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3D imagery and aerial photography: Public access versus public safety and security

August 26, 2013 Leave a comment

One of the recurring themes in The GIS Guide to Public Domain Data is that of open access: How and when spatial data is made publicly available. A recent report from BBC reporter Zoe Lleinman, highlighted the continuing problem of balancing the public interest in access to detailed mapping data for towns and cites versus concerns from government organisations with respect to security and public safety. Officials from Norway’s National Security Authority have refused permission for Apple to take aerial photographs of the capital city Oslo to create a 3D imagery layer that would include government buildings and restricted areas. Although the data Apple require can be sourced elsewhere (for example, from the Norwegian Mapping Authority), the authorities felt they would have no control over how data would be used if Apple were to acquire the data themselves. Other map companies have used 2D satellite imagery, which is not protected, for their mapping services.

Maintaining public safety, and national security, has long since ceased to be simply a matter of security barriers and guard dogs patrolling the perimeters of restricted areas; with increasingly easy to use web mapping services, access to detailed spatial information no longer requires a physical presence at the site. Terrorist events in Norway, and the targeting of government buildings, triggered a major debate about security and public access to such information. We discussed a similar problem with attempts to ban access to Google Earth data in India following the attacks in Mumbai in 2008. As the Norwegian and Indian authorities themselves acknowledge, there are many benefits to be gained from having access to detailed imagery, but developing effective data access policies, where information use is monitored, is an on-going challenge.

Iowa Historical Imagery and other spatial data served in ArcGIS Online

August 4, 2013 Leave a comment

Some key spatial data from longstanding data portals are making their way onto platforms such as ArcGIS Online.  One of these is the data from the Iowa Geographic Map Server, served from the Iowa State University GIS facility.  The data set, searchable on ArcGIS Online via the keywords “Iowa Geographic“, is one of the finest examples of the holdings of a state data depository in an easy-to-use format.

Iowa State GIS Data in ArcGIS Online

Iowa State GIS Data in ArcGIS Online.

The data available includes aerial photographs from the 1930s, 1950s, and then every decade from the 1970s onwards.  Also included are an atlas from 1875, a general land office survey from the 1800s, a hillshade from Lidar data, the public land survey system, civil townships, and watershed boundaries.  Changes in agricultural practice, urban forms and size, river meanders, and much more can be explored via this map.  In addition, one can add the individual layers to one’s own map by pointing to the server URL found in the metadata for each layer.  That the metadata are well populated is another reason that the data portal has long been one of my favorites.  If one needs to download the data, those data sets are still available via the data portal at Iowa State University on http://ortho.gis.iastate.edu/.   While even more data are available via the data portal itself at Iowa State University, it is wonderful to be able to quickly browse a subset of the data via the ArcGIS Online map.  ArcGIS Online contains tools such as making layers transparent, adding map notes and bookmarks, and the ability to use the Iowa portal layers as a backdrop for one’s own data.  In addition, as a teaching and research tool, the way the data are served in ArcGIS Online allows land use changes to be quickly observed and measured without having to download each layer and loading them into desktop GIS software.

As data from portals such as the Iowa Geographic Map Server migrate to platforms such as ArcGIS Online, the data user will have additional ways to access that data.  It takes a commitment from data providers to serve their holdings onto these platforms, but data users in government, nonprofit, industry, and academia will all benefit.  Learn more about data portals, data platforms such as ArcGIS Online, and data types in our book The GIS Guide to Public Domain Data, and keep an eye on this blog. 

New Digital Globe Imagery in ArcGIS Online

January 2, 2013 1 comment

In chapter 3 of our book The GIS Guide to Public Domain Datawe discuss the increasing resolution, types, and ways to access sources of imagery and the  implications of these changes for data users.  Last week, imagery and for the continental United States and 60cm imagery for large parts of Western Europe arrived on the ArcGIS Online platform.

According to the announcement, http://blogs.esri.com/esri/arcgis/2012/12/20/digitalglobe-imagery-for-the-united-states-and-western-europe-added-to-the-world-imagery-map/, this is the first of several planned releases of new imagery from DigitalGlobe that will include Europe and many other parts of the world.

Another very useful feature is that with the Identify tool in ArcMap or the ArcGIS Online Content Viewer, or even inside the ArcGIS Online map viewer, the resolution, collection date, and source of the imagery can be obtained at the location on which you click.  The metadata applies only to the best available imagery at that location. You may need to zoom in to view the best available imagery.   The service was updated on the following servers: services.arcgisonline.com and server.arcgisonline.com.  If you have previously used the World Imagery map, you may need to clear your cache in order to see the updates.  For example, in the area in which I am examining in San Francisco, the popup indicates that the imagery is from 26 October 2010 and is at 30 cm resolution.

