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Posts Tagged ‘imagery’

Enhancements to Landsat Thematic Bands Web Mapping Application

November 6, 2016 Leave a comment

Last year, we wrote about the Landsat Thematic Bands Web Mapping Application, an easy-to-use but powerful teaching and research tool and data set. It is a web mapping application with global coverage, with mapping services updated daily with new Landsat 8 scenes and access to selected bands that allows the user to visualize agriculture, rock formations, vegetation health, and more.  The Time tool allows for the examination of changes over years, over seasons, or before and after an event.  The identify tool gives a spectral profile about each scene.  I have used this application dozens of times over the past year in remote sensing, geography, GIS, and other courses and workshops, and judging from the thousands of views that this blog has seen, many others have done the same thing.

If that weren’t all, the development team at Esri has recently made the tool even better–one can now save a time sequence or a band combination as a permanent URL that can be shared with others.  The flooding of 20 districts in August and September 2016 in Uttar Pradesh, India, for example, can be easily seen on this link that uses the application, with screenshots below.

Another example is the Fort McMurray summer 2016 wildfire in Alberta, Canada  – the user can change the time to see the region’s vegetation cover before and after fire, and the extent of the smoke during the fire.  Or, you can analyze a different band combination, as is seen here.

To do this, open the application.  Note that the application URL has been updated from the one we wrote about last year.  Move to an area of interest.  Select any one of the available thematic band renderers (such as agriculture, natural color, color infrared, and others available), or create your own band combination using build.  Then, turn on “time” to see your area of interest at different periods using your band combination.  Next, share this image with other people.   Simply click on any one of the social platforms (Facebook or Twitter) in the upper right, which will create a short link that can be shared.  When the person you send this link to opens it, the Landsat app will open in exactly the same state it was in before social platform tool was clicked.  Give it a try!

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Landsat 8 Image for Allahabad India on 31 May 2016.

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Landsat Thematic Bands Web Mapping Application in ArcGIS Online

December 20, 2015 2 comments

Teaching remote sensing?  Or just want to understand remotely sensed imagery better?  The Landsat Thematic Bands web mapping application can serve as a very useful teaching, learning, and research tool.  It covers the entire planet and the map is updated daily with new Landsat 8 scenes.

You can access many band combinations and indices by hovering over the tools to the left of the map image and selecting among the following:

  • Agriculture: Highlights agriculture in bright green. Bands 6,5,2
  • Natural Color: Sharpened with 25m panchromatic band. Bands 4,3,2+8
  • Color Infrared: Healthy vegetation is bright red. Bands 5,4,3
  • SWIR (Short Wave Infrared): Highlights rock formations. Bands 7,6,4
  • Geology: Highlights geologic features. Bands 7,4,2
  • Bathymetric: Highlights underwater features. Bands 4,3,1
  • Panchromatic: Panchromatic image at 15m. Band 8
  • Vegetation Index: Normalized Difference Vegetation Index (NDVI). (Band5-Band4)/(Band5+Band4)
  • Moisture Index: Normalized Difference Moisture Index (NDMI). (Band5-Band6)/(Band5+Band6)

The Time tool for different indices at larger scales based on a user-selected location enables examination of changes over years or over seasons.  It also provides temporal profiles for NDVI (Normalized Difference Vegetation Index), NDMI (Normalized Difference Moisture Index) and an Urban Index, dating back to 1973.  The Identify tool enables access to information on the date, cloud cover, and a spectral profile about each scene.  The Bookmark tool allows access to interesting locations such as the “Eye of the Sahara” in Mauritania.

The application is written using Web AppBuilder for ArcGIS accessing image services using the ArcGIS API for JavaScript, with access to the following Image Services:

  • Landsat Multispectral on AWS – 8-band multispectral 30m resolution image services and functions that provide different band combinations and indices.
  • Landsat Pan-sharpened on AWS – Panchromatic-sharpened imagery; 4-band (Red, Green, Blue and NIR); 30m resolution.
  • Landsat Panchromatic on AWS – Panchromatic imagery; 15m resolution.

These services can also be accessed through the public Landsat on AWS group on ArcGIS Online.  Because you can add these services as layers to your own maps or are adding to maps made by others, or if you are simply using the above web mapping application as a standalone map, you truly have “the world at your fingertips” with these maps and apps.  But there is a third option: Use the Unlock Earth’s Secrets page, also useful for instruction, with the above application embedded in it, but also with explanatory text and featured places around the planet as they have changed through time.

Think of the above as solid introductory segments to help your students, customers, or stakeholders see the value in remote sensing.  These maps and applications require very little geospatial technology skills to use, but allow you to focus on building remote sensing concepts and principles while exploring some truly engaging content and places.

To dig deeper, delve into the many powerful remote sensing functions available in ArcGIS Desktop.  One source for engaging, hands-on activities, is Kathryn Keranen and Bob Kolvoord’s book Making Spatial Decisions Using GIS and Remote Sensing:  A Workbook.

Give these resources a try!

Landsat web application

Landsat web application in ArcGIS Online.

Sentinel-2 Imagery Now Available

December 14, 2015 1 comment

Earlier this year we wrote about the launch of the European Space Agency’s (ESA) Sentinel-2A satellite and the mission to deliver a range of data products including land cover maps and bio-geophysical data. ESA have just released the Sentinel-2A orthorectified products, which are now available to download for free from the Sentinel-2 Data Hub https://scihub.copernicus.eu/s2/.

