My Google Map Blog

We often feature imagery from the European Copernicus programme’s Sentinel-2 satellite. The programme has other satellites, including Sentinel-1A and Sentinel-1B, that gather radar data rather than imagery. They seem particularly good at measuring altitude changes over time. For example, we saw a map of surface deformation after a major earthquake in Chile.

A recent story on the European Space Agency (esa) website is about how the satellites have been able to determine that the Millennium Tower, a sky scraper in San Francisco, is sinking by a few centimetres per year relative to other buildings in the vicinity.

Image credit: ESA. The colour scale ranges from 40 mm a year away from radar (red) to 40 mm a year towards radar (blue). Green represents stable targets.

Given the sensitivity of this data it makes us wonder whether or not Google could use it to improve the accuracy of their altitude data. We have noted in the past some fairly major errors in their data, such as the sunken island of Gorgona and significant inaccuracies around Rio de Janeiro.

The post The sinking Millennium Tower, San Francisco appeared first on Google Earth Blog.

Earlier this week Google added to Google Earth global mosaics based on Landsat and Sentinel 2 data from 1985 to 2016. Google Earth Engine provides animations for the data using a web based interface. We promised to release a way to animate the data in Google Earth.

Simply download this KML file and open it in Google Earth. Then switch to ‘historical imagery’ and find a location of interest then play the ‘Animation’ tour found in the KML. If you wish to move to a different location, close the tour, move to the new location, wait a moment, then open it again. Depending on your internet speed, either let the tour run through a couple of times to load all the imagery, or you can manually go through each year first to make sure it is loaded, then run the tour to see it animated.

Speed in milliseconds per image:

The growth of Kuala Lumpur, Malaysia, over 30 years (1985-2016) using the new Google Earth global mosaics.

The imagery covers a period of just over 30 years and there is almost no place on the planet that hasn’t changed significantly in that time, so get exploring!

Remember these are long term changes, not month-to-month changes.

We chose a timing of one second per image. We would have liked to go faster, but Google Earth cannot handle faster tours and starts to skip images if you increase the speed.

The post Animating the new Landsat/Sentinel global mosaics with a dynamic tour appeared first on Google Earth Blog.

Yesterday Google surprised us by adding global mosaics created from Landsat and Sentinel 2 data to the Google Earth’s ‘historical imagery’. The data comes to Google Earth via Google Earth Engine, which has long had this time-lapse feature that has just been updated to include imagery up to 2016. The timelapse page also tells us more about the imagery:

Using Earth Engine, we combined over 5 million satellite images acquired over the past three decades by 5 different satellites. The majority of the images come from Landsat, a joint USGS/NASA Earth observation program that has observed the Earth since the 1970s. For 2015 and 2016, we combined Landsat 8 imagery with imagery from Sentinel-2A, part of the European Commission and European Space Agency’s Copernicus Earth observation program.”

Google Earth Engine has also published this post about the update.

On Friday we will release a KML file that will allow you to view similar time-lapses from directly within Google Earth.

Today we are making a few observations about the imagery.

The first observation comes from GEB reader ‘haflaa’ who points out that although the mosaics are global for every year between 1985 and 2016, there are some locations, such as the Maldives, where the imagery is identical for a number of years. In the case of the Maldives, the imagery is identical from 1985 to 1999.

We also note that the Google Earth Engine animation starts in 1984, whereas the Google Earth data starts with December 1985 (which we presume represents the data for the whole of 1985).

The path of the satellite is often noticeable in the imagery. For more on the orbit of the Landsat satellites see this post and this post.

In many locations you will notice narrow stripes in the imagery. This is because of a faulty part on the Landsat 7 satellite. Learn more about it in this post.

The mosaics are created by trying to select imagery from throughout a given year then selecting cloud and snow free pixels where possible. However, there are a few locations on earth that are almost always cloudy, a problem we discussed in this post.

This location in Cameroon features both Landsat 7 stripes and clouds that just could not be eliminated.

The post More about the new Landsat / Sentinel 2 data in Google Earth appeared first on Google Earth Blog.

Thank you for GEB reader Jonah for being the first to let us know. Google has added yearly global mosaics using Landsat and Sentinel 2 data going back to 1985. Google has long had these mosaics on Google Earth Engine which also provides a ‘Timelapse’ tool. As of this writing, the Google Earth Engine timelapse only goes up to 2012, but that will likely be updated too.

To see the mosaics, simply zoom out a bit and switch to ‘historical imagery’.

We plan to create tools to animate the new data, but that may take a few days.

Here are a few ‘before and afters’ showing changes between 1985 and 2016.

The Amazon, 1985 vs 2016

Dubai, 1985 vs 2016

The region around Shenzhen, China, 1985 vs 2016

Note that the new data is created by blending all Landsat/Sentinel 2 data for a whole year to remove clouds and snow cover. The result is that changes that happen on timescales less than a year, such as seasonal changes, will not be visible.

