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2017

An increasing number of citizen science apps and projects are becoming geo-enabled:  That means that the data within these projects can be mapped and analyzed.  Furthermore, participating in these projects often contributes to a worthy global cause.  Mapillary is one such toolset and project.  It allows anyone to create their own street level photographs, map them, and share them via web GIS technology.  The idea behind Mapillary is a simple but powerful one:  Take photos of your campus or your community or another place of interest as you walk along using the Mapillary mobile app.  These photos will be combined into a street level photo view, which you can explore along with thousands of other places from users around the world.  Mapillary is helping local governments map their city's infrastructure, call attention to land use practices, and much more.  

 

A year ago, I described how you might use Mapillary as a viable part of your course's field component.  On the simplest level, you can use the Mapillary app and see your resulting track and photographs in the Mapillary mapping interface online.  More recently, I extended that with a discussion of how to bring a Mapillary track into ArcGIS Online for further mapping and analysis, with the resulting map shown here.   You can display any Mapillary data on an ArcGIS Online base map, such as my recent collected track, here.  Do this by appending "&mapStyle=esri" at the end of a Mapillary URL, such as this: "https://www.mapillary.com/app/?lat=20&lng=0&z=1.5&mapStyle=esri".   

 

Now, I want to extend my investigation and learning still further, by including my photographs into ArcGIS Online in addition to the track I brought in earlier.  I accomplished this, with the help of the Mapillary staff, as follows:  First, I created a ClientID, by registering an app, inputting my own data for the callback URL, website, app name, and other information, via https://www.mapillary.com/app/settings/developers.  Then, I ran another call to obtain the userkey for my account. I took the USERNAME and replaced it with my own, along with the CLIENTID generated in the first call, here: https://a.mapillary.com/v3/users/?usernames=USERNAME&client_id=CLIENTID.  The userkey was called "key" in the returned GeoJSON file, which I saved with a .geojson extension to my computer.  I also noted the userkey at this point.  Next, to obtain my tracks as line string data, I ran a third API call to search all sequences belonging to the user, replacing USERKEY and CLIENTID with my own userkey and clientid:  https://a.mapillary.com/v3/sequences?client_id=CLIENTID&userkeys=USERKEY.  This returned a second GeoJSON file, which I also saved with the extension .geojson for loading it later into ArcGIS Online.  I then ran one more call to obtain the images as point data:  https://a.mapillary.com/v3/images?client_id=CLIENTID&userkeys=USERKEY.  

 

One of the most exciting things about this is that my over 1,200 points all are linked to photographs that I took while in the field.  These photos are taken automatically with the Mapillary app each second or so--I did not have to touch "take photo" on my phone 1,200 times.  This ensured a safer experience and also an experience where I was free to observe my surroundings instead of concentrating on the technology, which is one of the things we are always encouraging in rich and meaningful field experiences.  The resulting experience in ArcGIS Online is a seamless hike up the trail, looking to each side, forward, and backward as I so chose while I was on my trek. 

 

Next, in ArcGIS Online, I used "Add Data" to add my two GeoJSON files.  I then configured a popup for the point layer. With each point, the image key is inserted into the URL, and a small image is generated in the popup that corresponds to the point where I took the photo.  The idea here is to let the photo key be a variable. The resulting map is linked here  and shown below.  I then ran a viewshed analysis on my track so I could determine the areas I could see from this beautiful trail that wound up into the chaparral hills of southern California.   

Mapillary Track with photographs in ArcGIS Online

 

And since my track is a feature layer I could now easily bring it into the 3D Scene Viewer, shown below and shared here  so you can interact with it. 

Mapillary Track with photographs in ArcGIS Online's 3D Scene Viewer

Mapillary is a business partner with Esri, and it is exciting to explore these and other new developments.  There is even a Mapillary for ArcGIS Online app, which allows you to view, create, and edit GIS data with the aid of Mapillary photographs.  To go still further, there is also a Mapillary web app builder template widget on GitHub, here.



Many web mapping applications provide an excellent teaching and research resource, because they are easy to use, quick to display, rich with data, and powerful.  One of the newest and most useful web mapping applications is the Landsat Lens.  The Landsat Lens is so named because it provides a "lens" of a series of Landsat images by year, by theme, and by region, selectable by the user.  In other words, it is the perfect tool to investigate changes over space and time.  Hence, it can be used in courses in geography, environmental science, hydrology, civil engineering, biology, GIS, and remote sensing, just to name a few.

 

Upon opening, the app shows a lens (Landsat image) dated 2017 located near the Palm Jebel Ali in Dubai.  A set of preset locations are available from the Bookmarks dropdown menu, or you can pan or zoom to any area of interest. For one of the preset locations, or for your own area of interest, you may want to view changes over time. To do so, use the Windows dropdown menu to add a window showing 2002, 2005, 2010, 2015 or 2017 imagery. By swiping lenses over the basemap and one another you can easily see changes from natural or human causes, in vegetation cover, agricultural expansion or contraction, urbanization, coastline erosion or modification, river dams or meanders, volcanic activity, or from other causes.  Use the last option in the dropdown menu to remove all lenses from the map.  You can also select themes such as Agriculture, Color Infrared, Natural Color, Moisture Index, or Vegetation Index, each of which focuses on specific bands in the electromagnetic spectrum to highlight these themes.  You can change the scale and even change the size of the "lenses" themselves.

 

Landsat Lens web mapping application

Landsat Lens web mapping application for an area southeast of Las Vegas, Nevada, USA.

 

For more information, see the blog post of my colleague who developed this amazing tool, his handy help file, and my video guiding you through some of this app's features.  Give Landsat Lens a try and I look forward to your comments below.

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