How Google Earth Functions

Many of us have relied on online mapping tools for years. They're indispensable for those who struggle with directions within a few miles of home, and they're also great for those who love discovering locations.

Now, imagine the impact of GoogleEarth—a tool that has captivated users and even sparked South Korea to call for alterations to the program.

Google Earth is more than just a simple mapping tool. By entering "Denver, CO" into the search box, you can find out its location relative to Grand Junction, CO, and get directions from your place to 1600 Curtis St. in downtown Denver. But that's just the beginning—this search also reveals that 1600 Curtis St. lies within the 80202 zip code and that there are 12 Starbucks nearby. Zooming out, you'll see the area shrink into a satellite view of the Earth, and you can zoom back in as if you're falling from space directly to that address. Want something even more fun? Click "Forbidden City" in the "Sightseeing" column, and you can fly from 1600 Curtis St. in Denver to the Forbidden Palace in Beijing, China, just like Superman.

And just when you thought the world couldn't get any smaller.

The application is relatively simple to use, yet it offers numerous features worth exploring. Discover how Google Earth collects its images and data, and learn how to start using it to explore various functions and customization options.

What exactly is Google Earth software?

Google Earth is available as a desktop application, though it requires an internet connection to function. Upon opening Google Earth, it automatically connects to Google's servers, granting access to vast amounts of geographical, political, and social data. For example, you can view a city with various "layers" enabled, such as topographical data, population statistics, and crime rates. The layers and map controls, like zoom, tilt, and rotate, are all found within the Google Earth interface.

The best part? The basic version of Google Earth is completely free right now. However, this may change in the future. So, let's make the most of it by downloading the free version from Earth.Google.com while it's still available. If your computer runs Windows, Linux, or Mac OS X 10.3.9 or later, and is no older than five years, you should be good to go. If your system doesn't meet the requirements, keep reading to find out what you'll be able to do once you upgrade your equipment.

Upon launching Google Earth and exploring, one of the first things you'll notice is a major "wow" factor: certain information appears in 3-D, while the non-3-D content is still a photograph—there are no drawn maps. The primary visual data is sourced from satellite images and aerial photos captured by planes.

Google Earth is packed with numerous features that would likely take months to fully explore, but its core functions are broadly grouped into the following categories:

The basic version of Google Earth is free, offering an incredible experience. However, if you're looking for more advanced features or intend to use the software for commercial purposes, subscription-based versions of Google Earth are available with additional functions. Continue reading for a deeper dive into the essentials. ­

Google Earth Maps Features

The best way to familiarize yourself with Google Earth is by choosing a location and seeing what information it provides. For instance, if you search for "675 Ponce De Leon Ave. Suite 4500, Atlanta, GA 30308" in the Google Earth search bar and hit "Search," you'll zoom in from space straight to Mytour headquarters. What you'll see is a photograph of the location.

To gather more details and turn the image into a true map, you’ll need to activate some layers. Some of the available layers include dining options, hotels, banks, roads, terrain, shopping centers, grocery stores, gas stations, parks, transit routes, schools, and geographic features.

To craft a practical, useful map, simply enable the "roads" layer. Zooming out a bit will give you a comprehensive driving map of the wider area around 3350 Peachtree Rd. in Atlanta.

Suppose your tour of Atlanta starts at Mytour headquarters, and you're planning to catch a Falcons game at the Georgia Dome. By clicking the Google Earth directions button, you'll find two fields: one for the starting location (3350 Peachtree Rd, Atlanta, GA) and the other for the destination (1 Georgia Dome Dr NW, Atlanta, 30313). After clicking "Search," you'll be shown both written directions and a highlighted route on the map, which automatically zooms out to display the entire journey from Mytour to the stadium.

Google Earth Search for Business

You can easily save, print, or email the maps and data you've created in Google Earth. There are buttons in the toolbar that allow you to perform each of these actions.

Now that the Falcons game is over and you're looking for a meal, you can use the find businesses feature to help you out.

The first step is to re-center the map on the Georgia Dome. To do this, simply left-click anywhere on the map and drag it upwards until the Dome is in the center. Alternatively, you could type "1 Georgia Dome Dr." into the search box and fly directly there, which will also center the Dome on the map. You can zoom in for a better view of the area.

