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madmat

HGT-file for SRTM2BGL

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HiI've looked for mesh-data for Greece. I've tried the palace recommended in the SRTM2BGL ReadMe-file... ftp://edcsgs9.cr.usgs.gov/pub/data/srtm/I wonder if its the right place for mesh-data when the country is Greece? Looking in the relevant folder for Greece (E020N40) I find a lot of different file-types (extensionnames are DEM, DIF, DMW, HDR, NUM, PRJ, SCH, SRC, STD, STX) and I wonder where the .HGT file which is needed for SRTM2BGL is located?Cheers Lars

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Hi Lars:I think you might have ended up in the wrong directory; the descriptions sounds like you're looking at the SRTM30 tiles, which are very coarse (30-arcsec or ~900m). You need to look in the Eurasia subfolder and then locate your tile of interest. Actually, you need at least two tiles for SRTM2BGL to work.Cheers, Holger

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Hi Holger:Thankyou - I will look at the Eurasia subfolder. Do you know how the files there are organised? With my sporadic islands having this Image extent...N 39.51W 23.35S 39.0199818057971E 24.3399956992576Which two files will I need for my SRTM2BGL program?Cheers - Lars

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Hi Holger!Thanks a lot for your patient help. As you can see I have posted a new question (will that kid never stop asking...?). I've tried to make the BGL-file but nothing shows up in FS2004 allthough I can see the mesh data in TMFviewer. Cheers - Lars

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Hi Lars,I did a little mesh around your area, I tried to use Blackart to flatten the sea, and it worked fairly well I think. I used the SRTM fill program before I moved it all into srtm2bgl and the mesh looks better than the default. The area is N33 E 22 up to N40 E25, is about 9 Meg and I'll upload it to Avsim when they get up and running again, if you like.Dwayne

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Hi Dwayne!Thanks for your answer and offer! >the SRTM fill program before I moved it all into srtm2bgl and>the mesh looks better than the default. The area is N33 E 22>up to N40 E25, is about 9 MegAre these mesh data better (more accurate) than the data i downloaded from the link given by Holger earlier in this thread?>I used the SRTM fill program before I moved it all into srtm2bglI do not know this SRTM fill program. Is it a good tool?I would like to hear a few words about your way of optimizing the default MSFS areas. I'm trying to work something out myself by the help of all the clever guys here on the AVSIM Forum! And I will be glad to give you my "recipe" on working out a more precise island if you are interested!Best RegardsLars

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Lars:I guess you are needing more detailed infoabout convertion SRTM to BGL.Did you have success about that greek islands?Contact me by mail stentor@terra.com.br.Will be glad to send to you step by stepprocedure.CheersCelso Junior

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hello Lars,http://www.3dnature.com/ is the address of a website that has the SRTMFill program that Holger found and recommended in another thread. This works very well to fill voids in the hgt files. You could also use Blackart which can do a fill or merge other data to help fill the voids too.I used the same SRTM data that Holger pointed you to. I also read your step by step process that you are going to use and commented a little there. I have not really dived into changing coastlines and landclasses yet, I am just happy to get a good mesh base to start with :)Dwayne

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Hi all:Dwayne, I'm afraid there's a misunderstanding. In the thread you refer to - http://forums.avsim.net/dcboard.php?az=sho..._id=1459&page=2 - I mention SRTMFill but I don't (!) recommend it. Like MicroDEM, 3DEM, and SRTM2BGL it uses a simple linear algorithm which leads to very strange effects in mountainous areas, particularly with larger holes. The first image below is part of a tile in Patagonia filled with SRTM2BGL (20 passes) and the second image of the same area filled with SRTMFill: not much of a difference.For areas with less relief and smaller holes, such as central and eastern Canada, any of the linear interpolation algorithms might work well. I just want to emphasize that for high-relief areas Blackart is clearly the best option. Since the newer versions (currently version 3.71) support batch processing it's easy to run the time-consuming LSQR interpolation over night or in the background.Cheers, Holgerhttp://forums.avsim.net/user_files/69121.jpghttp://forums.avsim.net/user_files/69122.jpg

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Holger, Thanks for clearing that up, I misunderstood and thought that SRTMFill provided a good alternative. I can see in your example the odd clipping and see that for such it would not be very good. I did use it on Manitoba and Saskatchewan and as you say, flat land is not a problem :)I'll read up more on Blackart and see how I can use it for higher areas.Dwayne

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