Even more interesting are interactive maps, which, to some extent, have the ability to visualize the fragment in question. Such a map is a kind of virtual globe (or a fragment of the globe), so you can look at any place on the Earth and see mountains and rivers, cities and fields, forests and lakes, and not as symbols, but real photos. Such maps may become a unique educational tool, as learning geography by using them is much more interesting and effective than by boring textbooks, which may be supplemented with maps, photos, etc. They are useful for scientists engaged in various studies, as well as in any other study of terrain, for example, in planning the construction of facilities, etc. Such maps are of interest for the general public, because on them, as well as on conventional map portals, it is also easy to find on the map any point of interest, and often to create the route of the anticipated trip. The most famous and recognized among the online projects of this type are Google Maps, Google Earth and NASA WorldWind, which contain information on the entire surface of the Earth. Interactive online maps provided by them are also based on GIS, because they work with spatial data and allow finding any point on the terrain. However, unlike conventional interactive GIS maps, they display not only the usual cartographic information, but also space images taken from the remote sensing database and perfectly “stitched” together into panoramas and topographic maps, and in the case of Google Earth and NASA WorldWind – even with detailed three-dimensional visualization. Google’s services contain detailed topographic maps of only major population centers in the United States, Great Britain and partly Canada, while other territories, including Russia, are covered at a much smaller scale. For cities presented with detail, it is additionally possible to view so-called hybrid maps, which represent a high-resolution satellite image with superimposed topography. The detailing capabilities of NASA WorldWind are limited to US cities. In general the level of detail in Google services is higher than in NASA WorldWind, and there are more cities on Google Maps. The main difference between Google Earth and NASA WorldWind from Google Maps is the presence of three-dimensionality, which makes three-dimensional the entire surface of the Earth, as well as individual objects, such as buildings. However, in practice, three-dimensional reproduction is possible only for some cities. Theoretically, to travel around the Earth using Google Earth and NASA WorldWind services is enough to download free navigation software. However, in practice, normal operation requires high-speed Internet access and significant system resources.
Google Maps
Google Maps service provides the ability to view maps directly in browsers IE (version 6.0 and above), Firefox (2.0 and above) and Safari (3.1 and above). Any point in the world is displayed on Google Maps with an accuracy of up to 1:25,000 based on data from the Landsat-7 satellite. Large cities and many territories are displayed up to 1:2,000 scale, thanks to the connection of DigitalGlobe images from Quickbird-2 satellite (Google services). You can select, which area, at what scale and in what mode to view. There are three viewing modes: Map, Satellite, and Landscape. In Map mode a topographical map of the area with roads, streets and houses displayed, in Sputnik mode – stitched images of the area from satellite (with the possibility to pan and zoom), and in Landscape mode – a terrain with drawn names of settlements and roads. Depending on the location of the user, Google Maps service allows you to search for a variety of objects and get some information about them.
Of course, the search by address is implemented. If possible, it is better to enter addresses in the provided formats (“street, house, city, region” or “street, house, city, zip code”), but often the search works correctly and with a smaller set of input data.
You can search for regions and continents, settlements (cities, towns), roads, streets and various geographical objects (parks, mountains, lakes, etc.). It is even possible to specify specific coordinates on the ground (say, +38° 34′ 24.00″, -109° 32′ 57.00″).
In many places it is allowed to lay the route of movement from one point to another. This is done not quite like the above map services. You need to enter in the search box an expression like “from… to…”, press the “Search on the map” button, and then click on the “Pave a route” button. Unfortunately, this way you will not be able to lay the route from one of the Russian cities, but within Europe – as much as you want. The route will be displayed on the map as a blue line, complete with a list of numbered sections with approximate travel time. If you click on the number of any section, an information window with a detailed map will appear – you can minimize or expand this view by clicking on the “-” or “+” sign. If you want your route to avoid major highways, you should turn on the “Avoid highways” checkbox. In some places along the route it is possible to see photos of the places you are going to drive through. You can print the route.
In principle, you can create a route in another way. First you need to find the end point of the route, then left-click on the marker placed in this point, and in the information window that opens click on the link “Here”, and then specify the starting point in the field “From”. Unfortunately, for Russian cities and this option does not work.
The Google Maps service also offers a number of functions for editing and creating maps. In particular, using the function “My Maps” you can create personal maps with comments – labels, lines and shapes, as well as text messages and photos. Such maps can visually show your friends how to get to a party or event, indicate the route of a proposed hiking or biking trip, etc.
Google Earth
Google Earth service allows you to travel on an interactive map of the planet, created from perfectly “stitched” together satellite images with detailed three-dimensional visualization. On the interactive world map, you can explore any area and find any point (including by search), closely inspect the surrounding terrain, and if necessary, even lay out the best route. If you want, you can fly over the area at a given height and speed, measure distances, work with GPS, and create your own map by overlaying your objects on the original Google Earth map. You can even fly into space or dive to the bottom of the ocean. The service works with the data with the help of the program Google Earth. The program is absolutely free and has a Russian localization. The recommended configuration of your computer to work with Google Earth: Intel Pentium P4 2.4 GHz or AMD 2400XP+ processor, 512 MB RAM, 2 GB of free disk space, video card with 3D image support and 32 MB of video memory, screen resolution – 1280×1024, high-speed internet connection. The program is presented in two editions: the basic Google Earth and the extended Google Earth Pro. A detailed comparison of the editions is available here. The Google Earth edition allows you only to fly around the Earth’s surface and view its individual fragments with varying degrees of detail. Almost all of the most interesting features (measuring, working with GPS, etc.) are supported only by the commercial version of Google Earth Pro. The basic edition of the program is free; the demo edition of Google Earth Pro is operable for seven days and is fully functional. The commercial version of Google Earth Pro costs $400. The Google Earth service provides access to a wide variety of mapping information. For example, it is not difficult to find any point on our planet – you just need to go to the tab “Flight”, enter the address in the input field (it can be in geographic coordinates) and click on “Search”. You can tweak the search results by including layers in the set of interest. By “layers” here we mean boundaries, streets, roads, 3D buildings, topography, infrastructure objects, etc. Note that some layers are not displayed unless the area is zoomed in properly.
