Map projections vs a Globe Map

[Gormadoc]

I was wondering why we still use Map projections in these Global scale HOI games.
I assume it has something to do with added programming complexity versus benefit from using a precise map.

But what are the actual issues that needs to be resolved before using a Globe map instead of a map projection.
Anyone with enough experience in this, that could educate me a bit?

 

[BeauNiddle]

The original xcom used a globe for a map so it's not that difficult to do.

The problem is 90% of everything you want to look at is angled away from you. On a normal map everything is directly facing you, on a globe only a minor circle in the middle could be considered facing you, everything else has depth perception issues (if not completely occluded). It makes scrolling around to check things at a glance much harder.

Planetary Annihilation was on globes. It didn't really catch on.

 

[Synicus]

What does one do with the corners of the screen? Perhaps we need round monitors?
Biggest issue a gfx engine that can better handle all the 3d units and weather and look great.
There are better ways to move most distortion to the pacific on a flat map but not with a seamless edge that is needed for smooth sailing,
Also if your talking about changing the game gfx so drastic, your looking at HoI V!

 

[bitmode]

I assume it has something to do with added programming complexity versus benefit from using a precise map.

Yes, the simple answer is the dated Clausewitz engine that the game is based on is geared for 2D coordinates.

The problem is 90% of everything you want to look at is angled away from you.

The intent is not clear from the OP, but the game could also simulate a globe for the benefit of accurate distance and area calculations while still retaining a visual 2D map.

 

[Louella]

Imperator: Rome uses a curved map i think ?

 

[safe-keeper]

What are the advantages of a globe, though? Both from an immersion point of view and in terms of practicality, I prefer being able to see as much as possible at the same time.

edit: what I'm talking about in terms of immersion is how World War II generals didn't look at a globe, they looked at paper maps of the theatres of operations.

 

[Simon_9732495]

To display the globe on a flat monitor screen you need to use a projection.

There are many:

List of map projections - Wikipedia

en.wikipedia.org

The first one looks a bit like the Map in HOI4, so maybe that is used.

I think using another projection is not too hard. Which projection would you use and what would be the benefits of changing it?

Edit:
See also: https://en.wikipedia.org/wiki/Map_projection

Edit2:

Due to distortions inherent in any map of the world, the choice of projection becomes largely one of aesthetics.

From: https://en.wikipedia.org/wiki/Map_projection#Which_projection_is_best?

 

[BeauNiddle]

Yes, the simple answer is the dated Clausewitz engine that the game is based on is geared for 2D coordinates.


The intent is not clear from the OP, but the game could also simulate a globe for the benefit of accurate distance and area calculations while still retaining a visual 2D map.

Isn't the HOI4 map province based with distance based on node data? (i.e. not pixel distance)

If so then updating the distances to be globe based should be trivial shouldn't it? (if they're not already)

 

[bitmode]

Isn't the HOI4 map province based with distance based on node data? (i.e. not pixel distance)

If so then updating the distances to be globe based should be trivial shouldn't it? (if they're not already)

The provinces are a collection of pixels in the province map. Things like air plane ranges or distance between provinces are internally calculated in map pixels. There is no higher abstraction like a map projection or longitude and latitude.
The only game mechanic giving an impression of a globe is the shape of the day-night cycle. I'll see if I can find the formula again.

 

[Louella]

Range circles for aircraft would become some very weird shapes on most of the map, if the real range was used.

 

[Mr.Bajskorv]

I think the main reason is because it's easier, and that Paradox and gamers is mostly used to a 2d map. Navigating around a spherical glode isn't hard, it's as easy to get adjusted to after 5 min of play.

A 2d map in games almost always tend to make the regions around the polar unintresteting, because of everyting is represented as being much father away then it really is.
A sphereical or ellisoid map is superior in almost every way.

 

[Simon_9732495]

A sphereical or ellisoid map is superior in almost every way.

Why do you think that? I'm not sure about it...

If a globe is implemented ingame, it has to be projected somehow to the flat monitor.
If a 2d map is implemented ingame, the projection from the globe to 2D has to happen before.

You will have the problem of projection anyway.

If you design the map in a way that the representation on the monitor looks like a globe (like the XCOM globe), you'll have the problem that everything is dependent on the viewpoint.
If you scroll the world, length in pixel and area in pixel will change.
I'm not sure if that is optimal for grand strategy.

 

[bitmode]

The day-night cycle code translates the center pixel (x, y) of a province into a GMT offset and a latitude like this:

GMT offset = (x - GMT_OFFSET) / map_width

latitude = -cos(pi * (
    (NORTH_POLE_OFFSET - SOUTH_POLE_OFFSET) * y / map_height + SOUTH_POLE_OFFSET)
))

Which map projection uses a cosine for the latitude calculation?

Edit: applying the projection to a normal world map looks like this:

 

[bitmode]

What does one do with the corners of the screen? Perhaps we need round monitors?

The problem is 90% of everything you want to look at is angled away from you. On a normal map everything is directly facing you, on a globe only a minor circle in the middle could be considered facing you, everything else has depth perception issues (if not completely occluded). It makes scrolling around to check things at a glance much harder.

I think you are both overestimating the typical zoom level. Yes, if you want to see all of Eurasia and Africa (or the whole world) at once and zoom out very far on a globe, you'll get a lot of distortion and empty space: https://earth.google.com/web/@23.43746536,60.13720398,-4679.1071407a,12518770.56237102d,35y,0h,0t,0r
But when zoomed out this far in the current game view, you can hardly do anything except assigning fleet areas. You'll see neither divisions, combats, nor victory points:

This is how a more moderate zoom level would look like: https://earth.google.com/web/@48.02...5872.10029662d,35y,3.65534854h,6.20439171t,0r


At a level where divisions get shown for individual provinces, there is hardly any distortion left: https://earth.google.com/web/@55.11...574311a,927437.6724869d,35y,3.45907552h,0t,0r

 

[Praetori]

I was wondering why we still use Map projections in these Global scale HOI games.
I assume it has something to do with added programming complexity versus benefit from using a precise map.

But what are the actual issues that needs to be resolved before using a Globe map instead of a map projection.
Anyone with enough experience in this, that could educate me a bit?

The engine works with the base-maps pixels and populates a lot of things based upon it (even distances). Pixels are square and thus you'd get huge issues pretty quickly if mapped to a sphere (despite converting to a different projection).
Things like the geographies of provinces, states etc would probably be a lot harder to mod (or not harder depending on what replaces the pixel map but at least less accessible for people to get into).

That said. For future titles there's nothing preventing a globe but it IS much easier to work with flat geometries for a lot of different reasons.
Aesthetically I personally also think that the flat-map style works better in games pre-space-flight while the "globe" style of overview works better for modern or sci-fi titles.

There are benefits of doing vectorized geometries instead of how the engine currently does it but on the other hand you can do that no matter if your coordinates/projection is flat, spherical, donut-shaped or whatever (the latter will make your eyes bleed a little if projected in 2D though).

 

[AFilthyCasual]

I would prefer a globe because it would allow for more realistic travel and control zones by ships and planes, and would also make everything correctly proportional so Europe isn't twice its actual size. However I don't think the Clausewitz engine can handle it, they would need a new engine.