30 cm Digital Globe imagery in ArcGIS Online

30 cm Digital Globe imagery in ArcGIS Online

10 New ArcGIS Pro Lesson Activities, Learn Paths, and Migration Reflections

May 14, 2020 3 comments

A new set of 10 ArcGIS Pro lessons empowers GIS practitioners, instructors, and students with essential skills to find, acquire, format, and analyze public domain spatial data to make decisions.  Described in this video, this set was created for 3 reasons:  (1) to provide a set of analytical lessons that can be immediately used, (2) to update the original 10 lessons created by my colleague Jill Clark and I to provide a practical component to our Esri Press book The GIS Guide to Public Domain Dataand (3) to demonstrate how ArcGIS Desktop (ArcMap) lessons can be converted to Pro and to reflect upon that process.  The activities can be found here.  This essay is mirrored on the Esri GeoNet education blog and the reflections are below and in this video.

Summary of Lessons:

  • Can be used in full, in part, or modified to suit your own needs.
  • 10 lessons.
  • 64 work packages.  A “work package” is a set of tasks focused on solving a specific problem.
  • 370 guided steps.
  • 29 to 42 hours of hands-on immersion.
  • Over 600 pages of content.
  • 100 skills are fostered, covering GIS tools and methods, working with data, and communication.
  • 40 data sources are used, covering 85 different data layers.
  • Themes covered: climate, business, population, fire, floods, hurricanes, land use, sustainability, ecotourism, invasive species, oil spills, volcanoes, earthquakes, agriculture.
  • Areas covered:  The Globe, and also:  Brazil, New Zealand, the Great Lakes of the USA, Canada, the Gulf of Mexico, Iceland, the Caribbean Sea, Kenya, Orange County California, Nebraska, Colorado, and Texas USA.
  • Aimed at university-level graduate and university or community college undergraduate student.  Some GIS experience is very helpful, though not absolutely required.  Still, my advice is not to use these lessons for students’ first exposure to GIS, but rather, in an intermediate or advanced setting.

Why use these lessons?  The lessons offer 8 unique advantages:  (1)  The lessons engage students by focusing on the geographic inquiry processbeginning with the problem to be solved, such as the optimal site for siting a new business in a metropolitan area, the rate and pattern of the spread of an invasive species, the ideal locations for growing tea in Kenya, assessing reservoir and dam vulnerability in the event of a hurricane, and more.

(2)  While those working through the lessons build solid GIS skills (building expressions, joining data layers, intersecting, projecting, georegistering imagery), skills are not limited to “learning more GIS.  Skills in data management and communication are a prominent part of these lessons.  At the end of each lesson, students are asked to communicate the results of their research in a variety of ways, including sharing to ArcGIS Online, making a short video, and creating a web mapping application such as a story map.

(3) A significant proportion of each lesson touch on accessing, formatting, projecting; i.e. developing data competencies.  Helping people make wise decisions about the data, and giving them practical skills in doing so, is one of our chief goals with these lessons and the book.  A balance is struck between engaging with enough data to provide a realistic scenario, but recognizing that “more is not always better.”

(4)  The same lesson is available in an ArcGIS Desktop (ArcMap) format and an ArcGIS Pro format, so that those still hesitating about migrating from ArcGIS Desktop to ArcGIS Pro can use these as an example that it is not only possible, but there are many advantages to doing so.

(5)  Questions posed in each lesson focus on thoughtful reflection about the data and the process, such as, “what difference would data at a different scale have on your analysis results?”, “what was the most significant thing you learned about natural hazards in this lesson?” and “if you had more time, what data set might you have also wanted to include in your analysis?  Where do you think you could obtain such data?”

(6) These lessons have been tested and refined over several terms with students across many universities.

(7) An answer key is available for each lesson.   But in keeping with the reflective nature of these lessons, often, there is no “single correct answer.”

(8)  A lesson on building an ecotourism map in New Zealand allows students to use their gained skills in an independent project where they decide what themes to choose, what data to use, how to process it, and what problems to solve.

