Re: [Flightgear-devel] Real weather fetch stops FG from starting
On Monday 15 Aug 2005 08:55, Erik Hofman wrote: Lee Elliott wrote: I've just been having a problem with FG failing to start when real-weather-fetch is enabled and the METAR data is too old This problem has been reported before. I (or someone else) still need(s) to take a look at it. I don't think it's that much of a problem to solve though, probably just a matter of incrementing the error counter it the right location. Erik I sort of got around it by increasing the metar-max-age-min entry in preferences.xml from 2 to 4 hours. I figured that this would let FG accept out of date reports but still use up to date ones where available. Seemed to work. LeeE ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Real weather fetch stops FG from starting
Lee Elliott wrote: I've just been having a problem with FG failing to start when real-weather-fetch is enabled and the METAR data is too old This problem has been reported before. I (or someone else) still need(s) to take a look at it. I don't think it's that much of a problem to solve though, probably just a matter of incrementing the error counter it the right location. Erik ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
[Flightgear-devel] Real weather fetch stops FG from starting
Hello all, I've just been having a problem with FG failing to start when real-weather-fetch is enabled and the METAR data is too old At least, that's the message I'm getting when I set the log-level to warn. I thought FG would try for a while and then start with real-weather-fetch disabled if it hit any problems with it. I left it running for several minutes, waiting for it to start but all I could see were the error messages scrolling up in the terminal window and the repeated attempts by FG to get the data across my network. Would it be possible for FG to ask the user what it should do at this point? LeeE ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Real weather fetch
On Wed, 29 Dec 2004 13:16:48 -0600 Curtis L. Olson wrote: I know different people will have different opinions on this, but I feel that simply interpolating over time to the closest data is just as good as anything. Interpolating spacially between the closest 3 stations is attractive, but remember this data is already starting to get old by the time we get it so we will never be exactly correct with current conditions. [ snip ] Personally, I think it would be a *lot* simpler, and arguably just as accurate to do a temporal interpolation towards the latest data at the closest weather station. Another issue is the fact that the data available from the METAR station seems sometimes *very* old (e.g. a day or more). I've flown (in FlightGear) around a metropolitan area where I know exactly what the weather's like (e.g. clear skies), and found it change from roughly correct weather to something *wildly wrong* (e.g. overcast down to 900 feet, which it was like earlier in the week but definitely not today) to something correct again (back to clear skies) as I fly 5 miles in a straight line over the metro area. So instead of spatial interpolation, one might consider weighted spatial averaging (e.g. a gather scheme with a broad Gaussian kernel or whatever) to lessen the effect of anomalous stations in densely sampled areas. Lot's of fun to be had if someone had the time to play with it ... I used to do stuff that bears some similarities to this for a living. Unfortunately, it was in FORTRAN. Heh. -c -- Chris Metzler [EMAIL PROTECTED] (remove snip-me. to email) As a child I understood how to give; I have forgotten this grace since I have become civilized. - Chief Luther Standing Bear pgptjRd60lF7A.pgp Description: PGP signature ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Real weather fetch
David Luff wrote: I tried out the real weather fetch option for the first time yesterday. It's absolutely excellent! It just worked, with no setup or bother, and gave the correct weather in Chicago according to the forcast, and the correct weather in Nottingham according to the view out of the window. I'm afraid I can't recall who is responsible for this - I can't always keep up with all the list traffic, but whoever it was - thanks :-) Melchior did the fetching code, Curt and me implemented most of the rest using the Environment class of David Megginson. So basically everybody did some wok on it :-) Erik (I'm glad you like it) ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Real weather fetch
Dave Martin wrote: The lack of transition can play havoc with the 172's autopilot too (usually delivers you into a spin/stall). Yes, that's definitely one thing to fix. Erik ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
RE: [Flightgear-devel] Real weather fetch
