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Posts Tagged ‘imagery’

Copernicus Earth Observation Programme – Data and Information Access Services (DIAS)

August 13, 2019 1 comment

To facilitate access to the European Space Agency’s (ESA) Copernicus earth observation data (Sentinel satellites), the European Commission has funded five cloud-based platforms, known as the Data and Information Access Services (DIAS), to provide users with easy access to data from the various satellite missions. The data are available on the platforms, subject to account registration, as both open data and on a pay-per-use basis.

The following examples of data search and download options were taken from the WEkEO data service. The other data hosting services include ONDA, numdi, sobloo  and CREODIAS.

The raw data are available as NetCDF (.nc) files on the WEkEO site, an example of which is shown here using the Panoply data viewer.

There are various tools available to convert NetCDF files to more GIS friendly formats such as the Marine Geospatial Ecology Tools, a free add-on for ArcGIS that converts NetCDF to ASCII and ArcGrid formats.

 

 

 

Categories: Public Domain Data Tags: , ,

The Top 12 Most Useful Landsat Image Sites

August 4, 2019 4 comments

Recently, I wrote an essay about the sites that are, in my judgment, the top 10 in terms of containing useful geospatial data.   Now, I would like to describe what I consider to be the top sites for Landsat satellite imagery in terms of content and ease of use.  Let’s limit it to the Top 12.  Why might such a list be helpful?  First, there is no “one single site” to obtain Landsat data, and second, the sites are in continual flux, with some such as the Global Land Cover Facility disappearing and some having recently been created.  As with any consideration of data portals, make sure you have done a careful assessment of your data needs–band combinations, resolutions, formats, streamed services vs. downloaded files, dates, how many files you need, and so on, to guide you before you start searching.

(1)  The DevelopmentSeed’s Libra Portal.  I recently used this resource to include in the update (to ArcGIS Pro) for the Brazil land use change lesson that we host on the Spatial Reserves set of 10 hands-on exercises.  We wrote about the Libra portal here, and it remains in my judgment a no-nonsense resource that is easy to use with a wealth of options and data.

(2)  The EOS Data Analytics Landviewer, as we described here, is very useful and user friendly.   The EOS staff also wrote this helpful review of imagery sites.  Like the DevelopmentSeed portal, I find its user interface to be very straightforward.   The Landviewer includes Sentinel-2 and other imagery, as well.

(3)  Esri’s ArcGIS Living Atlas of the World has made amazing strides in content and usability since we first wrote about it here.  Most of Esri’s ArcGIS Living Atlas data is provided as streaming services instead of download, but for an increasing number of workflows, this is actually perfect.  The Living Atlas has in a few short years become probably the largest collection of spatial data on the planet, and so I recommend keeping it in mind not just for satellite imagery, but vector data as well, some of which can be downloaded, and all of it can be streamed.  Plus, you can contribute your organization’s data to the Living Atlas.  On a related note, be sure to check ArcGIS Online for imagery as well, the web GIS platform that Esri’s ArcGIS Living Atlas is based on.

(4)  The Esri Landsat Thematic Bands Web Mapping Application.   As we described in this post, through this application, you can access a variety of up-to-date and historical images in various band combinations, and save specific configurations and locations to share with others.

(5)  The USGS Earth Explorer.  While the Earth Explorer is in my view in need of improvement from the user’s perspective, it is functional and does contain a wealth of data, and sometimes is the best source for specific image sets.

(6)  The USGS Landsat Look Viewer.  I prefer the Landsat Look viewer’s interface over the Earth Explorer, as I described here.

(7)  The USGS GloVIS viewer.  I also prefer this interface over Earth Explorer.  GloVIS dates back to 2001 and was redesigned in 2017.

(8)  Landsat 8 archive on Amazon AWS.  As we described here, this has emerged as an amazing archive of data.  The user, as one might expect, is faced with a list of files rather than a fancy User Interface, but sometimes accessing specific files is exactly what one needs.

(9)  Landsat archive in Google Cloud.   Like the AWS experience, the UI is spartan but its data sets are vast, which is what one would expect from Google.

(10)  The FAO GeoNetwork.  This site focuses on vector data sets, but its raster holdings include many useful Landsat mosaics for specific geographic areas such as countries.

(11) Remote Pixel.  This is incredibly easy to use and blazing fast to zoom, pan, and query, and largely the work of a single individual.  It is my hope that if its developer does not maintain it in the future, that someone else will, because it is so marvelous.  Fortunately, the developer shows others how to host something like this themselves.

(12)  The Copernicus Open Data Access Hub, as its name implies, focuses on Sentinel data, but if you are interested in Landsat imagery, you probably are interested in other imagery as well.

satellite_image_portals_collageA few of the image portals described in this article.   We look forward to your feedback!