How to access the lessons:   The ideal way to work through the lessons is in a Learn Path which bundle the readings of the book’s chapters, selected blog essays, and the hands-on activities..  The Learn Path is split into 3 parts, as follows:

Solving Problems with GIS and public domain geospatial data 1 of 3:  Learn how to find, evaluate, and analyze data to solve location-based problems through this set of 10 chapters and short essay readings, and 10 hands-on lessons:  https://learn.arcgis.com/en/paths/the-gis-guide-to-public-domain-data-learn-path/

Solving Problems with GIS and public domain geospatial data 2 of 3:   https://learn.arcgis.com/en/paths/the-gis-guide-to-public-domain-data-learn-path-2/

Solving Problems with GIS and public domain geospatial data 3 of 3:   https://learn.arcgis.com/en/paths/the-gis-guide-to-public-domain-data-learn-path-3/

The Learn Paths allow for content to be worked through in sequence, as shown below:

 

pdd_learn_path1pdd_learn_path2pdd_learn_path3

Sample Learn Path for the public domain data activities.

You can also access the lessons by accessing this gallery in ArcGIS Online, shown below.  If you would like to modify the lessons for your own use, feel free!  This is why the lessons have been provided in a zipped bundle as PDF files here and as MS Word DOCX files here.    This video provides an overview.

pdd_gallery

Appearance of content items in the public domain data activities and reading gallery.  The gallery includes lessons, data, readings, and the answer keys. 

While the intent is for learners to actually download or stream the data from the original sources as an important part of the learning experience, the data for each lesson in zip file format are also included, in this ArcGIS Online gallery.  The reason the data is provided is because we recognize that sometimes, bandwidth is limited and/or the data portals are slow, change, or are temporarily offline.

Titles of the 10 Lessons:   See below.  For more information, see the detailed metadata for the lessons here.
Lesson 1: Assessing impacts of climate change on coasts, ecoregions, and population globally.
Lesson 2: Siting an internet café in Orange County, California.
Lesson 3: Siting a fire tower in the Loess Hills, Nebraska.
Lesson 4: Analyzing floods and floodplains along the Front Range, Colorado.
Lesson 5: Assessing potential hurricane hazards in Texas.
Lesson 6: Analyzing land use and sustainability in Brazil.
Lesson 7: Creating a map for an ecotourism company in New Zealand.

Lesson 8: Assessing citizen science portals and analyzing data about invasive species.
Lesson 9: Investigating 3 hazards: Gulf oil spill, Eyjafjallajokull volcano, and Haiti earthquake.
Lesson 10: Selecting the most suitable locations for tea cultivation in Kenya.

The intent of the lessons was that they were to be used in conjunction with reading the book.  Therefore, the contents of the book have also been placed online.  The book chapters are in this gallery. The book not only discusses sources and types of spatial data, but also issues such as assessing data quality, open data access, spatial law, the fee vs. free debate, data and national security, the efficacy of spatial data infrastructures, and the impact of cloud computing and the emergence of GIS as a Software-as-a-Service (SaaS) model.

Since the book was published, ongoing social and technological innovations and issues continue to change how data users and data providers work with geospatial information to help address a diverse range of social, economic and environmental needs.  Therefore, we established the Spatial Reserves blog to promote a current, ongoing dialogue with data users and providers and post frequent assessments of new tools, data portals, books and articles, curriculum, and issues surrounding spatial data.  Recent entries include “Imagery–It is what it is–well, not always.”, “Be a wise consumer of fun posts, too“, “The Application for Extracting and Exploring Analysis Ready Samples (AppEEARS)”, reflections on a new article about the geospatial data fabricfacial recognition technology, and a list of the top 12 sites for Landsat data.  A selection of these blog essays are listed in the book’s resources page at Esri Press.

Reflections on Migrating Lessons from ArcMap to ArcGIS Pro.  Readers of this blog and the GeoNet education blog are familiar with the rapid change of the field of geospatial technologies, coupled with rapidly changing educational and workplace needs.  I contend that given these changes, the content and skills we must teach, and the means by which we teach, must also change.  Given the wide variety of tutorials and help files containing graphics and videos, networks and the tools to collaborate, ask questions, and share ideas, students, faculty, and GIS professionals have an amazing variety of learning options at their fingertips.

Thus, I do not believe we need to be focused on tool-based approaches, such as how to geocode, how to georegister, and so on, but rather, how to solve problems using GIS.  (For a related discussion, see David DiBiase’s Stop Teaching GIS essay).  We need to help students “learn how to learn” whether in GIS (and, I contend, in any other field), emulating the kind of resource gathering, networking, and problem solving that they will assuredly use in the workplace.  Some might argue that writing and asking students to go through lessons such as the 10 I describe above is no longer needed.  In my experience in teaching for over 25 years at the university level, I still find that this style of lesson still has a place in learning, as students using these go through an entire workflow of geographic inquiry, including asking geographic questions, gathering data, analyzing data, making decisions, making assessments, and communicating the results of their research.  Another reason why I created the above lessons is so that you can place each lesson side-by-side to compare the ArcMap version and the ArcGIS Pro version.