Erik Hofman writes: David Luff wrote: I tried out the real weather fetch option for the first time yesterday. It's absolutely excellent! It just worked, with no setup or bother, and gave the correct weather in Chicago according to the forcast, and the correct weather in Nottingham according to the view out of the window. I'm afraid I can't recall who is responsible for this - I can't always keep up with all the list traffic, but whoever it was - thanks :-) Melchior did the fetching code, Curt and me implemented most of the rest using the Environment class of David Megginson. So basically everybody did some wok on it :-) Yes lots of people helped for example http://jeremy.zawodny.com/perl/Geo-METAR/ http://www.schwarzvogel.de/software-pymetar.shtml Norman ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Real weather fetch
Norman Vine wrote: Yes lots of people helped for example http://jeremy.zawodny.com/perl/Geo-METAR/ http://www.schwarzvogel.de/software-pymetar.shtml This sounds as if you think the METAR data is fetched only once. In fact it isn't, it's fetched ever 30 sec. if the user is closer to a different METAR station than to the previous one, or else it's fetched every 5 minutes or so. Erik ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
RE: [Flightgear-devel] Real weather fetch
Erik Hofman writes: Norman Vine wrote: Yes lots of people helped for example http://jeremy.zawodny.com/perl/Geo-METAR/ http://www.schwarzvogel.de/software-pymetar.shtml This sounds as if you think the METAR data is fetched only once. In fact it isn't, it's fetched ever 30 sec. if the user is closer to a different METAR station than to the previous one, or else it's fetched every 5 minutes or so. Oh .. I am 'quite familiar' with the algorithm used to find the closest airport.efficiently :-) Cheers Norman ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Real weather fetch
On Wednesday 29 Dec 2004 09:26, Erik Hofman wrote: Dave Martin wrote: The lack of transition can play havoc with the 172's autopilot too (usually delivers you into a spin/stall). Yes, that's definitely one thing to fix. Erik I'd imagine a progression between one set of METAR data to the next over 1-2 minutes would work fairly nicely. I haven't quite worked out why the 172's AP is so keep to go vertical during weather changes - sudden baro change perhaps? Dave Martin. ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Real weather fetch
Dave Martin wrote: I'd imagine a progression between one set of METAR data to the next over 1-2 minutes would work fairly nicely. Just a thought: Would'nt the way more 'correct' (TM) solution be to permanently interpolate between the closest three stations - I mean, weather doesn't just start changing after you've already passed half of your way to the next airport ;-) Well, I realize that the most difficult part is not which source of information to use but instead to determine which sort of weather phenomenons are suitable for interpolation between each other - how do you interpolate between cloud layers !? Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -- ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Real weather fetch
Martin Spott wrote: Dave Martin wrote: I'd imagine a progression between one set of METAR data to the next over 1-2 minutes would work fairly nicely. Just a thought: Would'nt the way more 'correct' (TM) solution be to permanently interpolate between the closest three stations - I mean, weather doesn't just start changing after you've already passed half of your way to the next airport ;-) Well, I realize that the most difficult part is not which source of information to use but instead to determine which sort of weather phenomenons are suitable for interpolation between each other - how do you interpolate between cloud layers !? I know different people will have different opinions on this, but I feel that simply interpolating over time to the closest data is just as good as anything. Interpolating spacially between the closest 3 stations is attractive, but remember this data is already starting to get old by the time we get it so we will never be exactly correct with current conditions. Interpolating weather between stations is also a bit dubious because of the potential variability ... it's not a bad way to do it, but I don't know that it is *more* accurate than other approaches. Also, you still have to handle the situation where your station data is updated and changes ... you still have to do some sort of temporal interpolation along with your spatial interpolation. Personally, I think it would be a *lot* simpler, and arguably just as accurate to do a temporal interpolation towards the latest data at the closest weather station. Spreading it out over a couple minutes should be fine (although we may want to impose a maximum rate of change of things like visibility.) Also we need to figure out how to interpolate different cloud layers and coverages. We could fade out the old layers and fade in the new? Or slowly move layers? Or some combination depending on how different the old weather is from the new? Lot's of fun to be had if someone had the time to play with it ... Curt. -- Curtis Olsonhttp://www.flightgear.org/~curt HumanFIRST Program http://www.humanfirst.umn.edu/ FlightGear Project http://www.flightgear.org Unique text:2f585eeea02e2c79d7b1d8c4963bae2d ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Real weather fetch