To locate restaurants near the Georgia Dome, click the "Find Businesses" tab, enter "restaurants" in the "What" field, and leave the default setting of "Current view" in the "Where" field. After clicking "Begin Search," you'll see a list of options that match your search criteria.

The map zooms out slightly and re-centers to display as many restaurant results as possible while still keeping the Georgia Dome in view. However, that's not the only method for finding restaurants. You can also activate the "Dining" layer, which doesn't require any keywords but instead explores the entire Google "Dining" category for nearby restaurants. Here's what happens when you do that:

Now, you've got even more choices to consider.

In this section, we've explored most of the fundamental features of Google Earth. While many of the tools we've discussed are also available in other mapping applications, they might not offer the same visually stunning experience that Google Earth provides. What truly distinguishes this program are the features that turn it into more of a hobby than just a tool.

Google Earth 3-D and Other Features

Video Flyovers

One of the most incredible features of Google Earth is the flyover. For example, if you're viewing Atlanta, Ga., and search for "Nepal," the program doesn't just magically transport you there. Instead, it actually flies you over the terrain and countries beneath you as you journey to your destination. This flyover feature is particularly useful when getting driving directions. At the bottom of your screen, with your step-by-step directions, you'll find a "play" button. Clicking it makes Google Earth fly you over your route, turning and adjusting as needed, so you can preview exactly how the drive will unfold.

3-Dimensional Views

Google Earth has developed 3-D models for numerous major U.S. cities. While these aren't precise replicas, they're basic gray 3-D renderings that still provide a solid sense of the city. More recently, Google Earth has begun supporting textured 3-D models that look more realistic. Some of these models come pre-built, but the majority are created and imported by users through the free Google SketchUp program. As with any other view, you can use the "tilt" and "rotate" buttons in the navigator to experience the full 3-D effect.

Exploring the World Through Sightseeing

Haven't had the chance to visit the world's iconic destinations yet? Google Earth is here to help. You can zoom into famous landmarks worldwide by simply selecting a location from the "Sightseeing" section, which highlights the most renowned destinations like the Eiffel Tower in Paris, the Grand Canyon in Arizona, and Vatican City in Rome.

Alright, so video flyovers, 3-D views, and global sightseeing are already impressive, but hold on until you experience the wonders of Google Sky.

Explore Google Sky

Google Earth astonishes users with its ability to take you anywhere on the planet. In August 2007, Google expanded this capability with the launch of Google Sky, allowing users to venture beyond Earth and into the stars.

By simply clicking a button, users can enter Sky Mode, shifting their view from Earth to space. With high-resolution imagery from NASA, the Digital Survey Consortium, and the Sloan Digital Sky Survey, Google Earth presents a precise and captivating view of outer space. You can fly through the cosmos just like in Earth mode, exploring distant corners of the universe.

Similar to the Earth view, Google Sky offers multiple layers for display. You can locate constellations by name or watch them appear on the screen. The Backyard Astronomy layer provides more detailed information about some of the most notable celestial objects, using three astrological catalogs. You can highlight galaxies, nebulae, star clusters, and well-known stars to learn about their locations, histories, classifications, and even access links to NASA's information database. Additionally, the Hubble Showcase offers stunning images taken by the Hubble Space Telescope, along with detailed data about these cosmic objects.

Two exciting features of Google Sky are the Moon in Motion and Planets in Motion layers. These show the movements of the moon and planets across the sky from your location on Earth. NASA captured images every hour for three months to ensure accuracy in the paths. A slider bar lets you select the time period you want to observe. Simply click to see the moon or planets in motion. If you click on the moon, the program will provide its position for that specific date, the phase, its distance from Earth, and its brightness. Clicking on the planets reveals details like their size, distance, and magnitude.

Google Sky also offers two fascinating tours of the universe. The User's Guide to the Galaxy takes you on a journey through several well-known galaxies, while the Life of a Star tour shows the full lifecycle of a typical star, from birth to death. The fact list details the stages of each star and its place in the cosmic order. In both tours, you can choose to click through one at a time or download the entire experience for a continuous voyage through space.

Now that you've explored the exciting features of Google Earth, let's dive into where it sources all the data to make everything function seamlessly.

Google Earth Map Data

Google Earth began as a premium program called Keyhole, which was priced at approximately $90. After Google acquired Keyhole, they gained access to vast amounts of digital mapping data, and set about creating a free version of the software for everyone to download. Now you’re up to speed on the history.

