Argument with friend: he says Google Earth is more 3d than a globe

:smack:

The surface of the Earth is not two dimensional. It is three dimensional, although granted, the Lat/Long system doesn’t give you an altitude (actually, I just realized… Latitude, Longitude, Altitude). So yes, it IS a three dimensional system even by your definition. We just never specify the altitude unless it’s important (does Google Maps even let you specify “Dallas, Texas, 300 feet ASL”?

The surface of the Earth, or of any other sphere, is two dimensional, and to argue otherwise is to betray ignorance of what dimensionality means. A system of latitude, longitude, and altitude is three dimensional, but that just means that the lat/long system can be extended, not that lat/long is itself 3D.

I’d be very surprised if “greater resolution” was the reason the friend is thinking Google Earth is “more 3D”. That is making assumptions about their thought process which don’t make any sense at all, given that we already have some data about it: “He says that in google earth you can zoom in and look at things from different angles so it’s more 3d than a globe”. It is the different angles that are key. In addition, most globes that I have seen are not of an expensive enough construction to merit actual contours, so that may be the type of globe the friend is referring to.

Technically speaking, I suppose a globe is a three dimensional object in the real world versus a two dimensional representation on a flat computer screen. But in another sense the Google Earth representation is more “3D”: a globe typically represents the surface of the Earth as completely flat (at least, in relation to the surface of the sphere it is printed on), whereas Google Earth will not only let you see correct terrain height, but also 3D representations of buildings in its projection. People comfortably distinguish between 2D platform video games and 3D first person perspective video games, so it doesn’t seem outrageous to me to claim that the Google Earth projection is more 3D than a standard globe: it does have a lot more useful “3D” information.

In the end, this argument strikes me as a dull semantics argument, rather than one of any substance. If you are talking about the fact that the globe is a real world object and not a representation on a flat screen, it is more “3D”. If you are talking about the ability to see a representation of landscapes or major cities as they would actually look if you flew through them, Google Earth is more “3D”. Both seem like reasonable things to say, and personally I wouldn’t feel the need to get too excited about the chance to call someone an idiot.

Unless you have some version of Google Earth different from mine, it doesn’t do this at all.

The 3d buildings layer is an optional add-in (or a feature not turned on by default)

Google’s help page about this feature, which is also available in Google Maps (both desktop web version and the Android version) as outlines without the textures mapped on.

The globe did in fact have contours, i.e. the Himalayas were physically higher than the surrounding land. When my friend noticed this he conceded that there was some three-dimensionality to the globe.

Talking with him more I’ve realized that his point is probably in line with what some of you have been saying, that the map on the surface of (most) globes is a two dimensional surface on a three dimensional object. He didn’t express himself as clearly as the people who posted that here, so it’s a little unclear to me if that’s actually what he’s thinking, but I’m pretty sure that’s what he was thinking.

I initially thought he was completely off-base, but now I think I get what his point is. Still, it seems as though Google Earth is a virtual three-dimensional object, whereas a globe is a three dimensional object in the real world, whatever else you can say about the surface.

This is both a stupid question and a profound one. Nobody is saying that a globe is not 3-D because it really is round and a 3-D object. However, the coordinates to navigate around a globe are only 2-D given in latitude and longitude. Unless you have a really, really big and sophisticated globe, all you can locate is a 2-D point on the surface of it.

Google Earth is different. It is represented on a flat computer screen but there are still 3-D views for much of it. You can define what you are looking at by latitude, longitude, and altitude. That is really all that matters. The human brain doesn’t have much of a problem using a 2-D image as 3-D data and that is what is important. Like I said earlier, a Google Earth image can be 4-D as well with time being the 4th dimension. A single globe can’t do that either.

From an information perspective, Google Earth has more dimensions than a globe.

Actually, on thinking about it more, really all Google Earth is is a virtual globe. You can’t say that it’s more or less 3D than a globe, since it is a globe. It’s just an incredibly detailed one.

I have that turned on. All it does is simulate a streetview by pixalating the image. It’s not what I would call “3D”. I see from the help page it says “many areas”. That must be code for a few areas they decided to add. Still not 3D as far as I am concerned.

So, a thought occured to me (dunno if I posted it in here or just on my Facebook): With a globe of the Earth, aren’t you ALWAYS working in three dimensions simply because altitude is implied? I mean, sure, the altitude is always within a few thousand feet of sea level on a globe of the Earth, but it IS there, since the globe, even if printed 2D, is a representation of something that has three dimensions in real life. We just never think to consider the altitude because we don’t instinctively consider altitude on Earth (unless we’re in mid-air, at which point Longitude and Latitude can become really unimportant to us)

No.

That’s like saying the XY plane is 3D because the Z dimension is implied. Hey, it’s constant and therefore everything is specified by two dimensions, but it’s really 3D. Mostly because you’re not ready to admit you were wrong, from the looks of it.

Except that on a globe of the Earth, there obviously IS a third dimension, due to various places on Earth being at different altiudes. Granted, most globes that I’ve seen (and I don’t think I’ve actually seen one in a few months. Didn’t they used to be everywhere?) don’t do the topography thing.

I’ve been getting posts from various friends on Facebook explaining that this is because they use a different type of geometry when dealing with spheres, which just strikes me as a kind of arbitrary thing to do, but eh, if it makes the math easier I guess they’ll do it whatever way works best for them.

You must be thinking of something different. In no ways could this functionality be mistaken for “simulating a streetview by pixalating the image”. In certain metropolitan areas Google has compiled actual three dimensional model data for many of the buildings, and uses this and bitmap textures of the sides and roof of the building to render an actual three dimensional scene of the area. You need to check “Photorealistic” under “3D Buildings”. There seem to be quite a few places covered, for example Manhattan in NYC and downtown Cape Town, South Africa.

As an aside, I’m interested in how they got the model data. Unlike road map data there can’t be government or private records of all of this. Maybe that is true in some places but I’m reasonably confident no Cape Town city agency exists that has 3D models of all the buildings covered: sometimes it is entire residential areas with lots of suburb style houses. If I was to speculate I’d say that based on a combination of street view and satellite imagery and fancy algorithms Google was able to deduce the three dimensional models associated with a building - this sounds feasible to me if they had many different images of a particular building, etc, and saved off the corresponding 3D model data and bitmap textures. Does anyone have any information about that?

All of that, plus user-contributed content. Google Earth - Wikipedia

Best post/user name combination.

So? Height isn’t part of the model in use. You can specify where you are on the globe using two numbers that are independent of each other. This is the definition of two-dimensional.

This is a red herring: Having spherical geometry as a distinct field isn’t arbitrary (try drawing a triangle with three right angles on a flat plane!), but neither is it immediately relevant to how many dimensions the surface of a sphere has. You can answer that question without resorting to the full panoply of spherical geometry.

And that’s what I mean when they say “many” they really mean “a few” areas. Even as many as 2 or 3 dozen areas doesn’t make it a 3D depiction of the Earth.

Relating it back to the OP though, that’s more than a globe has.

google earth has better/more accurate topgraphical features you can turn on in one of the layers