–Joseph Kerski

Imagery: It is what it is: Well, not always.

May 12, 2019 2 comments

Being critical of all data, including geospatial data, is a chief theme of this blog and our book:  Use it wisely.  Know where it came from.  Know what has been done to it. Imagery has always been an important component of geospatial data, and today, it takes many forms, ranging from images taken on the ground with a phone or camera to those taken by webcams, UAVs, aircraft, satellites, and more.  Doesn’t this imagery “tell it like it is” and is it therefore exempt from us casting a critical eye on it?   I contend that no, images must be viewed critically so that you can determine if they are fit for your use in whatever project you are working on.

As one example in a larger story, consider the example of the removal of individuals from 20th Century photographs in the USSR. But lest we think such image doctoring was a thing of the past, there are dozens of articles that arise in current web searches highlighting modern day image manipulation, from fashion magazines to science journals, some inadvertent, some on purpose, some for purposes to benefit society and some unfortunately to mislead.  In the geospatial world, consider the image offsets on Google Maps in China that we wrote about not long ago.

Let’s discuss another aspect of image manipulation.  Consider the satellite images below.  They cover many different dates and are derived from many different sources.  But pay attention to what’s on–or off-the highways in the images.   These images all cover the same location—Interstate 30 – 35E interchange on the southwest side of downtown Dallas Texas USA, known locally as the Mixmaster.  Constructed between 1958 and 1962, you can spot, in some images, recent much-needed improvements due to the substantial increase in traffic volume in the past 60 years.

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Study area in ArcGIS Online (first image) and Mapquest (second image).

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Study area in Yahoo maps (first image) and Bing maps (second image).

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Study area in Google Maps (it appears the same way in Google Earth). 

Notice anything missing on the Google Maps image?  No traffic. This would be unheard of, day or night, in this busy part of one of the largest cities in the USA.  Obviously, a vehicle-removal algorithm has been applied to the image. It is actually quite impressive, because the algorithm seems to only be applied to moving vehicles–cars, buses, trains–and not to stationary vehicles.  No doubt it is applied to make the process of viewing and interpreting the now-clearer imagery easier.  Interestingly, the moving-vehicle removal seems to only, at the present time, be present in running Google Maps on the web on a tablet or laptop:  Running the Google Maps app on a smartphone shows moving vehicles (below).

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Study area in Google Maps app on smartphone. 

Key takeaway points and teachable moments here include:  (1) Images that can be obtained in web mapping services, in geodatabases, and portals should not be considered the same view that would be seen if someone were to be peering over the side of a UAV, airplane, spacecraft, or standing next to a webcam when the image was captured.  They can and are manipulated for a variety of purposes.   They need to be viewed critically.  At the same time, we can marvel and appreciate the many choices we have nowadays in imagery for use in geospatial analysis.   (2)  The machine learning and artificial intelligence techniques applied to imagery are further evidence for the enterprise nature of geotechnologies:  GIS is increasingly connected to mainstream IT trends and innovations.

–Joseph Kerski

 

Global Land Cover Facility goes offline

January 7, 2019 2 comments

The world of geospatial data portals is dynamic; new sites appear and others disappear.  Sites are shut down due to the end of a funding period, changes in technologies, or as a result of mission or personnel changes. One of the earliest and most useful sites particularly for remotely sensed imagery recently went off-line–the Global Land Cover Facility from the University of Maryland.  Their notice said, “The GLCF has had a very good run since 1997! Originally it was funded under NASA’s Earth Science Information Partnership (under the inspired leadership of Martha Maiden of NASA). Subsequently it was maintained to support our NASA-funded research activities especially those concerned with Landsat data.   We feel we have attained what we wanted to accomplish, and now it’s time for us to move on and explorer other ventures. The data and services provided by GLCF are now mostly available via government agencies, especially USGS and NASA.”

To expand on the last note above, what should you, the GIS user who loves imagery, do?  For the time being, the GLCF data are still on a no-graphics FTP site, here:  ftp://ftp.glcf.umd.edu/.   But better yet, we have examined numerous functioning imagery portals on this blog; start here.  These include, for example, LandViewer, EOS Data Analytics, NASA AVIRIS, the GeoPortal, Lidar from USGS, DevelopmentSeed, Sentinel-2, and many others.

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Thank you, GLCF!  You provided a wonderful service, and will be missed. 