You can view 3D models of buildings, stadiums, bridges, castles, and more. To do this, just make sure that the “3D Buildings” layer is enabled, and click on the model of interest to get more information about it. For a more realistic view, it makes sense to connect the display of sun and shadows by activating the “Show sunlight on terrain” button on the toolbar. Moreover, by moving the time slider to the left or right, you can see the sunrise or sunset anywhere on the planet.
You can search for places and companies by address, company name, coordinates or keywords by activating the Company Search tab and entering the input data. To view content created by users, you need to check “Community Maps” in the “Tags” panel – the content will be displayed as blue markers.
In any found place you can set a marker (command “Save to my markers” from the context menu), which will allow you to quickly navigate to the specified location in the future by double-clicking on the appropriate item in the “Labels” panel. It is also easy to create the route of the proposed trip. You need to go to the tab “Routes”, enter in the fields “From” and “To” coordinates of the starting and ending points in the specified form (you can set the city and country) and click on the search button.
It is possible to dive into the ocean, explore elements of the underwater landscape, and look for, for example, wrecks of ancient ships. To see the ocean surface, choose View > Water Surface, and check the Ocean checkbox in the Layers panel to view underwater landmarks. You can also explore the Moon, such as taking a video tour of spacecraft landing sites and exploring panoramic photos and rare Apollo mission footage. To start exploring the lunar surface, select View > Explore > Moon. In the same way, you can travel to Mars or just outer space.
You can even travel back in time and see how different places on the map have changed over time. To do this, you just need to click the “Show Historical Images” button on the toolbar, and then move the slider in the upper left corner of the 3D View window. Any of the maps you view can be printed out, and you can also send the image or a tag to it by email. In addition, maps can be annotated using the drawing and outline tools, and saved (like the original maps) in KML files used to distribute geographic information.
NASA WorldWind
The basis for travel on the NASA WorldWind service is an interactive map of the planet, created from perfectly “stitched” together satellite images with detailed three-dimensional visualization. Large cities and many territories are displayed on it up to a scale of 1:2000 due to Shuttle Radar Topography Mission (SRTM) images. On the interactive map, you can explore any area, find any point, including by search, and closely inspect the surrounding terrain by shifting and zooming in on the desired fragment. This service also has a daily updated database of natural disasters: typhoons, floods, forest fires, volcanic eruptions, dust storms, etc. It is possible to trace the dynamics of changes in the areas of the Earth where such natural disasters occurred. The service works with data using the NASA WorldWind navigator program with the same name, which you need to download and install beforehand. The program does not have Russian localization and works under Windows 2000/XP. The recommended configuration: processor Intel Pentium 3,1 GHz or AMD Athlon and higher, RAM 256 Mb, free disk space 2 GB, 3D-video graphic card and high speed internet connection. This utility-navigator can be used completely free of charge. When you run the program for the first time, the settings wizard is activated, which allows you to set the maximum memory size for caching files and to correct the Internet access parameters. Later on, you can change the parameter settings through the menu “Tools” > “Configuration Wizard”. NASA WorldWind Navigator program provides access to the most diverse cartographic information. In order to find the point of interest on the map, just activate the tool “PlaceFinder” in the opened window specify, for example, a city, click on the button “Search”, then select the desired one in the search results and click on the button “Go”.
The map can be viewed in the scale you want (zoom in/out is made by double left/right mouse clicks correspondingly), and the set of objects displayed in it can be corrected by turning on or off certain checkboxes in the layer manager (the button “Layer Manager”).
However, the images with detailed three-dimensional visualization can be seen only for large cities on the territory of the USA, where the images are taken from the database of the United States Geological Survey (USGS) and have higher resolution (0.25 m/pixel). On the rest of the territory, you will see only blurred images under high magnification, because it is represented by lower resolution images from the Landsat satellite. For a list of locations throughout the United States where you can view 3D imagery, go to this address. To view images in this mode, you must activate the USGS Urban button, or turn on the Layer Manager > Images > USGS Urban Area Ortho checkbox. The display mode can be switched back by clicking on the “NLT Landsat” button.
NASA WorldWind service can also be used to study the dynamics of cloud cover changes, hurricane development, seasonal changes, etc. For example, you can almost in real time (data are updated every three hours) see the layer of clouds over a particular land surface by clicking on the “GlobalClouds” button. To see the cloud cover on different days, you need to right-click on the GlobalClouds layer in the Layer Manager and select the “Properties” command from the context menu, where you can change the settings with the “Next” and “Previous” buttons.