Curved Earth...

[Anatoli-Kagari9]

My two preferred air combat sims share a limitation: they use a flat representation of the Earth !

 

While this can be of somehow less importance to ww2 and other slow flying aircraft, modern fighter jets and their weapons are certainly impacted but the curvature, including, but not only, Coriolis effect.

 

Wonder if ED has plans for a new generation of maps tha could use some sort of geoid model ?

[Northstar98]

+1, especially if the long term goal is to make a world map (even if it's very far future and more of a dream).

 

And it's not just things like the coriolis effect, having a flat Earth model already causes problems for navigation, the LAT/LONG grid isn't actually accurate, and doesn't correspond with coordinates in DCS. On maps which are large longitudinally, it inevitably leads to some distortion.

 

There's also other things too, like realistic LOS for both visual and RADAR etc, right now I think RADARs use a workaround to approximate a curved Earth, but this doesn't apply for visual.

 

Unfortunately it would mandate a major update to every single map, and unfortunately, I'm not sure how feasible that is, if at all.

 

I did a post about it for the Marianas map (which would be the easiest to convert into a sphere) here, and the request itself has been asked for before, here's one of them.

[Worrazen]

Yeah but computers really don't like curved earth, calculations get a lot more complicated, it goes down to the core engine support and I think many other components of the sim have to be aware of this(support) to work correctly, so don't expect it soon, unless they were developing it for quite a while.

 

So it's not a bolt-on like AMD FSR could be. I don't even think other free 3D engines in the gaming world do it either yet, but I heard something is moving in that direction, but it wasn't addressed yet what will happen in UE5 in this regard, AFAIK. Something more here: https://www.reddit.com/r/gamedev/comments/k9a8g5/game_engine_with_round_earth_support_unigine/

 

Leadwerks 5 site just mentions 64-bit Worlds, if it's about the solar system I hope they also mean the curvature of the planets but ... who knows, maybe they just mean a really big flat universe plane and the planets are actually just "round" 3D models/meshes.

Edited July 23, 2021 by Worrazen

[Northstar98]

16 hours ago, Worrazen said:

Yeah but computers really don't like curved earth, calculations get a lot more complicated, it goes down to the core engine support and I think many other components of the sim have to be aware of this(support) to work correctly, so don't expect it soon, unless they were developing it for quite a while.

 

There's plenty of titles running curved Earths, it isn't a problem.

 

But yes, it isn't a simple task, though it would've been much better to do curved maps from the get go, rather than flat maps.

[Worrazen]

Perhaps it's not that big of a deal in it self, however perhaps when you count the accuracy the sim and physics would need, would get more challenging, but I'm kinda speculating there too.

 

Now whether curvature is more than just you seeing it visually, for you could simulate curvature right now by just making a huge dune across the whole map, so you'd start at 0 elevation at edges and basically climb a hill you wouldn't really notice all the way to the center of the map. Now, perhaps some of those games have fake curvature like this.

Edited July 24, 2021 by Worrazen

[Northstar98]

5 hours ago, Worrazen said:

Perhaps it's not that big of a deal in it self, however perhaps when you count the accuracy the sim and physics would need, would get more challenging, but I'm kinda speculating there too.

 

Now whether curvature is more than just you seeing it visually, for you could simulate curvature right now by just making a huge dune across the whole map, so you'd start at 0 elevation at edges and basically climb a hill you wouldn't really notice all the way to the center of the map. Now, perhaps some of those games have fake curvature like this.

 

Essentially, instead of having the maps be flat, and have flat Earth physics, we'd have maps that are essentially a segment of the surface, like this (on the right):

 

 

You'd then have to tweak the forces, such that weight acts radially inwards, instead of being uniform (parallel lines). The other forces are more to do with the Earth's rotation.

 

All of these calculations are pretty trivial to do, but over small-ish angles (like most of our maps), you could even use a look-up table if you wanted to keep it purely arithemtic.

 

And no, some games do actually model the planet they're on as a sphere, and they do really have the calculations in place to support it (some use approximations, some use scaling, some don't take into account all of the forces), but nevertheless, it is still a curved map.

 

You could have the maps be a very large featureless sphere, and just have the map be a small section of the surface.

 

In any case I think the main hurdle will be converting current maps to be shaped such that they're on a sphere, I might give a go at programming a converter, where it takes 3D coordinates using a flat map and transforms it to what that coordinate would be on a spherical map.

 

The next most difficult thing is probably implementing the maths, while it isn't particularly difficult or complicated (especially relative to flight dynamics), it will a fair amount of effort to convert everything to a spherical system.

Edited July 24, 2021 by Northstar98

[Worrazen]

1 hour ago, Northstar98 said:

And no, some games do actually model the planet they're on as a sphere, and they do really have the calculations in place to support it (some use approximations, some use scaling, some don't take into account all of the forces), but nevertheless, it is still a curved map.