–Joseph Kerski

Hangar: A new on-demand UAV Data Service

October 28, 2018 2 comments

We have written about the rapid evolution of imagery platforms and portals many times in these blog essays over the years.  One major recent advancement is the UAV service from Hangar, an Esri business partner.  This service allows data users to order UAV imagery and receive it according to their project specifications:
https://www.spar3d.com/news/uav-uas/hangar-esri-reality-data-arcgis/

In my way of thinking, it is sort of like an” Uber for Drones”.  Let’s say you don’t have a pilot’s license, or time, or equipment, or expertise to fly your own UAV imagery.  Hangar is a new UAV service covering all areas that may be of interest to a client requiring imagery.  For this service, Esri partners with Hangar, a company that holds hundreds of waivers to fly almost anywhere and the expertise and equipment to serve clients from just about any discipline and with any need.   For more information, read the article “Hangar Joins Esri Startup Program to Add ‘Task & Receive’ Aerial Insights ArcGIS:”   https://www.prweb.com/releases/2018/05/prweb15514744.htm. 

And two of the best examples of some of the Hangar imagery is this story map of the devastation from the Carr fire in California and this story map showing some of their imagery for Kilauea, shown below.   Be sure to zoom and pan the 360-degree UAV imagery shown in these story maps.  Warning!  They are highly addictive and fascinating.  And for those of us in education, they make for an attention-getting teaching tools which I have already used numerous times from primary school to university and beyond to teach about wildfires and volcanic hazards.

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-Joseph Kerski

Categories: Public Domain Data Tags: , ,

Historical Imagery for the entire world now available via Wayback Service in ArcGIS from Esri

July 5, 2018 2 comments

I know that many of you regularly want to examine changes-over-space-and-time with imagery and GIS for research or instruction purposes.   As of last week, 81 different dates of historical imagery for the past 5 years now reside in ArcGIS via the World Imagery Wayback service.   For more information, see: https://www.esri.com/arcgis-blog/products/arcgis-living-atlas/imagery/wayback-81-flavors-of-world-imagery/

You can access this imagery in ArcGIS Online, ArcMap, and ArcGIS Pro.  A great place to start is the World Imagery Wayback app – just by using a web browser  – https://livingatlas.arcgis.com/wayback/    A fascinating and an incredible resource for examining land use and land cover change, changes in water levels of reservoirs, coastal erosion, deforestation, regrowth, urbanization, and much more.  This resource covers the entire globe.

However, in keeping with the theme of our book The GIS Guide to Public Domain Data and this blog of being critical of the data, caution is needed.  The dates represent the update of the Esri World Imagery service.  This service is fed by multiple sources, private and public, from local and global sources.  Thus, the date does not mean that every location that you examine on the image is current as of that date.  I verified this in several locations where my ground observations in my local area show construction as of June 2018, for example, but that construction does not appear on the image.  In addition, several other places I examined from wintertime in the Northern Hemisphere were clearly “leaf-on” and taken during the summer before, or even from the summer before that.  Therefore, as always, know what you are working with.  Despite these cautions, the imagery still represents an amazing and useful resource.

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Sample from this imagery set for 30 July 2014 (top) and four years later, 27 June 2018 (bottom) for an area outside Denver, Colorado USA. 

Access data and analytical tools online from EOS Data Analytics

A new platform from EOS Data Analytics (https://eos.com/platform/) allows data users not only to access data, but even perform online image processing in a web browser.  It is a set of mutually integrated cloud products for searching, analyzing, storing, and visualizing geospatial data.  This is a representation of what we have been discussing on this blog, namely, the increasing adoption of Software as a Service, and in addition, the combination of SaaS with data services and analytical services.  Thus, GIS professionals can search for, analyze, store, and visualize large amounts of geospatial data in one platform.  Doing all this in one system and also in a browser is, quite frankly, quite amazing.

With the EOS Platform, GIS users have access to an ecosystem of four mutually integrated EOS products, which together provide a powerful toolset for geospatial analysts. Image data is stored in cloud-based storage and is available for image processing or remote sensing analysis at any time; this can be a raw user file, an imagery obtained from their LandViewer data portal, or an output file from their online EOS Processing tools.  The EOS Platform is currently available for free during an open Beta.   The LandViewer tool has been freely available for some time and will continue to be.

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There are at least two reasons why image processing is the platform’s major asset: the processing of large data amounts runs online and offers as many as 16 workflows with even more coming soon. On top of that, users can get the best cartographic features of EOS Vision for vector data visualization and soon to come, analysis.

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A list of EOS Processing workflows that can be filtered by industry and input data type.

I found the LandViewer tool easy to use, with a wide variety of data sets to choose from, including Landsat, MODIS, NAIP, and others.

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The LandViewer tool interface.

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Choosing one’s own area of interest via the LandViewer interface.