FSX Resample Creating Problems

[benclark 0]

I've just started making some mesh scenery for FSX using the FSX Resample program from the SDK. This is compiling and working fine however many files which are perfectly normal DEM's (SRTM v4.1) with no peaks are somehow being miscompiled by Resample as once it's finished they have suddenly gained a number of spikes often 20000ft in height or pits of a similar depth. I don't know what's happening here, Resample should only be turning the DEM file into a BGL and not changing the DEM so why it's leaving these spikes in the finished BGL file I don't know but needless to say it's annoying. Does anyone have any ideas on what I could do to stop this?

[meshman 109]

My experiences with the FSX version of the Resample tool are all positive. If there is a problem it is generally GIGO based; garbage in, garbage out. It only reads the data and converts to a format that FSX can use, it does not alter the underlying data. Or at least I have never seen it do that.If you have some specific areas that can be compared, that would help. But Resample results will only be as good as the source material. And that can vary greatly.

[benclark 0]

Ok lets start with an example. SRTM V4.1 tile srtm_38_12 in GeoTiff format. Opened using Microdem and then Edit>DEM Holes>Missing data to sea level. That fixes the sea. File>Save DEM>GeoTIFF and saved as srtm_38_12.tif in the source directory ready for FSX Resample. Nothing else is needed as it's already in WGS84 format.INF file contents[source]Type = GeoTIFFLayer = ElevationSourceDir = "SourceData"SourceFile = "srtm_38_12.tif"[Destination]DestDir = "Output"DestBaseFileName = "srtm_38_12"DestFileType = BGLLOD = AutoUsing this INF file drag and drop onto Resample to get it started and I get a good 6MB sized BGL file at the end. Here's a link to it - http://realbigtree.co.cc/files/srtm_38_12.bglUsing TmfViewer you can visibly see the peaks, they are more like noise that appear every now and then. I know the source file is not the issue, the V4.1 files are "clean" and nothing in the source goes above 4024m. The height of Mount Cameroon is 4040m so this is a pretty good DEM considering it's a 90m resolution DEM! Could perhaps I change something or add something to the INF file? I've been leaving LOD at auto as it automatically includes all LOD's from 0 to in this case 9, built in "buffering" as I believe it's called.Everything else in the BGL's I've made looks superb, fantastic detail compared to the default FSX scenery so these peaks are really annoying! Hopefully you can help. :-)

[meshman 109]

I made one small change for the INF, but it would not have an effect. I have a template INF that sets compression level to 97, instead of 100 and it makes smaller files. Other than that, downloaded the 38x12 file, loaded into Global Mapper, exported out telling it to fill any little gaps and compiled.So let's compare the results, briefly. Zooming in on your file I can see the spikes. Nothing on mine. Take the location 3.655002Lat x 8.610368Lon your file shows a value of 29090, mine shows 5. Mine shows none of the spikes that are present in your file.The file that you downloaded is all set to run through resample. If you do that and look at the resulting BGL file or check it in-sim, you'll probably not see any problems, for the most part.I'm taking an educated guess, in that Microdem is having difficulties with the negative elevations and that's where the spikes are coming from. The INF file can easily leave out the negative elevation data by using this type of entry under the Source section;MinValidValue = 0

[benclark 0]

Ok I took the default srtm tile and ran it through resample using your MinValidValue addition to the source section. It did flag up a warning - TIFFReadDirectory: Warning, Unknown field with tag 42113 (0xa481) encountered. - but compiled ok with a slightly smaller file. Checking it in the viewer showed no peaks (that I can see) however the ocean is pure white and has a value of 10 (which is odd as by default 3DEM gives the sea in this tile a value of -46) in the bar at the bottom of the screen. I can't run it through GlobalMapper first (as I lack $350 to pay for something I'm only starting out in). Not putting it through Microdem has now it seems cured one problem but created another lolJust checked it out in FSX too and this new file doesn't have the peaks but something is really screwed as the airport is now sitting on an platform. Either the original airport elevation is out or something has gone and upset the DEM nicely. Checking that in ADE confirms, real airport 10m above sea level, FSX default 159.72m! How the hell does MS screw that up so badly. Eek! To fix that I know it's not just a case of altering the airports elevation and making a new bgl file in ADE (an AFCAD) as I just tried that and that made things even worse looking, a floating runway and an platform still present! So how do I get this right.Thanks for helping me, this means alot as I want to be able to do this so badly and I'm learning all the time!

