

Start Using Landsat on AWS - mxfh
https://aws.amazon.com/blogs/aws/start-using-landsat-on-aws/

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mthoms
Does anyone know the resolution of the images available through AWS? This site
[http://landsat.usgs.gov/landsat8.php](http://landsat.usgs.gov/landsat8.php)
says Landsat 8 has a max resolution of 30m/pixel.

~~~
jeffbarr
I checked in with Jed (the guest blogger) and he told me that Band 8 of the
data has the highest (15m) resolution. Per the post at
[https://www.mapbox.com/blog/putting-landsat-8-bands-to-
work/](https://www.mapbox.com/blog/putting-landsat-8-bands-to-work/) , you can
use this to sharpen the images in the other layers.

~~~
celoyd
_I wrote that Mapbox post, and helped with some of the processing that happens
to get this data on AWS._ Yep, you get multispectral resolution of 30 m, and
with pansharpening
([http://en.wikipedia.org/wiki/Pansharpened_image](http://en.wikipedia.org/wiki/Pansharpened_image),
etc.) you can get visually acceptable quality at 15 m in RGB.

Landsat is basically intended for science about seasonal/annual/decade-scale
changes in Earth’s land surface. When you see an estimate of how a city’s
built-up area has grown since 1980, or how the Everglades are changing, it
probably has Landsat as one source. This explains a lot of design decisions
that might seem weird to a layperson who wants to use it for everyday RGB
imagery. Most use of Landsat imagery is basically off-label. It’s just _very
good data_ in terms of accuracy, precision, and general ease of use. And if I
say so myself, it looks real pretty: [https://www.mapbox.com/blog/landsat-
live-live/](https://www.mapbox.com/blog/landsat-live-live/)

~~~
sjtrny
Which pansharpening method is used in the example image?

~~~
celoyd
In the images in the blog post and the live map? Those aren’t pansharpened at
all. If we do add pansharpening in a later version, it’ll likely be naïve,
without spatially aware modeling of the multispectral data. (Specifically,
it’ll probably be a cleaned-up, rasterio-based, null-aware, parallelized
descendant of this sketch of the Brovey transform in numpy:
[https://gist.github.com/celoyd/2e7beed82951d22b9b90](https://gist.github.com/celoyd/2e7beed82951d22b9b90)
.)

From what I’ve seen – and I haven’t tested it carefully yet, so I could be
wrong – the more elaborate methods are severe overkill on Landsat 8. It has
only 4 pan px per multi px (where some commercial data has 9 or 16), and the
pan band is almost exactly R+G+B (without NIR). So my gut and some simple
experiments suggest that doing PCA-or-whatever is overthinking it.

~~~
sjtrny
In the blog post

> Pansharpened Malibu, 15 m (50 ft) per pixel. Notice the wave texture in the
> water.

Ugh, Brovey. There's better options available. Like MMP (really low spectral
distortion but can be slow):
[http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6677587](http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=6677587))
or even affinity/guided filtering (my own paper, more spectral distortion than
MMP but a lot faster and you can sharpen hyperspectral with multispectral or
RGB):
[http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=7008094](http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=7008094).

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Demiurge
It would be most useful if historical Landsat 7 data was also available, but
of course that is a lot more data.

~~~
jeffbarr
We will definitely consider adding more data over time.

~~~
Demiurge
Great! That would be an amazing resource saver and enabler for scientists as
well as small companies, incentivizing the use of AWS, as opposed to in-house
built systems.