Google has not (as of this writing) updated the historical imagery layer with all the high resolution imagery that has been added since June 2016.

There is one disadvantage to the new data – it is much harder to find historical imagery, as you need to zoom in very close to the earth to see the high resolution historical imagery.

The post Google Earth now has global Landsat and Sentinel 2 data from 1985 to 2016 appeared first on Google Earth Blog.

On November 14, 2016, the South Island of New Zealand experienced a 7.8 magnitude earthquake named the Kaikoura Earthquake after the town of Kaikoura near the quake’s epicentre. The affected region is mountainous with steep slopes and the earthquake resulted in a large number of landslides, including creating some landslide dams (a topic we have covered in the past).

The Landslide Blog has done a number of posts on the Kaikoura landslides (1, 2, 3 and 4). It also mentions this article, which shows a map of the locations of the landslides so far identified using Sentinel 2 imagery.

We thought it would be interesting to examine the sentinel 2 Imagery in Google Earth. The image in question has quite a lot of cloud cover, but in the gaps between the clouds we can see the scars of a large number of landslides. It must be noted that landslides appear to be common in the region, with many landslide scars being visible in older imagery, too. Here are a couple of ‘before and afters’ showing just how many landslides there were in some places.

After image: Copernicus Sentinel data, 2016.

After image: Copernicus Sentinel data, 2016.

We processed the Sentinel 2 imagery using GeoSage’s Spectral Discovery.

To explore the Sentinel 2 imagery for yourself using Google Earth download this KML file

The post The Kaikoura Earthquake Landslides appeared first on Google Earth Blog.

On July 17th, 2016 there was a very large avalanche in the Aru Mountains of Tibet. This was followed by a second avalanche on 21st September, 2016. Planet Labs captured some imagery of the location of the second event and have created an excellent before and after, which you can find here.

For a more detailed analysis of the events see the excellent Landslide Blog Part 1 and Part 2. The Landslide Blog also includes some before and after images of the first event, which come from this page. One is a Sentinel 2 image captured after the first avalanche, and the other is a Landsat 8 image captured before the avalanche.

Now, there is Sentinel imagery available from after the second event we can do a full sequence:

January 23rd, 2016. Copernicus Sentinel Data, 2016
 

July 21st, 2016. Copernicus Sentinel Data, 2016
 

October 16th, 2016. Copernicus Sentinel Data, 2016
 

We have also put the Planet Labs images and the above Sentinel images into Google Earth. To view them download this KML file. The Sentinel imagery is actually slightly higher resolution than what you see above.

The post Avalanches in Tibet appeared first on Google Earth Blog.

We recently came across this interesting article on Bellingcat which is about the use of environmental damage as a weapon of war in Iraq. As the Islamic State (IS) is being pushed back, they are setting light to oil wells, pouring oil on the streets and in trenches and setting light to it and also setting light to other industrial products such as sulphur.

The article features some Landsat imagery showing the plumes of smoke. Landsat imagery is freely available, and we have in the past created a KML file that can make animations with Landsat imagery. If you download the KML file and view the animation for the area around Mosul, Iraq, you can clearly see the smoke in the last few images. Also of note, you can see some smoke from a previous event in an image from August 2014 to the north west of Mosul. We have also created animations using Sentinel 2 imagery, which you can download here.

The animations above are created using low resolution thumbnails provided on Amazon Web Services (AWS). To see some high resolution imagery, we downloaded the most recent Landsat-8 image and processed it with GIMP using a method similar to the one described here and here.

The result can be seen below:

Landsat 8 image from October 20th, 2016. Note the sulphur fire marked with an arrow. The black smoke is from oil fires.

For comparison, we also downloaded a Sentinel 2 image from September 14th 2016.

Sentinel 2 image from September 14th 2016. This is before the sulphur fire was started. Copernicus Sentinel Data, 2016.

See the above images in Google Earth, download this KML file.

The Bellingcat article also features an image of the sulphur fire from Planet Labs.

The post The fires of Qayyara, Iraq, with Landsat and Sentinel imagery appeared first on Google Earth Blog.

Google has just announced the release of Landsat and Sentinel-2 data on the Google Cloud. Landsat and Sentinel-2 data are public datasets of satellite imagery from earth observation satellites. The Landsat data is from a joint program between US Geological Society (USGS) and NASA and the Sentinel-2 data is from the European Space Agency’s Copernicus program.

Google has long had the datasets in Google Earth Engine, but accessing it required a Google Earth Engine account, which had certain restrictions on usage. The Google cloud version appears to be without restrictions. The data itself is public data and you can do almost anything you like with it although proper attribution may be required.

More about the individual datasets and how to access them can be found here: General instructions, Landsat, Sentinel-2.

