Emilian wrote > > On Saturday, February 23, 2013 07:08:41 Renk Thorsten wrote: > >A lot of stuff, mostly deflecting the discussion to other irelevant > >points > > > > * Thorsten > > While I should know better than to answer to this, as it will again get > deflected to other areas, let's imagine ourselves a simple scenario: > > Let's say I'm an average user with a 32bit system, I can barely find my way > through the maze of menus and dialogs flightgear presents to me, and I want > to use this more advanced weather simulation engine. After I accidentaly > find out how to enable it (it's hidden under a rather confusing radio-button > selection "Model overall weather conditions based on metar"), great, select > "Fair weather" scneario, Apply, OK, let's go flying. > I muck around, wonder at the nice sky/clouds, notice that my visibility > improved somewhat, then bam after 15 minutes flightgear crashes, uhm.. > oohh, why did that happen? That didn't happen before? > All I did was change the way the weather is interpreted... What's wrong > here??? > > Well, now let's see what actually happens in a default flightgear instalation > (all settings are from preferences.xml, and Environment/local-weather- > defaults.xml) > ->trees are enabled by default > ->default visibility with "Fair weather" is ~16km local weather comes in > ->and sets a default value for max visibility of 120km > (o.O), ok, that's a bit far, but in practice I see that's actually hovering in the > 40km range (+-10km based on altitude). (roughly 3x more than the default) > > So in the default scheme we load 9 tiles at startup, then we keep loading tiles > in the direction we're traveling, and those initial tiles remain resident in the > tile cache for a while (in case you decide to double back). > But let's stay with the startup condition. when you ramp up the visibility to > 40km you demand 3 extra "rings" of tiles to be loaded. That would give you at > least 69 tiles loaded (81 if the "rings" are square). So that's an instant increase > of 7-9x the memory requirements of the terrain + objects + trees (tres being > the largest contributor here), just because you click an option that says it just > _interprets_ the METAR string differently. Do you think that's an expected > result? I don't. > > Well, our average user might have read the manual, might have mucked > about with the visibility setting before, and he remeber that all things being > the same, visibility is what impacts performance/memory the most, so he > decides to try again, this time trying to use z/Z to limit how far the visibility > goes, maybe he gets lucky and it won't crash again, but he's in for a surprise... > z/Z doesn't work... > > You might argue that he should know better, go into the advanced settings > dialog, figure out what all those sliders and selection boxes do, etc, etc... > But remeber, our user is an average one, he wants things to just work (with > time, he might find a use for the more advanced configuration stuff, but for > now he's not interested, he just want to click something, and be done with > it), The z/Z case above might be a lucky one where he might have read the > manual. > > The problem is not with "Advanced weather" in itself, the problem is in the > details of a part of it, themost important part from the user POV. Your > approach might work, given unlimited resources, but as it is Flightgear has to > run on a variety of puny little desktop/laptop machines. You have already > implemented half of the control, is it so hard to implement the rest and > provide a system that's consistent with the rest? > Yes it breaks the "real world" scheme, but this is a simulation, we lie, carefully > crafted lies, that give a global impression of truth, of copying the real world > behaviour, but in the end they are lies. Fog/view-distance is one of those > lies, they need just be plausible, not a faithful representation of the real > world (and a faithful representation of the real-world is practically impossible > given the current state of the technology). > > You are comfortable with abdicating from that when it suits you, but where it > really matters you defend the "minute detail faithfull representation of the > real world scheme" vigorously... Don't you think thre's something amiss > here? > > As someone said in another thread, there are various techniques that are not > constrained by the "real-time" requirement, that do a pretty good job of > giving you "real" results, but their place is not here. Here we have to do our > best to trick the mind, while doing that as fast as possible, with a reasonable > usage of resources. Just because you can set visibility to 1000km doesn't > mean you should, just because you can shove a lot of data into a shading > scheme and get back "photoreal" results doesn't mean you should, if said > results reduce performance, increase the probability of running out of > memory, etc. > > You'll argue again with the IAR as an example. Well, take a look at those > numbers again, and you'll see that for the amount of detail it presents to the > user it uses ~0.66 of the memory used by the bare terrain. I don't think that's > unreasonable, others might think differently. (I could have very well > modelled every rivet, nut and bolt on it, I didn't, why? because there are > pretty good techniques of faking that, with plausible results. If you look really > hard you notice that the detail is all fake, that the reflection has nothing to do > with the actual environment etc... but that's irrelevant for the normal use > case) > > You look at view-distance/fog just as an atmospheric phenomenon, that you > think should be represented verbatim, well it's not. It's not just that in any > case, and if for it to fulfil all its roles you need to abdicate from the verbatim > aproach, well then I'm sorry but my opinion is that you should. > I never claimed that it's the only resource management device, I only claimed > that it's role is much more than just visual cue to the environment, and that > role should not be underestimated, or thrown aside... >
I'm probably a day late and a dollar short here - but try as I will so far I've failed to find a visibility slider under environment->weather. It's probably staring me in the face - but could someone point it out to me? Vivian ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://p.sf.net/sfu/appdyn_d2d_feb _______________________________________________ Flightgear-devel mailing list Flightgear-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/flightgear-devel
