how much realism do we need?

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topcomer
Posts: 32
Joined: Thu Sep 21, 2006 1:53 pm
Location: sweden but italian

how much realism do we need?

Post by topcomer »

Hi everyone!
I'm a newbie of the forum and I'm developing a physics engine as my degree thesis.

But my question now is not regarding the thesis (or maybe not yet since I'm in the very beginning but in the future it will certainly happen), is only about sims.

I was discussing with some virtual drivers complaining abt the physics of the last driving sims, speaking and making 'em understand a little bit more about mathematical models, when it came into my mind a question: do we really need a state-of-art realism?

if we think abt cfd or structure mechanics, then FEM is the king method in order to have high precision in the results.
if we instead think abt fly-by-wire systems, they are not based on a physics engine but on feedback atuoregolating system which with a simpler model - I guess comparable with the engine of plane sims - is able to give a description enough accurate to control the vehicle.
maybe I have a bit of confusion inside my brain, but does this mean that too much realism (which maybe we dont have yet but we'r approaching to reach) in sims is a waste of resources?

hope to see your opinions
alessio
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Erwin Coumans
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Re: how much realism do we need?

Post by Erwin Coumans »

topcomer wrote:Hi everyone!
I'm a newbie of the forum and I'm developing a physics engine as my degree thesis.

But my question now is not regarding the thesis (or maybe not yet since I'm in the very beginning but in the future it will certainly happen), is only about sims.

I was discussing with some virtual drivers complaining abt the physics of the last driving sims, speaking and making 'em understand a little bit more about mathematical models, when it came into my mind a question: do we really need a state-of-art realism?

if we think abt cfd or structure mechanics, then FEM is the king method in order to have high precision in the results.
if we instead think abt fly-by-wire systems, they are not based on a physics engine but on feedback atuoregolating system which with a simpler model - I guess comparable with the engine of plane sims - is able to give a description enough accurate to control the vehicle.
maybe I have a bit of confusion inside my brain, but does this mean that too much realism (which maybe we dont have yet but we'r approaching to reach) in sims is a waste of resources?

hope to see your opinions
alessio
Physics in games should be serving FUN in the first place, that's my opinion. If a unrealistic physics model gives a lot of fun, that's fine. See Rockstar's Grand Theft Auto, Vice City: the driving model is totally unrealistic, with probably animation causing the cool cornering. But it is a lot of fun (in my opinion, and given the massive sales others share that opinion ;-)

However, if a realistic can give emergent behaviour, which becomes fun too: the programmer never intended to program the effect explicitly, but it emerged from the realistic complex model.

One more thing: The mapping towards your model makes a lot of simplifications as well, so even an ultra-perfect implementation of that model is not good, because the model was not choosen properly. Using a rigid body to simulate a car chasses is not good for realistic collisions: instead of deforming, the chassis would bounce unrealistically. Even if you have the perfect rigidbody simulation. So not only the implementation of the model, but also the choice of appropriate model is important.

So I think they are somewhat independent, although in practice the game designer wants to influence and control the 'fun' factor in some way. This control can be done by faking the system, but also by tweaking un-intuitive parameters in the FEM model. Most game designers don't know the relationship between say a FEM stiffness parameter, and how the car will perform in corners: it is a non-linear function.

This is a complex function with many input variables, and one main output variable: FUN. Simpifying the function and/or number of inputs (less realistic) might make this function easier to control.
topcomer
Posts: 32
Joined: Thu Sep 21, 2006 1:53 pm
Location: sweden but italian

Post by topcomer »

Thanks for the reply!
I wasnt thinking only abt games but also to professional plane simulators. Do they actually use something as sofisticated as FEM?
And if not, is it worth to reach that grade of accuracy?
what I mean is that a fly-by-wire is able to control an aircraft, maybe considering it a simple multibody object, even an human who interact with a simulator does not need more to have a realistic feeling (and with this I mean that even a big increase in accuracy does not give more realism).
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