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Posts Tagged ‘remote sensing’

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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Harmonising UAS Regulations and Standards: Article Review

October 23, 2016 Leave a comment

A recent article in GIM International about harmonising UAS (Unmanned Aerial Systems, or UAVs (Unmanned Aerial Vehicles), or “Drone” technologies) regulations and standards is definitely worth reading, providing an excellent summary of this rapidly evolving sector of the geospatial industry.  The article, beginning on page 6, is in a special issue of GIM International dedicated exclusively to UAS, available here.  Peter van Blyenburgh summarizes developments in regulations and standardization in Europe, the USA, Japan, and China, and then provides some down-to-earth advice for companies who are seeing the potential for profits only but may not see the bigger picture about liability, regulations, and safety.  The GIM issue also includes articles about integrating UAS and multibeam echosounder data, multispectral and thermal sensors on UAVs, UAS applications in agriculture, and the article “Airborne laser scanning” provides an excellent introduction to the two main platforms:  fixed-wing and rotorcraft.

If I am reading the “tea leaves” correctly, in the world of education, just about every GIS program offered at a technical college and university will include at least one course in UAS technology and data by this time next year.  And I would expect that a whole host of online MOOCs and other courses will appear from universities, companies, and GIS organizations to help people effectively use these new tools and technologies.  I attended, for example, a multi-hour course at the recent Geo’Ed community college GIS conference on this topic.  This reinforced my opinion that while online courses and programs will be helpful, the face-to-face component, actually working with the software and hardware, is particularly useful when working with UAS:  There is no perfect substitute for rolling up one’s sleeves and working with these devices.

As publishing director Durk Haarsma states in his editorial for this special issue, UASs are disruptive technologies, because they are influencing so many geospatial fields and subfields, such as cadastral surveying, cultural heritage, and precision agriculture, just to name a few.  Because UAS influence how people in an increasing number of professions map and model the world, interpreting the data from those UAS is central to our book and this blog–understanding your data, and how they are obtained, is more critical than ever.

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Launching a fixed wing UAV at the Geo’Ed conference, Louisville Technical College, Kentucky. Photograph by Joseph Kerski.  Video here and analyzing thermal imagery here.

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.

Landsat 8 Data Now Available on Amazon AWS

April 13, 2015 Leave a comment

Last month Amazon announced the release of Landsat 8 data on its AWS S3 platform. The data are freely available in GeoTiff format and are not subject to any restrictions on use. The imagery is updated on a 16 day cycle and is available on AWS within hours of reception by USGS.

All of the scenes from 2015 are available, along with a selection of scenes from 2013 and 2014. For those interested in downloading the data (no Amazon account required), each scene’s directory includes the following:

  • a .TIF GeoTIFF for each of the scene’s up to 12 bands
  • .TIF.ovr overview file for each .TIF
  • a _MTL.txt metadata file
  • a small rgb preview jpeg, 3 percent of the original size
  • a larger rgb preview jpeg, 15 percent of the original size
  • an index.html file including the RGB preview and links to the GeoTIFFs and metadata files

As a partner in the initiative to provide easier access to the imagery, Esri has created a set of Landsat Web Services that are available through ArcGIS Online. The services provide dynamic access to the entire collection of Landsat 8 data on AWS.  The web services show one Landsat 8 service that has a subset of the Landsat 8 imagery. If you are interested in downloading more, see the “downloading” link  here.

Cambridge Gulf in Australia

Cambridge Gulf in Australia

 

 

 

UAVs Prohibited in National Parks in the USA

November 10, 2014 2 comments

As we state in our book, The GIS Guide to Public Domain Data, oftentimes, technological advancement and adoption proceeds at a faster pace than regulations accompanying it.  A perfect example is what is probably the hottest technology in remote sensing right now, and that is UAVs, or Unmanned Aerial Vehicles.  The Internet is becoming rapidly filled with stories and videos of footage from UAVs deployed by aerial survey companies, but even more commonly, operated by the general public.  For example, this storymap contains footage of UAV imagery flown over a rocket launch, a cruise ship, and more.

While I as a geographer are fascinated by these images and videos, I am at the same time sensitive to the myriad of privacy and safety issues raised by the operation of UAVs.  We are beginning to see laws passed to regulate the operation of UAVs on certain lands, such as the recent policy directive against flying these in national parks in the USA.

