Mesh Creation for the Dumb!

[stdtoast]

Greetings! I come seeking advice from you, considering my three weeks of searching FSDev has shown me you are the person to go to when a mesh question is involved. The SDK is not making much sense to me and from what directions and tutorials I have followed from the FSDev website, I have been unable to successfully compile any mesh at all regardless of data type or sample size.

My current project circles on improving the hills that show on the Runway 26 approach and Runway 17 departure at KDXR. These are very dramatic areas of land that make for a stunning real life experience, but one that leaves me feeling let down in the sim. My current data set consists of a BIL data file from the USGS Seamless server, which covers just the hill on the Runway 26 approach. This is comparably a small file which I wanted to try compiling to get results.

I set up my INF file and data file in a "Test" folder on the desktop as is mentioned on FSDev, and edit the INF file accordingly. This is what I have:

[Source]
Type                = Raw
Layer               = Elevation
SourceDir           = "."
SourceFile          = "45500667.bil"

[Destination]
DestDir             = "."
DestBaseFileName    = "Danbury_Test"
DestFileType        = BGL
LOD                 = Auto


The file is then run through a command line accesses Resample, and I receive three errors.

1. "Number of rows and columns must not be zero"
2. "Unable to open data source"
3. "Failed to create data source"

This same problem has occurred using both BIL data, as well as GeoTIFF. Heeding warnings, I did check their formats in a trial version of Global Mapper, and both are in the correct constraining formats. All of my data is SRTM 1-Arc Sec data. I am developing for FSX. I have also used an INF file coded for the same project, as such:

[Source]
Type                = Raw
Layer               = Elevation
SourceDir           = "45500667"
SourceFile          = "45500667.bil"

[Destination]
DestDir             = "45500667"
DestBaseFileName    = "Danbury_Test"
DestFileType        = BGL
LOD                 = Auto

Same outcome.

Alas, I am therefore stuck, and my three weeks of fiddling with the SDK and this process have left me frazzled. If you could offer some wisdom or point out something I am missing, I would be grateful. I have some larger projects shelved until I can figure this out, then hopefully I can recreate the airports I have flown into and out of more faithfully.

Thanks!

[scubakobe]

Hi,

There are quite a few things that could be causing the problem.

First off, double check that your BIL file is in WGS84 projection. Direct from USGS it will be NAD83 and must be converted.

You also should move the Test folder to My Documents. The move to My Documents will be reflected in the edited INF file below:



[Source]
Type                = Raw
SourceDir           = "C:\Documents and Settings\XXXXXX\My Documents\Test"
SourceFile          = "xxxx.bil"
Layer               = Elevation
nCols               = xxxx
nRows             = xxxx
ulxMap            = xxx.xxxxx
ulyMap            = xxx.xxxxx
xDim               = xxxx
yDim               = xxxx
BandLayout    = BIL
nBands          = xxxx
SampleType   = xxxx


[Destination]
DestDir             = "C:\Documents and Settings\XXXXXX\My Documents\Test"
DestBaseFileName    = "xxxxx"
DestFileType        = BGL
LOD                 = Auto



You can find the number of columns and rows from Global Mapper. The ulxMap and ulyMap are the upper left coordinates of the mesh - also can be found with Global Mapper.

xDim is the pixel width in degrees and can be calculated by:
[ (Pixels Wide / (Western border longitude in degrees - Eastern border longitude in degrees) ) ]

yDim is only slightly different:
[ (Pixels Tall / (Northern border latitude in degrees - Southern border longitude in degrees) ) ]

Calculating xDim and yDim can be confusing at first. If you need help on that, just supply me with the data you see in the equation.

BandLayout has many possible values, but from my experience with BIL format, it will either be UINT16 or SINT16 which stands for 16 bit unsigned integer and 16 bit signed integer respectively. You should be able to check that with Global Mapper.

You mention using a GeoTIFF. In FSX, this IS the way to go. If possible, I would convert your BIL file to GeoTIFF. Why? Take a look at how your INF file will look if you used GeoTIFF:



[Source]
Type                = GeoTIFF
SourceDir           = "C:\Documents and Settings\XXXXXX\My Documents\Test"
SourceFile          = "xxxx.tif"
Layer               = Elevation

[Destination]
DestDir             = "C:\Documents and Settings\XXXXXX\My Documents\Test"
DestBaseFileName    = "xxxxx"
DestFileType        = BGL
LOD                 = Auto





Much easier isn't it? If you can, I'd highly suggest using GeoTIFF for mesh and photo scenery in FSX.

Try using the updated INF file I gave you (Editing the xxx's with specific info of course). If you have any further questions feel free to ask.

Hope this helps!

-Kobbe

[stdtoast]

Thanks!

I re-cheched the BIL, and after doing some more clicking around in Global Mapper, found I was looking at the wrong format information. At the suggestion of a friend, I re downloaded the data as a GeoTIFF, converted to 32-bit floating point WGS84, and recompiled. Had another error till I corrected the file naming, then it worked perfectly and spit out a nice tidy BGL. So I did have incorrect data, and an incorrect INF.

But now my next issue is the mesh itself. I don't know if there are specific settings to fix this, but I have attached a picture of the issue as I find it hard to explain.

img37.imageshack.us/img37/9844/treemeshissue.jpg

There are these random, dense tree patches that do not conform to the mesh itself. Reading the SDK mentioned nothing about this, and they're pretty ugly. I would rather not have them. They look like tropical trees in a climate where the deciduous forest is the norm.

The two other small issues I ran into. One, sharp changes in mesh elevation. I know the area around KDXR extensively, growing up in Danbury itself for 13 years of my life. The land in some places is not as sharp and dramatic as the mesh makes it look. The SDK mentioned FractionBits, and I was wondering if this would have an effect on that outcome. Perhaps I can smooth it out some, if not eliminate it. This also extends to the boundaries of the airport, where on one end it meshes quite well, except for a nearly 10 foot rising ridge that the airport seems to sit on. I checked the altitude at that spot with the USGS Server, and crosschecked airport altitude in ADE and AirNav (FAA Diagrams). Everything is as it should be, but there is still that drastic of a difference.

The second issue, is more of a curiosity. Is it possible to layer landclass one on top of the other? Another scenery I previously completed can use some touching up on the surrounding mountains and hills, and rather than mesh the entire area, only some need work on them. Problem is I do not see anything about alpha-channel masks for mesh working, and the USGS Server only allows rectangular download areas. If I were to overlap some corners a little bit, would there be an adverse effect, or would it be prudent to just mesh the entire airport surroundings?

Just the fact that this process is working for me, is a gift in itself. Thank so much for the push in the right direction! Danbury, despite its small faults, has some nice looking approaches now, and it's looking much better.

[scubakobe]

I'm glad you were able to make it work.

Not sure what is happening with the autogen. The fact that it's floating is because the terrain is steep, but if it's tropical autogen in a deciduous forest then the landclass must be wrong.

As for the sharp points in the mesh, sometimes that can't be avoided. Have you tried working with FractionBits? That may help.

The 10 foot ridge is most likely due to the default airport flatten. If you take a screenshot of the problem I may be able to figure out if that's the case or not.

I don't understand what you mean about layering landclass. Are you talking about mesh, or the actual ground texture/landclass? To touch up one area with more refined mesh, it would be easier to just create another mesh BGL for that area.

There is a way to make a hill\mountain in Gmax but it's a LOT of work for what you're doing.