Sentinel-2a Data Hub

Sentinel-2a Data Hub

ESA have also posted a data quality report to document the current status of the data and provide information on product formats and features. As the programme is currently in a ramp-up phase, further improvements in the extent of coverage and the accuracy of the products are expected over the next few months.

2015 and Beyond: Who will control the data?

November 17, 2015 1 comment

Earlier this year Michael F. Goodchild, Emeritus Professor of Geography at the University of California at Santa Barbara, shared some thoughts about current and future GIS-related developments in an article for ArcWatch. It was interesting to note the importance attached to the issues of privacy and the volume of personal information that is now routinely captured through our browsing habits and online activities.

Prof. Goodchild sees the privacy issue as essentially one of control; what control do we as individuals have over the data that are captured about us and how that data are used. For some the solution may be to create their own personal data stores and retreat from public forums on the Internet. For others, an increasing appreciation of the value of personal information to governments and corporations, may offer a way to reclaim some control over their data. The data could be sold or traded for access to services, a trend we also commented on in a previous post.

Turning next to big data, the associated issues were characterised as the three Vs:

  • Volume—Capture, management and analysis of unprecedented volumes of data
  • Variety—Multiple data sources to locate, access, search and retrieve data from
  • Velocity—Real-time or near real-time monitoring and data collection

Together the three Vs bring a new set of challenges for data analysts and new tools and techniques will be required to process and analyse the data. These tools will be required to not only better illustrate the patterns of current behaviour but to predict more accurately future events, such as extreme weather and the outbreak and the spread of infectious diseases, and socio-economic trends. In a recent post on GIS Lounge Zachary Romano described one such initiative from Orbital Insights,  a ‘geospatial big data’ company based in California. The company is developing deep learning processes that will recognise patterns of human behaviour in satellite imagery and cited the examples of the number of cars in a car park as an indicator of retail sales or the presence of shadows as an indicator of construction activity. As the author noted, ‘Applications of this analytical tool are theoretically endless‘.

Will these new tools use satellite imagery to track changes at the level of individual properties? Assuming potentially yes, the issue of control over personal data comes to the fore again, only this time most of us won’t know what satellites are watching us, which organisations or governments control those satellites and who is doing what with our data.

 

Spatial Agent: Highlighting Public Domain Datasets

October 19, 2015 1 comment

The World Bank recently announced the release of a new Spatial Agent app for iOS and Android (web version also available). The app curates an already impressive collection of public domain spatial datasets in a variety of formats from over 300 web services, with the developers promising to add more iconic datasets. App users can choose between the following data sources:

  • Indicators (for example % of female employees in agriculture or % of forested land areas)
  • Map layers
  • Other (for example the Nepalese major river system or hydro power plants in Malawi)

The data can be displayed against a back-drop of one of four base map sources:

  • Shaded relief (NOAA)
  • Street map
  • Topographic map
  • World imagery

with the option to set the area of interest by Country, Basin or Region.

In this example a layer of CIESIN’s earthquake hazard frequency and distribution data is displayed against a backdrop of world imagery.

Spatial Agent: Earthquake Hazards

Spatial Agent: Earthquake Hazards

Each dataset is accompanied by a short description of the source and intended purpose and as the datasets are public domain, they may be shared through email and/or social media.

The World Bank hope that the app will help spread the news about public domain data and go some way to organising the ‘current big data cosmos’.

 

 

 

 

 

 

 

 

Global Imagery Donation From Planet Labs

October 5, 2015 1 comment

Planet Labs, an US based imaging company that operates a constellation of miniature satellites, recently announced a new collaborative project with the United Nations and a number of private institutions and NGOs. The initiative, known as Open Region, will see the publication of $60 million worth of global imagery under a Creative Commons License Attribution-ShareAlike (CC-BY-SA) license.

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Planet Labs Color Images

The data will be available online through the Planet Labs imaging platform and accessed using web-based tools and/or an API for developers. The hope is easy and open access to the new data sets will provide a platform to help meet the UN’s Sustainable Development Goals, which include tackling climate change, promoting sustainable use of resources and eliminating poverty.

NASA’s New Data Portal

May 25, 2015 1 comment

NASA recently announced the launch of a new data portal, hosting a data catalog of publicly available terrestrial and space-based datasets, APIs and data visualisations.

NASA Data Portal

NASA Data Portal

NASA’s Open Innovation team has been established to meet government mandates to make their data publicly available. The datasets, posted in a number of categories including applied and earth science, will be available to download in a variety of formats although at present not all the formats are available for all of the categories. However the data portal is work in progress so worth checking back as new datasets are posted.

From a quick search for some earth science data I found a sea surface temperature dataset acquired by the Moderate Resolution Imaging Spectroradiometer (MODIS) instruments aboard NASA’s Terra and Aqua satellites that I could download in a number of image formats, Google Earth or CSV format. One feature of the data portal I found useful was the accompanying basic, intermediate or advanced dataset descriptions, helping portal users identify the right datasets for their requirements.

MODIS Sea Surface Temperature dataset

MODIS Sea Surface Temperature dataset