[meshman 109]

One of the quirks of TMFviewer is that whenever you transition to an area of "nothing" it retains whatever elevation reading was last valid. The only way to check the water area to be sure it's at zero elevation is in-sim. And the error warning on the TIFF file is nothing to be concerned about.With a lot of terrain related work in FSX the process is 1.) remove the old and 2.) put in the new. If you need to change an airport's elevation you must change the flatten that the airport sits on. Remove the old and put in the new. Different tools have their way of working through the process. I prefer to do terrain based work with SBuilderX. There are tutorials here in the file library by Luis Feliz-Tirado that I highly recommend.

[benclark 0]

Thanks, I just tried that in TMF and see what you mean about it's quirk regarding empty values. I'll take a look at SBuilderX, heard about it before, didn't think I'd need to start doing flattens and new airport AFCAD's as part of a mesh project, this could take me a long time to achieve my ultimate goals lol.If I could extract one last piece of knowledge from you (for now lol) I want to make use of the Canadian GeoBase CDED data to build a really accurate Canadian mesh. I know FSX Resample needs everything to be in WGS84 datum, considering I now know Microdem screws things up (fairly royally) it seems without so much of a hint I wonder what would be the best program to open, merge, convert datum and resave these files with? It needs to be free too. Is there also anything else I would need to do to the files? I've tried converting it before using Microdem and all you get is a complete load of garbage out of Resample even though in Microdem it looks fine.Thank you so much for all your help!

[benclark 0]

Ok I've tried making a flatten and it worked but didn't do what I want. I purposefully made it larger than necessary so I could see it's affects and while it did flatten the terrain, it didn't flatten the platform the airport is sitting on. The new AFCAD I created using ADEX also has it's altitude set to 10m so that shouldn't be causing the problem, any ideas? I've attached images of my scenery, both with and without the flatten. Removing my own AFCAD makes no difference to the picture.With Flatten - http://farm5.static....737deaa_b_d.jpgWithout Flatten - http://farm5.static....253e89e_b_d.jpgBoth include my mesh which can clearly be seen to be lowering the terrain (as it should) and making Sao Tome look alot better in the process, I just need to get this airport down about 600ft!Edit - Here's the default scenery - http://farm5.static.flickr.com/4105/5060075028_2d9369cb4d_b_d.jpg

[meshman 109]

Quoting a wise old man "Remove the old and put in the new.". Did you exclude the default airport flatten area? Once FSX encounters a flatten command for an area, it ignores subsequent commands. That's why your larger area flatten does work all around the perimeter, but not where there is an existing "airport_background_flatten".For converting source to the format that FSX requires you might look at Map Window, but I've never really worked with it. Otherwise, FW Tools would work, but... it's a command line (DOS window) driven application. Some people aren't familiar with the old style of working with computers. Us old people cut our teeth on DOS and can still remember some of the techniques. :(

[benclark 0]

Ah so in theory if I change the AFCAD and then just create a bgl file with an exclude in it to get rid of FSX's default flatten then I wouldn't need a flatten of my own as the mesh would be correct and the AFCAD would take care of the rest? Next question, how exactly do I exclude the default flatten, unless I'm missing something I can't even see a default flatten in SBuilderX???I've appended the correct file for this area 0603/cvx4931.bgl and I still can't see any default flattens, excludes or anything else? I've read the tutorial by Luis but that talks more about a complete rebuild than simply an update to an existing area and doesn't make everything very clear.