Google Earth’s photographic maps are primarily sourced from satellites and aircraft. These images, along with other mapping data, are provided by companies like TeleAtlas and EarthSat, who specialize in converting photographs and maps into digital formats for commercial use. Since the data is gathered from various sources, it comes in different resolutions, which is why some areas are crystal clear even at street level, while others are blurry from afar. Google is working towards achieving high-definition coverage of as much of the world as possible. The imagery you see on Google Earth isn’t in real-time; the data is typically no older than three years and is constantly updated as new information becomes available.

Google Earth offers detailed street-level coverage for countries like the United States, Canada, and the United Kingdom, allowing you to zoom in, view street names, local businesses, and get directions. Other regions such as Western Europe, India, and Japan also have a significant amount of information, but coverage in other parts of the world can be patchy. For example, you can zoom in on the Egyptian pyramids and get a good look, but you won’t see street names or find a nearby grocery store. However, Google is continuously adding more information to its maps with each update, improving the details worldwide.

Another key source of data for Google Earth comes from the Google search engine. One of the most engaging aspects of Google Earth is its integration with Google search. As you’ve seen in the "How to Find the Fun Stuff" section, when you explore a city, you can search for nearby coffee shops, restaurants, grocery stores, bars, and more. Clicking on these listings will provide you with detailed information from Google’s search engine. Additionally, users can add a business location to the map by selecting the "Add/Edit a Business Listing" option in the Google Earth toolbar.

Now that we understand where the data comes from, let’s dive into how that data reaches your computer screen.

Google Earth Technology

When using Google Earth, many users take for granted the ability to zoom in, rotate, pan, and tilt on something as specific as their own front yard. But the magic of Google Earth lies not in simply compiling and storing these images, but in delivering them to your computer efficiently. With a 56k dial-up modem, it would take 12,400 years to download a one-meter resolution image of Earth [source: Butler]. Yet, Google Earth makes it seem like you're viewing a high-resolution image of the entire world in real-time. Overcoming the challenge of moving such massive amounts of data was one of the program's biggest obstacles.

One way to reduce transfer time is by using your computer's disk cache. You can explore the intricacies of disk caches in How Caching Works. In simple terms, a disk cache is temporary storage for files that your computer has already accessed. By temporarily storing images you've already viewed, your computer doesn’t need to re-transfer them from the source when you want to view them again. Google Earth relies on this technology to help speed up data transfer.

Another crucial element of delivering all that information to your screen involves how your computer processes and displays maps. Google owns several software patents related to the functioning of Google Earth. One particularly important patent, known as Universal Texture, is key to the whole system. Universal Texture (UT) employs two techniques for transmitting large amounts of data to your computer — mip mapping and clip stacking [source: Tanner, Migdal, Jones].

Mipmaps are a series of bitmap images that work together within a texture to create the illusion of depth. These images are arranged in an inverted pyramid structure, each level having double the resolution of the one below it. These layers combine to produce a three-dimensional representation of a two-dimensional image.

Clip stacks are segments of large mipmaps that are clipped down to a defined maximum size. The reason for clipping these enormous files is straightforward — Google Earth operates on the principle that users only need to view one segment of the mipmap at any given time. When the user specifies a location to fly to, an algorithm determines which parts of the virtual texture are required and uses only those to construct the final images [source: Tanner, Migdal, Jones].

In simple terms, Google Earth has created an enormous, high-resolution, multi-terabyte image of the entire Earth and displays it one small section at a time in manageable pieces. Zoom into your front yard, and the program will trim away everything except the yard and its immediate surroundings.

Now, let’s dive back into exploring Google Earth. In the upcoming section, we’ll discover how Google Earth can be tailored to suit your preferences.

Customizing Google Earth

What sets Google Earth apart from other mapping programs is its high level of customization. You can easily add placemarks to locations you want to revisit or overlay your own images onto a map you create. All of these tools are readily accessible through the toolbar. For those looking to get more advanced, it's possible to import your own files into Google Earth to display routes, points of interest, boundaries, and more. Similar to how a web browser reads HTML, Google Earth interprets a language called KML. By opening a KML file within Google Earth, you can display your personal data over the global map. For more information on importing data, check out the following links:

From time to time, Google Earth incorporates third-party overlays and applications, which may be sponsored by organizations like the Discovery Channel, National Geographic, the European Space Agency, and more. These layers can highlight natural wonders, significant achievements, environmental efforts, and political issues. Here are a few examples to explore.