My observations after creating ArcGIS Pro versions of each of the ArcMap lessons are as follows:

  1. I have used these lessons in several different universities, including at the University of Denver, and always pose a survey question about ArcGIS Pro at the end of the course.  In 95% of the responses, students have stated that they found ArcGIS Pro to be easier to learn from than ArcMap, more intuitive, and more powerful.  Several students each term tell me that the use of Pro was one of their primary reasons for taking the course, because their employer asked them to learn it.  And moving forward into the 2020s, Pro will see further adoption and more importantly, further evolution. Every time it evolves, it becomes more powerful and easier to use at the same time.
  2. As an instructor, you have a choice of either creating your own lessons or using existing lessons.  There are no shortage of existing lessons, ranging from the ArcGIS Learn library to shared higher education resources (such as GeoTech Center and iGETT), Esri and university MOOCs, and many other resources.  Many of us, however, became instructors because we enjoy creating and customizing curriculum for specific courses and programs.  If you are keen on migrating some of your existing ArcMap lessons to ArcGIS Pro, I did it, and so can you.  Yes, it will take some time, but I find migrations (migrations is plural here, as I have lived through many such software migrations!) are like when you get rid of things while moving your own residence–it is a good opportunity to purge old content and make things even better.  Perhaps you can get a graduate student to assist you in this effort!
  3. I found that my ArcGIS Pro lessons were shorter than the ArcMap lessons for several reasons.  The first reason is that the workflows in ArcGIS Pro are so much more logical and straightforward than in ArcMap.  In ArcMap, for example, when you needed to georegister an unprojected historical map or aerial photo, you are cast into a zone that sometimes left students wondering, “what step do I do first?” whereas with ArcGIS Pro, you are placed into wizard-driven “Step 1–do this, make these choices, satisfied?  If not, here are some adjustments you can make.  OK – on to Step 2…”  Ditto for hundreds of other tools and processes:  These are much easier to follow and learn from using ArcGIS Pro. The second reason is you don’t need to screen shot everything any longer, and in fact, I implore you to please not screen shot very much, because (1) There are many good existing resources for use if a student gets stuck on a certain section.  In the past, I admit that all of us did have to create our own graphics and screenshots because these were by and large all the students could use as instructional resources, but no longer!  (2) Students, being the resourceful people they are, will not read your precious screen shots very much if at all.  They know there are other resources and will find them if they have difficulty.  Of course you can provide guidance as to where these resources are, but just like anything else these days that people want to learn, such as fixing a faucet or playing the ukulele, there is a video, a graphic, a tutorial, on everything from geocoding to writing Arcade expressions and more.  (3) If you do screen shot to excess and make your lessons consequently long, you will remain in a continuous cycle of having to update and curate your lessons.  Please, don’t do this!  Rather, spend less time updating curriculum, and that new-found time creating new curricular ideas, teaching techniques, and furthering your own research.

Metadata for Public Domain Data Lessons

Metadata for Public Domain Data lessons.  I look forward to your comments below.

–Joseph Kerski

Download Arctic area digital elevation data from ArcticDEM

December 22, 2019 Leave a comment

Here we are at the winter solstice in the Northern Hemisphere and it seems appropriate to discuss polar data.  ArcticDEM is an NGA (National Geospatial Intelligence Agency) – NSF (National Science Foundation) public-private initiative to produce a high-resolution (2 meter), high quality, digital surface model (DSM) of the Arctic using optical stereo imagery, high-performance computing, and open source photogrammetry software.  The majority of ArcticDEM data was generated from the panchromatic bands of the WorldView-1, WorldView-2, and WorldView-3 satellites. A small percentage of data was also generated from the GeoEye-1 satellite sensor.  The resource covers all land north of 60 degrees north latitude.  Yes!  Not only Alaska, but Scandinavia, Russia, Canada and Iceland.  For more information, see this page.  For a web mapping application the Arctic DEM Explorer from Esri, see this page, and for the bare-bones but useful file index for fast downloading, see this page.

In my opinion, the most useful site about Arctic DEM for downloading the data is this web mapping application, the ArcticDEM index and data download.  This application allows a user to select specific index tiles of digital elevation model data.  The tiles reveal information about the DEM tile and a download web URL.  Each cell is about 2GB, with over 18 TB on the entire site.  Truly a treasure trove of data!  For selecting multiple indices, use the ‘Query’ tool to draw an area and return information on intersecting DEM tile indices. You can export these results for your reference which also include the download web URLs.

