Like the title says. I’m trying to explain triangulation to my actual five year old, but don’t really understand it myself. Help!
In: Earth Science
Let’s say you want to know how far away a tree is without actually walking to it. So you put two stakes in the ground at a known distance.
You go to one stake, and draw an imaginary line between you and the tree. The line between the two stakes and your imaginary line forms an angle.
You to the other stake, and draw a new imaginary line between you and the tree. You now have a second angle.
With the known distance between the two stakes and the two angles, you can make a single, unique triangle with the two stakes being two of the corners of the triangle. The third corner will be where the tree is.
You can use math to calculate the distance from the tree to either of the two stakes.
Think of it like the game Marco Polo. You say Marco with your eyes closed but have to listen for the direction of when your friends respond “polo!” With enough listening you can find your friend.
With cellphones the towers listen for cellular transmissions from a single device and with enough data can pinpoint the source (strong signal received at one tower, weaker signal at the other tower, weakest signal at the third tower = known location near first tower).
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Imagine that you are a spot on a map. You can hear a signal, but can’t determine where it’s coming from. But you can figure out how far away it is by how strong the signal is. So, you draw a circle around your position at that distance. You just don’t know in what direction the signal is coming from.
So now you ask someone else in a different location if they can hear the signal. They can also hear the signal, but also cannot tell which direction. Just strength/distance. So draw a circle around their point on the map as well. Now, look at the 2 circles around your position and their position to try and find where the circles overlap to find the location of the source. The problem is that the distances are going to overlap in TWO locations. So, the source could be in either of the two locations. How do we find out which one?
Find a third person. Ask them. Draw another circle. The source will be where the 3 circles overlap. You’ve now triangulated the source.
Here’s a really simple way to do it.
Get a piece of paper and draw one circle. In the center is a cell phone tower. That cell phone tower picked up your signal (that’s the circle). The problem is that it doesn’t know what direction you are.
Now draw another circle that somewhat overlaps your previous circle. The second circle is another cell phone tower that picked up your signal.
You will have two points that cross. Between the two towers they can say that you’re in one of two places.
Finally, draw yet another circle that goes through one of those two points. The center of the third circle is ANOTHER cell tower that detects your phone signal.
The intersection is where you are. It is called “triangulation” because it needs 3 sources to confirm an accurate location.
Edit: what I described is TECHNICALLY trilateration. HT: /u/n21brown
Triangulation is a method for determining a position that is dependent upon the distance between the two measuring devices and the angle between the two points and the object. Effectively you then use maths to solves the triangle.
It’s a technique used in chess endgames to waste a move and put the opponent in zugzwang, i.e. a situation where they would like to pass their move (but the rules don’t allow them to).
You, your husband/wife/gf/bf, your 5yo and your very intelligent dog are in a big, dark room with a tiled floor. You want to know which tile is your dog standing on so you tell him to bark. Each of you turn around and face the direction the sound came from. You tell the dog to move out. Each of you is holding a very long, straight stick and lays it on the floor, pointing in the direction of the sound. You tell the dog to turn on the lights, the point where all 3 sticks meet is where the dog was.
There are a bunch of wonderful answers on here already, but just to add, your brain does this automatically whenever you see or hear something.
Your eyes are two points, and if you know how big an object is, you get enough points and angles to estimate how far away it is.
Your ears hear sounds individually, so whenever a noise sounds, even with your eyes closed, you can still point out a direction the noise is coming from, and (if you can identify what the noise is) how far away it is.
(Also, because we only have two ears, it can be hard to determine if a sound is coming from either directly in front of you, or directly behind you, because the sound is equidistant from both ears.)
Both instances are your brain using triangulation to give you enough information to interact with the world, which blows my mind whenever I think about it.
If you draw one circle, there are an infinite number of points on them.
But if you draw two circles with different centers, there are only two points that are on both, like a Venn diagram.
And if you draw three circles with different centers, there will only one point that’s on all three.
(All of this is very handwavy to demonstrate the principle. Sometimes there will be zero, sometimes there will be infinite. That won’t happen if you’re triangulating something properly)
This is the idea behind triangulation. If you use a laser or radar or an echolocator, you can get a distance from you to something. Or in the case of a gps satellite, it tells you what time it was when it sent the signal you receive. Either way, the data you get from one signal is how far away the thing is from you, and you can represent that as a circle with a radius of that distance. You don’t know where it is but you know it’s somewhere on that circle. If you get a different signal from a different point, you now have a different circle, with a different center and a different radius. You know that the source of the signal must be on *both* circles because you measured it that way, and like we said earlier, that means there’s only two places where it could be! Taking one more measurement in the right place you can determine which of the two points it is.
Triangulation is the process of using angles and distances to find a point on a map.
This is most commonly used in navigation where you don’t have any obvious features to follow like a road or river.
Imagine you are standing out on a moor, and you can see a mountain in the distance. If you have a compass you can use that to work out the bearing (direction) from where you are standing to that feature.
If you then take a map, and draw a line from the feature you are looking at, backwards along that bearing, you know that you are standing somewhere along that line.
If you then pick another feature in the distance and repeat the process – take a bearing, then draw that line on your map – the point you are standing at is where those two lines intersect.
You can also use this maths the other way round to do things like find the position and distance of a distant point if you have two known points to measure from – this is how the British Ordnance Survey mapped the entire country – they set out two fixed points (marked with concrete pillars known as triangulation points) that they knew the distance between, and by measuring the angle from each point to a distant third point (such as the top of a mountain) they could place that third point on a map that they were drawing.
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