Hi Yves, On 09/15/2012 12:33 PM, HB-GRAL wrote: > Am 14.09.12 17:19, schrieb Eric van den Berg: >> For some time now I have suspected that srtmchop does not do its job >> correctly. Two reasons: >> 1. At ELLX the VOR LUX, although placed at the correct lat/lon is >> located at the foot of a hill which if it would be there in RL would not >> improve nav signal reception. (ref: >> http://www.emmerich-j.de/EDDF/EDDF-ELLX.zip) > > Hi Eric > > As I understand this is "just" a slightly misplace VOR, isn’t it? You > can get the right location and submit this to xplane data source. Then > the right location will come to flightgear scenery data automatically > once, and will be available also for custom scenery builds. > http://data.x-plane.com/faq_designer.html > No, I think you misunderstand. The VOR is placed correctly. The Terrain is wrong, the hill is shifted to the south. That is how my suspicion of false elevation was raised in the first place.
>> 2. The north border of the geotiff files is 0 elevation over the entire >> west-east line in the output files (*.arr.gz) >> >> So I experimented a bit and to make a long story short I wrote something >> that handles the data correctly. Called ascchop as it chops *.asc files >> (from http://srtm.csi.cgiar.org) and not the geotiff-s (same data >> though). Only works on linux and as I only know a bit of fortran written >> in that language. >> Let me know if interested. >> >> So it looks like srtmchop somehow 'forgets' the entire south border and >> shifts all elevation data 0.0008333 degrees south. Of course when it >> gets to the north border, no data left and makes it all 0. >> >> Cheers, >> >> Eric > > I had a look to srtmchop once and I guess there are also other > problems with this "chopper". I don’t use it because all my tests > failed, I’m still using hgtchop which works like a charm. AFAIK > srtmchop was mainly thought for CGIAR data and is a side project, > hooking on CGIAR data it will produce scenery data that can’t be > distributed under common used FlightGear scenery data license (GPL). > 1. I do not see why CGIAR data derived works cannot be published under GPL. They just want to be mentioned in the credits and put no restrictions on derived works what so ever. Therefore I (or anyone else) using the data can put it under any licence they want. But I will sent them an email to clarify. 2. Are you sure current official scenery is published under GPL? There are certain things you need to do for that to happen. Like (quote from GPL v2): "For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights." When I download official FG scenery, be it from the homepage or terrasync or I use it, there is never any notion that it is under GPL and neither are "these rights shown to me". In my opinion the prerequisites of the GPL v2 license are not met, so it simply is not GPL'd. > You can pull terragear source at http://www.gitorious.org/fg/terragear > and send a merge request to try to add your ascchop code. To be honest > I don’t know if it’s good practice to have this written in fortran and > have it available for linux only, but maybe you can send a merge > request there and ask for review? And maybe you can try to improve > srtmchop also, so your work comes to tools already there? > > -Yves > > Well good point. But I only know (a bit of) fortran, so I am unable to improve srtmchop, sadly. The question is if we want to have a C program that we know has a bug or a fortran program that works. I will try and see to make ascchop work on windoze also as good as I can, but as I do not have windoze, I will need a volunteer to test it! Eric ------------------------------------------------------------------------------ Everyone hates slow websites. So do we. Make your web apps faster with AppDynamics Download AppDynamics Lite for free today: http://ad.doubleclick.net/clk;258768047;13503038;j? http://info.appdynamics.com/FreeJavaPerformanceDownload.html _______________________________________________ Flightgear-scenery mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/flightgear-scenery