Click on any location for attribute information.  Find the “fileurl” attribute, click on More info, and then you will be able to download the 2 meter elevation data for that location.  The query widget allows for the retrieval of information from source data by executing an intersect query either against 2m DEM strips or 2M DEM mosaics.   The resource also includes a swipe tool where you can compare the content of two different layers on the map, such as the index layer and the hillshade.

The best news about this resource, and consistent with our continued mantra about GIS as a SaaS, may be that the site allows for the data to be examined as an ArcGIS Online item and also as an image service via a URL.

arcticdem.PNG

Interface of the Arctic DEM Index and Data Download resource. 

arcticdem2.PNG

The Arctic DEM data streamed and viewed in ArcGIS Online. 

I look forward to hearing your reactions to this resource.

–Joseph Kerski

Application for Extracting and Exploring Analysis Ready Samples (AρρEEARS)

November 24, 2019 Leave a comment

Imagine a data site where you can upload your own data for processing and spatial analysis, using tools that you do not own!  The Application for Extracting and Exploring Analysis Ready Samples (AρρEEARS) allows you to do just that.  I recently attended a presentation about this application at the Applied Geography Conference on AppEEARS and was very impressed.  AppEEARS offers a simple, efficient way to access and transform geospatial data from a variety of federal data archives, and hence merits highlighting in this Spatial Reserves data blog. AppEEARS enables data users to subset and extract geospatial datasets using spatial, temporal, and band/layer parameters.

Two types of sample requests are available: point samples for geographic coordinates and area samples for spatial areas via vector polygons.  Results stay on the LP DAAC site for 30 days, during which time you can archive them somewhere else or download them to your own device or server.

You need to have an Earthdata free account to use the site, but once you get one here, you can be off and running.  AppEEARS is tied to the LP DAAC (Land Processes Distributed Active Archive Center), in which there is no shortage of data.  Sample requests submitted to AρρEEARS provide users not only with data values, but also associated quality data values. Interactive visualizations with summary statistics are provided for each sample within the application, which allow users to preview and interact with their samples before downloading their data.

What’s more, you can also access the AρρEEARS API. This API allows users to write programs to interact with AρρEEARS. This is largely the same API that powers the AρρEEARS user interface.

My favorite part of AppEEARS is the tutorials and lessons that are in the e-learning resources zone, here.   Presentations, videos, and webinars are housed there, but my favorite part is the tutorials.  These are detailed, clear, and can be used as self-contained lessons for you, your colleagues, or students to learn about analysis methods, spatial data, and earth phenomena such as wildfires.  For example, using a tutorial written by Danielle Golon from Innovate Inc (a USGS contractor), you can generate remote sensing-derived environmental descriptors to monitor Yosemite National Park, without downloading the remotely sensed data itself:  All of your processing is done on the AppEEARS site, and you will use imagery, box plots, whisker plots of NDVI values, and other tools and data to analyze several fires from 2013 to 2018 over space and time.   You will use NASA Visible Infrared Imaging Radiometer Suite data (VIIRS) and MODIS data (Moderate Resolution Imaging Spectroradiometer).

Using another tutorial, you will generate environmental descriptors of bus stops in the Phoenix metro area to determine which bus stops could benefit from heat relief shelters.  This tutorial uses MODIS data and daily surface weather data.

 

appears-output.PNG

Sample AppEEARS temporal data for fire analysis.  

I highly recommend giving the AppEEARS resources and tools a try.

–Joseph Kerski

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

Verifying location data with blockchain cryptography

May 20, 2019 1 comment

Following on from Joseph’s recent post on some of the issues associated with the plethora of image resources we now have access to, another interesting aspect of verifying those data sources relates to the basic premise of proof. How can a data provider, whether that’s an individual or global company, prove the data they collect and publish are an authoritative and accurate representation of the locations they seek to record? The problems associated with Geolocation and GPS Spoofing are not new, with many protocols and procedures now in place to help prevent this type of deception. Conversely, GPS simulators are generally available, making it relatively easy for location hackers to interfere with GPS signals.

So how do data providers prove entities, in both the physical and human-made environments, really do exist at a particular location? One company, XYO, has been working on an alternative to satellite networks as a source of verified location information – the XYO Network. By augmenting our increasingly interconnected network of digital devices with location tracking technologies that incorporate blockchain cryptography, these co-opted devices (acting as sentinels or bridges) can be configured to recognise, validate and confirm the location of each other. As each device acts as a witness to the location of other devices; the more witnesses there are confirming a device’s location, the less chance there is that location is incorrect. The end result is a decentralised location data network that is arguably at less risk of being compromised.

Bound witnesses (sentinel and bridge devices) in San Francisco – https://matrix.xyo.network/map

Using device networks in this manner is an interesting new development in evolution of geospatial data and an emerging technology to watch.