Grado de dificultad: 3 por el idioma, 2 por el tema técnico
Google Earth is free
If you do not know Google Earth, you are missing something great. However, you may be already using it without knowing what it it.
If you visit “Google Map” page (https://www.google.com/maps), searching some location or a route to get to a date, down on the left of the screen, you will find a small square with the word “satellite” and a tiny photo of what looks like a map.
It is actually a photo of the same area shown on the main screen. Then, clicking on this square, the display switches to photographic mode, showing a satellite photogram of the area, instead of a simple map.
To be fair, Google had some issues with “Earth” in the past. It became almost unusable for a while. These times are pasted, and Google Earth is stable again, and here to stay, apparently (#CrossedFingers). It is available for Windows, Linux and Mac.
What is its purpose?
Of course, you will need a rather powerful video card on your computer, because the precision of the maps is generally very good and demanding for your display.
You will also need a good Internet connection (hopefully above 20 Mbit/s), if you want to get a smooth experience and a quick display of high-level details.
If some of the above is missing, you will have to be patient.
This is the first use one would think of: to locate your home and recognize the streets in which you use to drive. This further helps a lot when it comes to discover places you never visited before.
It wouldn’t be fair from us to forget the great Open Street Map, on the mapping theme (completely independent from Google – and completely independent alone).
This App within the App is among the most “job creators” in Google Earth. People actually drive everywhere with cars equipped with a weird dome on their roof, with which they take panoramic photos in every directions (360° horizontal and vertical).
The app works as follows: Upright on the screen, there is a set of controls, to navigate through the map, in addition to the “left click” classical method, on the map/photo to move it, and “scroll wheel” to bring it nearer.
The third button is an orange dummy character. Like the message on screen says “drag to pass to Street View”, the way it works is:
- Locate the place you want to see from the ground (as if you were in that place
- Left click and drag the dummy over that place then release it.
It is a very handy tool to get a realistic view of an area. Therefore, it is widely used by professionals of many disciplines, when preparing a project.
This feature is the main purpose of Google Earth: it provides 3D maps, what cartography specialists call DEM (for “Digital Elevation Model). Following snapshot gives an example of how a 3D view of a city can look like.
Google Earth is, for that feature, part of the toolbox of many professionals, when it comes to display any part of the planet, to get terrain elevation information. However, it is not the best one to generate such information.
The accuracy of the DEM database is also inferior to that of private vendors who provide down to submetric definitions.
However, due to Google Earth wide availability and easiness of use, many cartographers use its graphic interface to publish databases for professional use.
Let’s dive a little more in this cartographic world.
DEMs are not enough information when it comes to infrastructure analysis.
The image below shows how detailed such a 3D design can be (they even rendered the trees).
There is a dedicated tool, called SketchUp provided by Trimble. It is a fun tool for artistic design. There are other more global technical tools, based on the same method used to generated DEMs. That is through stereoscopic imaging from satellites and aircraft (planes, helicopters, drones) photography, radar and LIDAR.
With this powerful set of tools, one can actually reproduce an entire city with sub metric details.
As you can imagine, the range of applications is wide.
Some examples we know personally, belonging to a nerdy population of specialists:
- Simulation of radio propagation for cellular network in dense urban areas.
- Optic fiber backbone routing in rural zones.
- Cable catenary computation for energy transport infrastructure (and optic fiber).
- Rural fields distance and area assessment.
The list goes on and on (we guess they will do it on the moon too, if not already started.
Sub oceanic database
All that was described above could be very new for a vast majority that doesn’t know how useful Internet is to share technical information. However, the real purpose of this post was less about Google Earth and more about something rather new in it.
Down center of the screen, you can read the following information message about the databases it uses.
The others acronyms are better known by ocean explorers:
- NOAA (National Oceanic and Atmospheric Administration) is known for its action during the hurricanes seasons, and focusing on all oceanic matters (fishing, climate, currents).
- NGA (National Geospatial Intelligence Agency) former known as National Imagery and Mapping Agency (NIMA) until 2003. This agency is very useful during natural and man-originated disasters (more on land that water, but still).
- GEBCO (General Bathymetric Chart of the Oceans) is the most interesting for the end of this post.
If you use Google Earth to look at the information it provides on under-the-sea elevation, you will immediately note that there is a very detailed map (knowing how complicated it is to map under the seas).
This is the underwater equivalent of DEM, and managed exactly the same way.
A closer look will raise questions about the strange scars that can be seen (example just below).
These are not exactly scars. As you can see, these are straight lines “like drawn” under the water.
What are these lines exactly? Well, mapping under the water is very complicated and demanding: the radars and Sonars have a limited angular range. They allow exploring down to very deep distances, but with a very narrow angle.
The scars you can see, if you get closer, are high definition corridors in which mission boats analyzed the bottom o the sea for different reasons (submarine routes, intercontinental subaquatic optic fiber laying projects). See a sample on the following image.
This information is very valuable for future activities in the same area, and is constantly improving with each new collected data.
A recent project, connecting San Andres colombian island to Tolu (Colombia north cost), was almost entirely designed thanks to previous underwater high detail cartography (a great thank you to Jorge García for his invaluable insight on the general subject).
Typical project that take advantage of the undersea cartography are:
- Intercontinental optic fiber laying (and maintenance), obviously,
- Offshore Eolic parks,
- Submarine electric turbines.
We will look for additional insights from Jorge on the topic of Optic Fibers.