Cloudless Atlas with Landsat

May 29 2013 by Eric Gundersen

This is a peek at the next release of our Cloudless Atlas release that the satellite team is prepping. Our goal is simple: to create cloud-free imagery mosaics from satellite imagery at ever higher resolutions for the entire world.

This is a peek at the next release of our Cloudless Atlas release that Chris and Charlie on the satellite team are prepping. Our goal is simple: to create cloud-free imagery mosaics from satellite imagery at ever higher resolutions for the entire world. This new cloudless imagery will be rolled out to MapBox.com later this summer in addition to being available for our behind firewall products using vector tiles.

Southern Spain

Algeciras, Spain, and Gibraltar

Landsat 8 – The Future

This latest work with Landsat has us well positioned for future imagery processing. The big news in satellite imagery this week is that Landsat 8 is coming online. The Landsat program has run for more than 40 years, providing an unparalleled visual record of the Earth’s surface, and Landsat 8 promises to bring cleaner, more colorful images than ever. The satellite team has been working with the sample data that’s been released ahead of the official handover from NASA (which launched it) to USGS (which will operate it and provide the imagery), and they report that the new images look terrific.

The Landsat program has run for more than 40 years, providing an unparalleled visual record of the Earth’s surface, and Landsat 8 promises to bring cleaner, more colorful images than ever.

One reason Landsat 8 is so important is that its predecessor, Landsat 7, has suffered from a mechanical error for the last decade. Landsat 7 assembled images by moving a series of mirrors in zig-zag fashion to collect one small strip of imagery at a time – panning back and forth (as seen in the screenshot above), the way you might examine a large object through binoculars. But on May 31st, 2003, a small part broke and the mirror system no longer compensated for the satellite’s orbital motion. The image swaths no longer adjoined properly, and lines of missing data appeared:

Landsat 8 uses a new sensor system – it works a lot like a desktop scanner – to provide cleaner data more reliably. At the same time, it has sensor upgrades from Landsat 7, so it captures colors more faithfully. You can expect to find Landsat 8 imagery in our satellite layer for years to come.

Even though Landsat 8 isn’t online yet, we were able to smooth these images of Gibraltar from Landsat 7 by adapting the algorithms and processes we developed to remove clouds – basically we remove missing data exactly as if it were clouds. All the images in this post are produced from Landsat 7 data.

Landsat 7 images for path 201, row 35 (Strait of Gibraltar), captured between 1999 and 2013

The same images as they proceed through the null- and cloud-removal process

Output, with preliminary post-processing for angle and color. This cloud-free composite uses 30m Landsat imagery for the Strait of Gibraltar, with Spain on the north and Morocco on the south

In short, at the same time as we look forward to years of high quality Landsat 8 data to come, we’ve found a way to make good use of the last 14 years of Landsat 7 data, even SLC-off images that had seemed unusable until now.

We will continue to post status updates on Twitter via @MapBox, and Chris (@hrwgc) and Charlie (@vruba) on the satellite team always appreciate technical questions.