which talks about how DigitalGlobe is applying AI to satellite imagery recognition.

Humans brains are still extremely useful, so DigitalGlobe also has a crowd-sourcing platform that can be used either on its own, or to train an artificial intelligence algorithm.

If you are interested in AI and satellite imagery then read the DigitalGlobe developer blog, which has a number of interesting articles, such as:

Detecting and measuring coastal change
Finding pools
Monitoring changes along pipeline routes
Detecting population centers in Nigeria

Detecting population centers in Nigeria. [Image: DigitalGlobe]

You can also sign up for a free evaluation account on DigitalGlobe’s AI platform GBDX.

Incidentally, we also found this comment in the article mentioned in the first paragraph above to be interesting:

DigitalGlobe also doesn’t release images of active U.S. combat areas.”

This at least partially explains the censorship (lack of imagery updates) of certain countries in Google Earth. It is not clear whether this is a decision made unilaterally by DigitalGlobe.

The post Using artificial intelligence on satellite imagery appeared first on Google Earth Blog.

The next couple of days will see two significant launches for satellite imaging. If all goes well, the first launch will be four SkySat satellites owned by Google’s Terra Bella. They are expected to launch with a Peruvian reconnaissance satellite aboard a European Vega rocket. See the count down clock and more launch details here. The launch takes place from ZLV, Kourou, French Guiana. Next will be WorldView-4. It is a DigitalGlobe satellite with similar specifications to WorldView-3, the current leader in high resolution commercial satellite imagery. According to spaceflightnow.com the launch is scheduled to take place from SLC-3E, Vandenberg Air Force Base, California.

[ Update: We didn’t realise at the time of writing that PerúSAT-1 which is being launched together with the SkySat satellites is also an Earth observation satellite with a resolution of 70 cm per pixel panchromatic and 2 m per pixel for colour. Learn more about it here]

We already looked at WorldView-4 last month, so today we are focusing on the SkySat satellites. Those being launched today are SkySats 4 through 7. SkySat 1 was launched in November 2013, SkySat-2 in July 2014 and SkySat-3 in June 2016. We have seen imagery from them a number of times, including imagery of the damage caused by Italy’s recent earthquake, a poppy display at the Tower of London and the Burning Man festival. We also once came across a SkySat image in the Sahara, which has since disappeared from Google Earth.

The SkySat satellites have an imagery resolution of about 90 cm per pixel. This is not as good as WorldView-4’s 30 cm per pixel, but is better than Planet Lab’s Dove satellites, which have a resolution of 3-5 m per pixel. It is also better resolution than the best imagery Google Earth currently has for some locations, so we hope Google considers using Terra Bella imagery to fill in the gaps in Google Earth.

Unlike SkySats 1 and 2, SkySat-3 has propulsion, which gives it greater flexibility in capturing images. Presumably 4 thorough 7 also have propulsion. Read more about the differences between SkySat’s 1 and 2 and SkySat-3 here.

The SkySat satellites being prepared for launch as tweeted by CNES. Image credit ESA-CNES-ARIANESPACE.

The post WorldView-4 and SkySat launches appeared first on Google Earth Blog.

We recently came across this interesting article on the DigitalGlobe blog. It is about using imagery crowd-sourcing site Tomnod to count seals in DigitalGlobe satellite imagery of Antarctica. The very best commercial satellite imagery available today has a resolution of about 30 cm per pixel, with most imagery that we call ‘high resolution’ satellite imagery closer to 50 cm per pixel. This usually means that animals are only a few pixels in an image and difficult or impossible to spot. In the cases where we have seen animals in Google Earth it has typically been in aerial imagery, such as the National Geographic Africa Megaflyover images or areas like the US which have a lot of aerial imagery. And there is, of course, Street View.

Antarctica has the advantage that we are looking for dark spots on a fairly featureless white background, which makes spotting seals possible. Much of Antarctica doesn’t have high resolution satellite imagery but there are some areas that have DigitalGlobe strips of imagery. So, given the tips in the DigitalGlobe blog post, we wondered whether we could find any seals in the imagery.

We aren’t certain if these dark spots are seals, but they do match the description given.

This is rather low resolution imagery but it does look like there might be groups of seals gathered around this crack in the ice.

We are fairly sure this is a positive find and that those are seals.

For the locations above, download this KML file.

Despite looking rather white and boring from a distance, it is well worth zooming in on Antarctica and looking around, as there is a remarkable variety of landscapes formed by glaciers and shifting sea ice. For best results switch to ‘historical imagery’ as it is much easier to find the high resolution patches that way.

