1. Think about all the jobs that satellites are doing—communication, TV transmission, weather monitoring, military applications, GPS, and remote sensing. When you consider how useful these tasks are, you can see why we have many, many satellites in orbit. To get started looking at the orbital paths of satellites, go to https://www.n2yo.com, which is the Website for a tracking app for satellites. When you go to this site, you see the current location of the International Space Station (ISS) plotted on a map, but you can use the site to track the paths of a multitude of different remote sensing
satellites. From the Satellites on orbit pull-down menu, choose MORE CATEGORIES and then click Earth resources. A new list of satellites appears, and you can sort them alphabetically by clicking on the Name column head. If you click on the name of a satellite, a new Web page appears, providing information about the satellite as well as a map of its current location and when the satellite will next be in orbit over your current location.
Expansion Questions
► What is the current position of the following remote sensing satellites: Landsat 7, Landsat 8, Sentinel-2A, Sentinel-2B, and SPOT 7?
► When will each of the five satellites whose current position you found next pass over your current location?
2.The USGS has a second utility for viewing and downloading Landsat imagery: the LandsatLook Viewer, available at https://landsatlook.usgs.gov/viewer.html. To begin using it, from the set of tools in the upper-left corner, choose the magnifying glass (the search tool), and a search box opens. Enter the name of the area for which you want to view Landsat imagery, and LandsatLook Viewer zooms to that location. A pop-up window allows you to select imagery years, months, and percentage of cloud cover and to also select the sensors you wish to see for imagery (such as Landsat 7 ETM+ and Landsat 8 OLI). If you click on Show Images, LandsatLook shows you the available Landsat imagery for that location, along with a grid denoting the path and row of the available scene. In the pop-up window, you can slide the bar to view imagery of a specific date or use the arrows to move between images. You can also adjust the transparency of the Landsat images to see how they match up with the base map.
Expansion Questions
► In what path and row is your local area located? What Landsat imagery is available via LandsatLook Viewer for that path/row combination for last month?
► How many Landsat images are available for your local area through LandsatLook Viewer? Are there any large-scale land-cover changes that you can see over time by viewing imagery from past and current years for your local area?
3.Earth Observatory (at http://earthobservatory.nasa.gov) is a NASA Website devoted to global environmental and climate issues and how satellite remote sensing contributes to our understanding of those issues. Think of it as a sort of online “magazine” with articles and imagery from 1998 to the present. Earth Observatory features the “Image of the Day” section (accessible under the Images tab), which highlights a different satellite image concerning a climate or environmental topic each day.
Also, under the Articles tab, NASA posts information about climate and environment monitoring based on current events. Under the Topics section, a sidebar opens to allow you to browse imagery by topic (such as Atmosphere, Water, or Human) as well as view topics in the archive going back to 1998.
Expansion Questions
► To what kinds of climate and environment phenomena are the most recent “Image of the Day” images dedicated? Which satellites and sensors are being used to observe and monitor them? ► What kinds of environmental changes have been monitored by your selected topic of interest
under the Topics heading, and how has satellite imagery been applied to this study and analysis?
4.NASA Worldview is a Web application that allows you to view recently acquired imagery from several different Earth-observing satellites and their sensors, including MODIS. Open your Web browser and go to https://worldview.earthdata.nasa.gov.
From the Layers panel on the left-hand side of the screen, you can select the type of imagery you want to examine; for instance, one of the default options is Corrected Reflectance (True Color) MODIS imagery. By clicking on the Events tab, you can examine specific occurrences (such as volcanoes, fires, or tropical storms) that were imaged by sensors such as MODIS.
After you’ve selected a type of imagery or a specific event, click the Camera icon at the bottom of the screen (to the left of the timeline) to set up and then play an animation of imagery. NASA Worldview shows you a different remotely sensed image for each date that is chosen and sets up the display as a time-lapse animation. You can also use this technique to go to a specific location on the map (by panning the map), specify a set of dates, and view the imagery for those dates as an animation.
Expansion Questions
► Under Events, select one of the options for Wildfires and examine the animation of imagery by stepping through the imagery instead of letting it play. How are the capabilities of the MODIS sensor demonstrated here as being extremely useful for monitoring phenomena such as large- scale wildfires?
► Under Events, select one of the options for Volcanoes and examine the imagery of that date and the next couple dates by stepping through the imagery instead of letting it play. How is the large-scale volcanic eruption seen by the MODIS sensor?
5.The Historical Topographic Map Explorer is a great USGS online tool for examining historic topographic maps over time. To get started, go to http://historicalmaps.arcgis.com/usgs. When the Website opens, you need to type in a location. Start with Orlando, FL. When the basemap of Orlando appears, click on it to open the historical timeline of topographic maps at the bottom of the screen. In the timeline, the dates of available topographic maps (and their map scales) are shown. If you click on one of the dates, the corresponding topographic map is added to the view in its georeferenced position. If you click on a second date, that map is added as well.
In the table of contents on the left side of the screen, maps can be reordered (in which case the map at the bottom of the stack is drawn first, and maps at the top of the stack are drawn over it), removed (by clicking the X for the map), or made semi-transparent (with the slider bar under each map). To see how this works, add the 1:24,000 scale topographic map for 1956 and then add the map for 1970. Use the slider bar to make the 1970 map semi-transparent so you can see the changes from one time period to the other. Next, add the 1980 map and compare it to the 1970 map; then add and compare the 1995 map to the 1980 map.