Jonathan Jarvis, director of the National Park Service, said that “We embrace many activities in national parks because they enhance visitor experiences with the iconic natural, historic and cultural landscapes in our care.  However, we have serious concerns about the negative impact that flying unmanned aircraft is having in parks, so we are prohibiting their use until we can determine the most appropriate policy that will protect park resources and provide all visitors with a rich experience.”  Some parks had already initiated bans after noise and nuisance complaints from park visitors, an incident in which park wildlife were harassed, and park visitor safety concerns.  For example, earlier this year, visitors at Grand Canyon National Park gathered for a quiet sunset were interrupted by a loud unmanned aircraft flying back and forth and eventually crashing in the canyon. Volunteers at Zion National Park witnessed an unmanned aircraft disturb a herd of bighorn sheep, reportedly separating adults from young animals.

The policy memorandum directs park superintendents to take a number of steps to exclude unmanned aircraft from national parks. The steps include drafting a written justification for the action, ensuring compliance with applicable laws, and providing public notice of the action.  The memorandum does not affect the primary jurisdiction of the Federal Aviation Administration over the National Airspace System.

The policy memorandum is a temporary measure, and it seems like a wise move. Jarvis said the next step will be to propose a Servicewide regulation regarding unmanned aircraft. That process can take considerable time, depending on the complexity of the rule, and includes public notice of the proposed regulation and opportunity for public comment.  The National Park Service may use unmanned aircraft for administrative purposes such as search and rescue, fire operations and scientific study. These uses must also be approved by the associate director for Visitor and Resource Protection.

Near the Esri office in Colorado a month ago, I witnessed my first UAV flight where I did not know who was operating the vehicle.  I’m sure we will look back in years to come and realize that we in 2014 were at the dawn of a technology that will no doubt transform GIS and our everyday lives.   I anticipate sensors soon capable of capturing imagery in a wide variety of wavelengths, as well as atmospheric and other types of sensors that will further hasten the era of big data.  I am hopeful that we will chart a prudent course through the advent of UAVs, taking advantage of the innumerable benefits that UAVs can offer the GIS industry and also society as a whole.

Inexpensive and crowdsourced remote sensing

September 1, 2013 3 comments

In an article entitled “The Watchers”, David Samuels discusses a company seeking to deploy small satellites into orbit 500 miles (805 km) above the Earth.  This company, Skybox, founded by ex-Stanford University students, seeks to shake up the commercial space imaging industry by doing two things:  (1) Deploying smaller, less expensive satellites than what the commercial space imaging industry is currently using, the size of a dormitory room refrigerator, and (2) Using crowdsourcing for data classification.  They seek to have ordinary citizens classify the incoming data, as well as do some classification themselves, even from images that the company has collected but does not sell.  This could be the number of cars in every WalMart parking lot in the USA, the size of slag heaps outside the world’s largest gold mines in South Africa, and the rate at which the wattage along key stretches of the Ganges River is growing.  These bits of information, they reason, are clues about the economic health of countries, industries, and individual businesses.  Therefore, this information will be so valuable to investors, environmentalists, activists, and journalists, to name a few, that they will be willing to pay for the information.  The company is working with the government of Russia for a launch vehicle and hopes to launch its first satellite this month, SkySat-1.

The future: More cameras overhead?

The future: More cameras overhead?  Photograph by Joseph Kerski.

This story connects well with issues we raise in the book The GIS Guide to Public Domain Data, including data quality and resolution, military vs. civilian uses of data, crowdsourcing, and privacy. The resolution of the images returned from Skybox’s satellites will be comparable–less than 1 meter–to those from large commercial satellite imaging companies such as Digital Globe.  However, the cost of constructing them should be considerably less and the size of the satellite itself considerably smaller.  Skybox has added numerous advisers with connections in the defense industry “to avoid any military-industrial squelching of its technology before launch.”  Relying on crowdsourcing to classify images is not a new concept, but what is new here is the scale at which it could be employed, and that it is embedded in the company’s business model.  How standards will be established to assure data quality to potential purchasers of the derived information will be very interesting indeed.  Lastly, the idea of inexpensive, high resolution, easy-to-deploy satellites imaging the planet has enormous privacy implications for those of us on the ground, whether from Skybox or for others who are sure to follow.