On Wednesday, 29 December 2004 21:16, Curtis L. Olson wrote: Spreading it out over a couple minutes should be fine (although we may want to impose a maximum rate of change of things like visibility.) However if someone fires up a Mach 10 prototype they may arrive at the new METAR station with the weather still similar to the previous METAR station. e.g. It may have only changed by 30% by the time they arrive at a new METAR station if the rate of change is too slow. Also we need to figure out how to interpolate different cloud layers and coverages. We could fade out the old layers and fade in the new? Or slowly move layers? Or some combination depending on how different the old weather is from the new? Lot's of fun to be had if someone had the time to play with it ... Personally I think the best way is to actually build new 3D cloud layers in transitional zones that are based on an interpolation of the METARS. Fading works but does not look very good - just try it out in FUIII and MSFS to see what I mean. Interestingly enough MS still haven't figured out a way to transition between weather systems nicely and a lot of FS2004 fans hate the way it works at the moment. It's supposed to fade in/out but the transitions are sometimes so quick (METAR stations packed close together) that there's a *flash* and a 50km long cloud front just vanished. :) It's encouraging - in a mildly sadistic sort of way - to see other people battling with the same issues. :P Paul ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Real weather fetch
Curtis L. Olson wrote: [...] Also we need to figure out how to interpolate different cloud layers and coverages. That's exactly the problem I was pointing at. I have started digging through my meteo textbook and it appears to me that presumably more different phenomenons that might follow each other in METAR reports where we might face the problem of not having an unambiguous transitional stage - although maybe they are currently not utilized within FlightGear (there's currently no rain in FG, is it ?), Martin. -- Unix _IS_ user friendly - it's just selective about who its friends are ! -- ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Real weather fetch
On December 29, 2004 04:07 pm, Martin Spott wrote: Curtis L. Olson wrote: [...] Also we need to figure out how to interpolate different cloud layers and coverages. That's exactly the problem I was pointing at. I have started digging through my meteo textbook and it appears to me that presumably more different phenomenons that might follow each other in METAR reports where we might face the problem of not having an unambiguous transitional stage - although maybe they are currently not utilized within FlightGear (there's currently no rain in FG, is it ?), Martin. We should also look into changing the lighting condition according to different types of weather. Perhaps we can check the position of the active camera, and then do the followings: - Make ambient intensity proportional to the density of clouds. - Make diffuse intensity inversely proportional to the density of clouds. - Make light intensity inversely proportional to the density of clouds. Ampere ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Real weather fetch
On Wednesday 29 Dec 2004 00:31, David Luff wrote: I tried out the real weather fetch option for the first time yesterday. It's absolutely excellent! It just worked, with no setup or bother, and gave the correct weather in Chicago according to the forcast, and the correct weather in Nottingham according to the view out of the window. I'm afraid I can't recall who is responsible for this - I can't always keep up with all the list traffic, but whoever it was - thanks :-) Cheers - Dave ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d The --real-weather-fetch is great. You find yourself madly scrambling to look up the local ATIS frequency when you're approaching your destination. It gets very interesting when the weather changes tho as there is no gradual transition so its just *bang* you're there! You also find yourself madly scrambling to look up the local ATIS frequency when you're approaching your destination. Can be quite interesting when you're negotiating the Cotswolds under low cloud and then you suddenly find yourself in a pea-souper ;-) The lack of transition can play havoc with the 172's autopilot too (usually delivers you into a spin/stall). Despite this the weather effects are so good in FG that I always fly with real weather and in real time :-) ps: David you have Mail (taxiways). Dave Martin. ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
Re: [Flightgear-devel] Real weather fetch
Dave Martin writes: ps: David you have Mail (taxiways). OK, great. If they've gone to my nottingham.ac.uk address I won't get them until tomorrow, but I'll make sure I pick them up then. Cheers - Dave ___ Flightgear-devel mailing list Flightgear-devel@flightgear.org http://mail.flightgear.org/mailman/listinfo/flightgear-devel 2f585eeea02e2c79d7b1d8c4963bae2d