Expansion Questions
► How did Orlando change, and where did it expand as a city from 1956 to 1970? From 1970 to 1980? From 1980 to 1995? From 1956 to 1995?
► Look for your own local area and see what historical topographic maps are online for your location. What map dates are available to view? How has your area changed significantly on the maps from the earliest time period available to the latest available time period?
6.The USGS distributes 3DEP data through The National Map. To see what types of elevation data are available, go to the TNM Download viewer platform at http://viewer.nationalmap.gov/basic. Under the options for Data on the left side, put a checkmark in the box next to Elevation Products (3DEP). This will allow to you see all of the available elevation resolutions for DEMs from the 3DEP program. Under this, click on the option Show All Availability, and the option Availability Legend appears, showing a color scheme of the resolutions of DEMs that are available for different areas. For instance, you can see which areas of the country have available 1-meter DEM elevation data. By searching for an area in the search box above the map, you can see what kind of DEM data is available for that location.
Expansion Questions
► What resolutions of 3DEP elevation data are available for Topeka, Kansas?
► For your own local area, what types of elevation data and what resolutions of data are
available?
7.Cesium is a free JavaScript API that can be used for designing 3D Web applications. (See page 540 in Chapter 15 for more about using JavaScript for Web-based programming.) The open source Cesium can be used for rendering geospatial data on a 3D virtual globe and accessing it through a Web browser. To see some examples of using Cesium for 3D on the Web, go to https://cesiumjs.org/demos.html. Check out some of the links to many Websites that use Cesium for 3D visualization, including the Swiss Federal Geoportal, FodarEarth, and Shake Finder (for viewing earthquake data).
Expansion Questions
► How are many of these demos using 3D visualization with Cesium to showcase their applications?
► How does the addition of visualizing these kinds of geospatial data on a 3D virtual globe in your browser aid in interpreting the data or communicating the concept to the viewer?
8.Figures 14.10 and 14.11 are both images of 3D structures in Google Earth, but they’re far from being the only places that have been designed in 3D for the software. For this application, open your Web browser and go to https://earth.google.com and launch Google Earth. In the search box, look for Boston, Massachusetts, and look around Boston Common and the downtown area. If you click on the button marked 3D, Google Earth changes into a perspective view, and the buildings and skyline of Boston appear in 3D. You can double-click on the small white and red arrow control to exchange places with the large globe control, which enables you to navigate around the 3D scene of Boston. You can also hold down the Ctrl key on the keyboard and move the mouse to tilt the perspective on the view. Use these controls to fly around the city and see how Boston has been put together in 3D.
When you’re done, try looking at the design of 3D buildings in other cities, such as San Francisco, London, and Paris. Check out how 3D visualization of objects in Google Earth extends beyond just buildings to features such as the Golden Gate Bridge, the London Eye, and the Eiffel Tower.
Expansion Questions
► Check out your own local city in Google Earth. Has the city been created in 3D for Google Earth? What prominent local features (beyond buildings) can be viewed in 3D?
► Use Google Earth to fly through and examine the Las Vegas Strip in 3D. What areas and features of the Strip really pop when viewed in 3D with Google Earth?
9.To examine some of the applications of Esri’s Living Atlas of the World, point your Web browser to https://livingatlas.arcgis.com. Click on Apps at the top of the Web page to see examples of multiple Web apps created through the use of the data available in the Living Atlas. You have already seen some of these apps—such as World Imagery Wayback, USGS Historical Topographic Map Explorer, and Landsat Explorer—in Hands-On Application features elsewhere in this book. You can also examine some apps that may be new to you—such as Esri Drought Tracker, Water Balance, and U.S. Precipitation Forecast—to see how the Living Atlas of the World data has been utilized in creating useful and intuitive Web applications.
Expansion Questions
► What sort of real-world applications have been developed using the Living Atlas data, and what have they been used for?
► How are the USA Wildfires, Arctic DEM Explorer, and Intact Habitat Near Me apps being used to visualize and communicate geospatial information?
10.To examine a bunch of different Story Maps, point your Web browser at http://storymaps.arcgis.com. This Website is the place to begin with Story Maps. If you already know what kind of Story Map you want to create, you can click the Apps option and then select the type of Story Map you want to make. To view the different types of Story Maps available, from the home page, you click Gallery. The Story Maps Gallery shows a wide variety of Story Maps created by Esri as well as people from the larger geospatial community. On the left side of the screen, under Story Map App, you can click to view different kinds of Story Maps that use the various map types— including Map Tour, Map Journal, Shortlist, Swipe, and Spyglass. Story Maps are also grouped together by theme; by choosing one of the options under Subject, you can find Story Maps in categories such as In the News, Nature and Conservation, and Sports and Entertainment. Investigate some of the different types of Story Maps as well as a sampling from various subjects.
Expansion Questions
► Choose three subjects related to your own interests. What topics (or stories) are being presented with Story Maps in these categories?
► Look at Story Map examples from the different types available under the Story Map App heading. How does each one present the topic (or story) uniquely?