 

I get it but I'm rather hesitant, particularly because I haven't digged into this topic myself ever, I risked jumping to conclusions on this forum too much back when I was initially looking into DCS performance, so I hope it's simpler as you're claiming  ... I wanted to mention this before but here's a perfect example of my dillema ... do we really need the terrain to be this landscape thing, or can all the action be on a giant mesh sphere ... why don't we have all of the other game engines have this giant gravitational sphere then if it's so easy !?!?!

 

So ... what is this, is Super Mario Galaxy curved or flat engine ?

 

 

 

 

 

[Northstar98]

1 hour ago, Worrazen said:

I get it but I'm rather hesitant, particularly because I haven't digged into this topic myself ever, I risked jumping to conclusions on this forum too much back when I was initially looking into DCS performance, so I hope it's simpler as you're claiming  ... I wanted to mention this before but here's a perfect example of my dillema ... do we really need the terrain to be this landscape thing, or can all the action be on a giant mesh sphere ... why don't we have all of the other game engines have this giant gravitational sphere then if it's so easy !?!?!

 

It's mostly reserved for things that have maps with large distances; submarine simulators, flight simulators (particularly civillian) and obviously space simulators typically all have curved maps - either using a sphere, or an approximation (such as a cylinder).

 

1 hour ago, Worrazen said:

So ... what is this, is Super Mario Galaxy curved or flat engine ?

 

 

 

No idea, but given the game, it's probably flat - it's simply not necessary to use a spherical map given the application.

 

If it does go around a sphere, then they'll be using some elements that support that.

Edited July 24, 2021 by Northstar98

[Tippis]

There's also this solution (about 23 minutes in, but the discussion leading up to it gives some relevant context):

 

The surface isn't curved, but gravity isn't fixed and instead depends on the character's location in relation to the cube.

Edited July 25, 2021 by Tippis

[Anatoli-Kagari9]

Some of the major advantages of modelling a geoid have already been mentioned in this thread.

 

I would just like to add that I do believe it is not rocket science. Microsoft Flight Simulator ( since version 5 ), X-Plane, Flight Gear, Aerowinx PSX, ELITE IFT, etc... are all using geoid representations of the Earth, with the associated benefits regarding for instance navigation, wave propagation for detailled non-satellite communications and instruments like those used these days, etc...

 

It's also important physics-wise in the flight dynamics. Check for instance how it is done in the latest encarnation of MFS:

 

https://docs.flightsimulator.com/html/index.htm#t=Additional_Information%2FFlight_Model_Physics.htm

 

under "Aircraft Attitude And Euler Angles" and "Referential Frames And Conventions"...

Edited July 25, 2021 by jcomm

[Northstar98]

7 hours ago, Tippis said:

The surface isn't curved, but gravity isn't fixed and instead depends on the character's location in relation to the cube.

 

I mean, the principle thing you need to get right, is to have the direction of weight depend on your latitude and longitude, once you've got that, curving the surface is small potatoes, essentially just a 3D model and hitbox.

 

You obviously also need the atmosphere to also be curved (so assuming uniform temperature, lines of constant pressure would be curved instead of flat - if that makes sense).

 

The rest of the forces IMO are less critical, but certainly important, but these are more to do with the Earth's rotation and not necessarily just from being a sphere.

 

Converting our current maps to be shaped like the image I posted above however, is a whole other story, and I don't know how easy it would be to convert whatever equations DCS' uses for motion to be converted for a spherical Earth system, using spherical coordinates, even if the transformation from 3D cartesian into spherical coordinates isn't that complicated.

 

5 hours ago, jcomm said:

Some of the major advantages of modelling a geoid have already been mentioned in this thread.

 

The main advantage is accuracy, the maps are more accurate, and you don't have distortion that's inevitable on flat maps trying to replicate a spherical surface (especially as maps get larger).

 

You've also got realistic LOS (I'll ignore refraction though), so for instance it would be possible to see just the tops of ships further out on the horizon, you also wouldn't have to use the workaround DCS currently uses to replicate LOS accounting for curvature, on a flat map.

 

5 hours ago, jcomm said:

I would just like to add that I do believe it is not rocket science. Microsoft Flight Simulator ( since version 5 ), X-Plane, Flight Gear, Aerowinx PSX, ELITE IFT, etc... are all using geoid representations of the Earth, with the associated benefits regarding for instance navigation, wave propagation for detailled non-satellite communications and instruments like those used these days, etc...

 

Agreed, and far from it. At the very basics of what's absolutely necessary you only need to have a curved map (just 3D modelling essentially) and have the direction of weight be radially inwards - which is fairly simple trigonometry.

 

The rest is more to do with the rotation of the earth, though even then the calculations aren't that complicated (especially in comparison to flight dynamics modelling).

Edited July 25, 2021 by Northstar98

[Anatoli-Kagari9]

BTW, both DCS and IL2 have the Channel maps, so, sooner or later they'll probably add to  their assets the V1 an V2 rocket bombs, which would  certainly benefit from a proper implementation of a curved Earth...