The imagery is provided as unprocessed tiles for each of the optical bands that each satellite provides. To see the images in colour requires processing. The easiest way to do this is with commercial tools from GeoSage. Alternatively, see this post for instructions on how to process Sentinel-2 imagery using GIMP. Landsat data can be processed in a similar way, although it an some extra steps are required to get the best resolution.

The resolution of Sentinel-2 imagery is 10 m per pixel and Landsat-8 is 15 m per pixel after pan-sharpening. Do not expect to see the kind of detail we are used to in Google Earth.

Sadly, Google has not provided thumbnails with the data.

Amazon provided Landsat data via its cloud infrastructure Amazon Web Services (AWS) in 2015 and more recently added Sentinel-2 data. We did a series of posts featuring KML tools to allow you to preview the latest images and make animations from provided thumbnails. The Landsat data on AWS is somewhat limited compared to the Google Cloud offering. Google is providing all Landsat images from Landsats 4,5,6,7 and 8 from 1982 to present. AWS only has Landsat 8 data and even that is only complete data for 2015 and select images from 2013 and 2014.

The image below is a Sentinel-2 image downloaded from the Google Cloud and processed with GIMP. It shows a small part of the Soberanes Fire, California, on September 12th, 2016. To see it in Google Earth (and covering a larger area) download this KML file

Copernicus Sentinel data, 2016.

The post Landsat and Sentinel-2 data now on Google Cloud appeared first on Google Earth Blog.

We have recently been doing a series of posts about Sentinel and Landsat imagery on Amazon Web Services (AWS). We created tools to let you quickly preview the latest Sentinel and Landsat imagery in Google Earth. We also looked at the coverage pattern for the Sentinel and Landsat imagery and created a way to animate the Landsat imagery. Today we are releasing similar animations for the Sentinel imagery.

To see the animations, simply download this KML file, open it in Google Earth and click on any tile.

There are several differences between this one and the Landsat animations. The sentinel thumbnails are much lower resolution than the Landsat thumbnails, so we don’t provide a link to a larger version. Also, the sentinel images often do not cover the complete tile, so we have provided an extra slider to allow you to filter out tiles based on how much of the tile they cover.

The KML file also shows with colour coding how much sentinel imagery there is, with a range from green to red for 1 to 120 images per tile and white for tiles that have over 120 images. The highest numbers can be found over Europe, which is understandable given that it is a European satellite. The amount of imagery also increases towards the north of Europe, we believe this is because the paths the satellite takes overlap more near the poles, allowing more imagery to be captured. There are also hotspots over deserts suggesting that the images are selected for low cloud cover.

The Sentinel-2A satellite that is gathering the imagery was launched in June 2015. In comparison, Landsat 8 has been around since 2013. However, the Sentinel-2A satellite covers the globe roughly every 10 days, whereas Landsat 8 takes 16 days. In addition, the Landsat 8 archive on AWS only includes selected images from 2013 and 2014 (with significantly more of the US than other parts of the world) and only has the complete set of images from 2015 onwards.

We also find the clouds look whiter and obstruct the picture more in the Sentinel imagery than they do in the Landsat imagery. This may relate to how the imagery was processed for the thumbnail or it could reflect differences in the exact wavelengths the respective satellites use to capture the colour bands.

We came across a few errors in the data, such as mislabelled tiles or missing thumbnails, but they were not significant enough to seriously affect the operation of the animations.

As with the Landsat imagery, it is important to note that this is very low resolution imagery, so expect to only see very large scale phenomena. Also, with only a year’s worth of data there is not a lot of change to see. However, it is a continuously updated service and with the expected launch of Sentinel-2B sometime next year doubling the frequency of imagery, we can expect some spectacular animations in years to come.

The post Animating Sentinel-2 imagery in Google Earth appeared first on Google Earth Blog.

Yesterday we created a KML file that allows you to preview the latest sentinel imagery using a KML file of all the sentinel tiles. We noticed that some tiles do not have any images available, so we thought it would be interesting to do a map of Sentinel coverage. There are 56,686 tiles, so it took a little while to check all of them to see whether they have imagery and what the date of the latest image is. It turned out that only about half the tiles (27,256) actually have imagery.

We have colour-coded the tiles based on the age (in weeks) of the most recent imagery. As you can see, there is a distinct stripy pattern and the shape of the sun-synchronous orbit is clearly visible. Also of note is that imagery off the coasts and of Antarctica is not as recent as that over the continents.

To see it in Google Earth, download this KML file. Click on any tile to see the date of the latest image available (as of August 15th, 2016).

While creating the above KML we identified a few bugs in yesterday’s KML file, most notably that tiles starting with ‘0’ were incorrectly reporting no imagery. We have fixed the bug, so if you plan to use it then please re-download it from yesterday’s post.

The post Sentinel imagery coverage appeared first on Google Earth Blog.