Crisis in Darfur -- an overlay created by the United States Holocaust Memorial Museum that visually represents the genocide occurring in Darfur. When enabled, this overlay outlines the Darfur region in Sudan on the globe. Markers appear at locations where Sudanese soldiers and Janjaweed militias have destroyed villages. These markers also provide details on the number of people displaced due to the destruction of each village. The overlay also features images, videos, and articles about the ongoing crisis.

Geographic Web Layer -- a map layer that contains three sub-layers: the Best of Google Earth Community layer, the Panoramio layer, and a WikiPedia layer.

Keep reading to explore more ways to personalize your experience with Google Earth.

Google Earth Layers

Wild Sanctuary -- an overlay that allows you to immerse yourself in soundscapes collected by Bernie Kraus. He has gathered recordings from various locations around the world, ranging from tropical rainforests to the icy expanses of Antarctica. When you click on a marker, a pop-up window opens, and the sounds start playing. You can stop the sounds at any time by closing the pop-up window.

NASA -- the space agency has developed a few fascinating applications for Google Earth. One lets you explore satellite images of Mars, effectively turning Google Earth into a Martian globe. Another, the Blue Marble Next Generation application, offers a stunning image of Earth as seen from space. This image activates when you zoom out to view Earth as a globe, returning to the regular satellite view once you zoom in past the atmosphere. It also features an option to enable a real-time Global Clouds overlay, updated every few hours. Note that only the cloud layer is updated; the land images beneath the clouds may be up to three years old.

ChartGeek and EarthNC -- ChartGeek provides an overlay with Sectional Maps and TAC charts, designed for pilots. Similarly, EarthNC Plus is an application by DestinSharks.com that includes a layer with over 600 nautical charts. While these charts aren't meant to replace physical charts, they are valuable for planning flights or cruises.

Other overlays allow you to compare 'before and after' imagery of regions that have undergone significant changes. For instance, you can view satellite images of Greensburg, Kansas, before it was devastated by a series of tornadoes, and compare them with photos taken after the destruction. Users have also created animations using Google Earth to show how regions evolve over time or to visualize the impact of massive flooding caused by climate change on cities.

Google Earth is perhaps the best free download available today, and the majority of users are amazed by what it offers – though not everyone shares that enthusiasm.

Concerns About Google Earth

Google Earth provides easy access to aerial images of virtually every part of the world, which is available to anyone with a computer. However, this widespread availability has raised some concerns on various fronts.

Google Earth often leaves a strong impression on users, especially the first time they experience it. Many people are initially amazed by the vast access it offers to the world. However, shortly after that awe, they often feel uneasy as they search for their own address and think, 'This feels a bit creepy.' While many are excited by the prospect of exploring the world digitally, they aren't always comfortable with the idea of the world being able to look back at them. Could Google Earth be used by stalkers to track someone more effectively? Could burglars use it to survey a neighborhood before a crime?

When considering concerns about personal privacy, there are a couple of key points to remember. Firstly, the information available on Google Earth is not unique; it can be found elsewhere. Secondly, the imagery on the platform is up to three years old, meaning it’s not being updated in real-time. This age of the data diminishes its usefulness for those with ill intentions, like stalkers.

Another major concern surrounding the program is national security. Many countries, including Australia, the UK, and the US, have expressed concerns about the detailed satellite imagery that Google Earth provides. However, South Korea stands out as the most vocal critic, as it is technically still at war with North Korea and fears that anyone, including ordinary North Koreans, could access sensitive South Korean military sites with just a few clicks and a zoom.

If Google can access such data, it's likely that North Korea already has it too. What's more, it’s important to recognize that citizens in South Korea can easily zoom in on North Korea's nuclear research facilities, making it disturbingly simple to conduct surveillance.

The concept behind Google Earth is not revolutionary in terms of imagery—it sources its data from other providers. However, what sets it apart is its accessibility. In the past, finding a satellite image of landmarks like the Egyptian pyramids or the White House would have taken significant effort. Now, all you need to do is download the Google Earth app, and you have an instant aerial view of the world.