We also tried looking for seals with the Tomnod website, but were unsuccessful. Google Earth is a much better interface for this sort of thing as it is much easier to find major features, such as cracks in the ice, then zoom in to them. The actual survey the scientists want, however, has to be done on Tomnod, because Google Earth does not have access to all the imagery that they want searched.

The post Can we see Antarctic seals in Google Earth? appeared first on Google Earth Blog.

DigtialGlobe’s WorldView-4 is expected to be launched next month, on September 15, 2016. According to Wikipedia, WorldView-4 started life as GeoEye-2 back in 2007. However, DigitalGlobe bought GeoEye in early 2013. At the time, DigitalGlobe had a very similar satellite, WorldView-3, being prepared for launch and it was capable of seeing more wavelengths, most notably in the shortwave infrared. So, WorldView-3 was launched in August 2015 and GeoEye-2 was put on hold.

WorldView-4 isn’t so much a successor to WorldView-3 but more of a companion satellite and is being launched to increase capacity in line with greater demand for satellite imagery. A comparison of the advertised stats for the two satellites shows that WorldView-4 covers less spectrum, but is otherwise almost identical in capability to WorldView-3.

Read more about the development of WorldView-4 and its transport to the launch site here. One interesting fact pointed out is that one of the technical difficulties with imaging satellites, which typically travel at about 7.5 m per second, is to capture imagery without blurring. It helps, of course, to be over 600 km from the subject, but even then, as we saw with ‘rainbow planes’, the movement of the satellite can have a significant effect. Telescopes used for astronomy can have long shutter times, but imaging satellites do not have that luxury.

WorldView-4 has a 1.1 m mirror and weighs nearly two and a half tons. Compare that with Plant Lab’s dove satellites, which are 10x10x30 cm and weigh 4kg. The key difference is resolution, with WorldView-4 capable of 30 cm per pixel and the doves around 3 to 5 m per pixel.

Planet Lab’s satellites are based on the CubeSat concept, which aims to standardise small satellites for cost savings. Incidentally, the WorldView-4 launch will include seven CubeSats (not for imaging) as part of a ride share agreement with DigitalGlobe.

image credit: DigitalGlobe.

The post WorldView-4 appeared first on Google Earth Blog.

In yesterday’s post we suggested that the reason for the near polar orbit of most imaging satellites was to improve coverage. After a bit more research it turns out to be more interesting than that. Apparently there is a special orbit called Sun-synchronous orbit, which is designed such that the satellite always crosses a given latitude on the ‘day’ side of the Earth at the same time of day. This has two benefits:

• if two neighbouring images, or images of the same location are captured on consecutive passes of the satellite, they will have the same lighting (both the overall brightness as well as the length and direction of shadows), which makes it much easier to stitch them together in the case of side by side images or comparing for changes in the case of images of the same location.
• the orbit can be positioned such that the satellite is always overhead as close to noon as possible (or whatever time is considered the best for imaging) for the latitudes of greatest interest. A non Sun-synchronous near polar orbit would result in some days when the satellite is orbiting in a plane at 90 degrees to the direction of the sun, which would make it constantly sunrise or sunset.

A Sun-synchronous orbit has a particular inclination depending on the altitude of the satellite. The lower the altitude, the closer the orbit is to the north-south direction. For a table of altitude vs. maximum latitude, and other technical details, see Wikipedia.

As far as we can tell almost all imaging satellites are in Sun-synchronous orbit, including SkySat-1 and SkySat-2. They also all have altitudes in the 500-900 km range, meaning they should all have similarly tilted orbits with a maximum latitude of around 82 degrees.

Thank you to GEB readers franksvalli2 and Vasilis for letting us know that the mystery image in yesterday’s post is almost certainly from one of the SkySat satellites. See this PDF file for details on those satellites, including their sensor arrangements which creates the distinctive ‘Y’ pattern. Also thank you to GEB reader Daniel Plant for bringing our attention to TeLEOS 1, which, as you can see here has a very different orbit.

We used our circle drawing tool to estimate the orbit of the satellite that took yesterday’s image and it came remarkably close to the expected 82 degree maximum latitude.

Although DigitalGlobe imagery in Google Earth is typically in both vertical and horizontal stripes, we believe that the imagery is actually captured by a satellite following a Sun-synchronous orbit very similar to the Sky-Sat orbits. We believe that the almost perfect north-south or east-west alignment of the DigitalGlobe strips is for some reason other than orbit. We have noted in the past that they line up with degrees of latitude and longitude.

For more interesting reading about orbits see this article from NASA.

The post Sun-synchronous orbit appeared first on Google Earth Blog.

Saab and DigitalGlobe have announced a new joint venture called Vricon. It will be a Google Earth like product featuring 3D models similar to the 3D mesh that Google is rolling out. The key difference is that Vricon is using DigitalGlobe’s satellite imagery to create the 3D, whereas Google uses aerial imagery that must be specially captured for the areas they wish to map. This means that although Vricon’s imagery will necessarily be of lower resolution, it can have far greater reach and can be produced from the already existing DigitalGlobe archives. Also of note is that this is a commercial product targeted at enterprises and governments, whereas Google Earth is a free product.

Learn more about it and how it is produced in this article from Time magazine.

To see sample 3D imagery see the various demonstration videos at Vricon’s home page. For a tour of various locations look under “Capabilities->Explore Vricon 3D data”.

New York as seen in a Vricon promotional video.

The same location as seen in Google Earth.

As you can see above, the Vricon 3D model struggles with the gaps between buildings. Google’s 3D models often have similar problems but it is more pronounced in the Vricon model due to the lower resolution. Also of note in the New York images above, the Vricon model seems to have completely failed with the new World Trade Centre towers. This is likely due to the fact that they use satellite imagery from a range of dates, including during the World Trade Centre construction, which would have confused the algorithms used to create the 3D.

Beijing, China, as seen in a Vricon promotional video.

One of the locations featured in the promotional videos, is Beijing, China. Google has not yet released any 3D for China – possibly due to the difficulties in getting clearance from the Chinese government. However, with satellite imagery no such clearance is necessary. So maybe Google should consider using a similar technique to provide lower resolution 3D in areas where they cannot gather aerial imagery. The only problem is that Google does not have access to the full archive of DigitalGlobe satellite imagery, and now that DigitalGlobe has the commercial Vricon product, they might be reluctant to allow Google to use their imagery to create a free version. There are, however, other satellite imagery providers that might be willing to work with Google. DigitalGlobe, however, has the highest resolution satellite imagery available coming from their WorldView-3 satellite.

The post Saab and DigitalGlobe working on 3D globe appeared first on Google Earth Blog.

Most oil platforms can not be seen in Google Earth. This is because Google and its imagery providers do not bother with imagery of the oceans far from the coast unless there is something of particular interest. Back in 2006 Google Sightseeing was able to find a few oil platforms in Google Earth’s imagery, which they showcase in this post.

In March we told you about DigitalGlobe’s First Look program and its public map showing where imagery has been captured of particular events. One such event was an explosion on an oil rig in the Gulf of Mexico on April 1st, 2015. DigitalGlobe captured imagery of the location on April 5th, which shows an oil slick coming from the platform.

To find the location of the oil rig above in Google Earth download this KML file.

Several images from before and after the event have been added to Google Earth in the area and a number of other oil rigs can be seen in the imagery. The imagery can only be seen in ‘historical imagery’. Many of the oil rigs show plumes of smoke but these are normal gas flares. If you turn on the ‘Earth City Lights’ layer (found in Gallery->NASA), you will notice a very bright area where the above oil rigs are due to the gas flares.

If you turn on the ‘photos’ layer you can find a number of pictures of oil rigs in the region.

The post Oil Slick from Oil Platform Explosion in Google Earth appeared first on Google Earth Blog.

Last week we had a look at Digital Globe’s FirstLook service and some imagery of the damage done by Cyclone Pam to Vanuatu.

We have been going through some of the locations from the DigitalGlobe FirstLook Coverage map and finding them in Google Earth. Some locations we have covered in the past such as:

• The tornado damage in the towns of Pilger and Wessington Springs, USA
• The crash site of Malaysian Airlines flight 17
• The Koslanda landslide in Sri Lanka.

There are, however, a few locations that we have not covered before that have relevant imagery in Google Earth and you can see the events in question. The ones we have found so far that you may find interesting are:

A train derailment in India.

A volcanic eruption in Gifu and Nagano Prefecture, Japan.

The 2014 Glastonbury Festival.

May Day celebrations in Moscow.

To find the above locations, and a few more interesting ones in Google Earth, download this KML file. You may need to move the ‘historical imagery’ slider to find the correct image(s). Remember that sometimes the event is captured on more than one date.

The post Another look at DigitalGlobe’s FirstLook coverage appeared first on Google Earth Blog.