P3D v5 Fun with TIN files

[crushnik]

I think I'm finally getting closer to making sloped airports using TIN files. I am posting what I've come up with so far and hopefully more knowledgeable folks here would be able to point me towards the finish line.

To get the airport bound shapefiles, I open a stock airport in Airport Design Editor to give me the Scenery/####/scenery/cvx####.bgl file I need. I use CVXExtractor to get the FLX airport bound shapefiles, which I have to open up in SceneryBuilderX and export again so it has the proper CRS.

I then import my airport bounds in QGIS, then download the 1/3 arc-second TIFF from USGS that covers the airport I am working on. That gives me a raster elevation file and a vector airport boundary file.

Here is where I am probably starting to veer off course:

I have 10m terrain, which comes from the same USGS files, so a TIN file made from the same source data should be close enough. I have QGIS clip out the raster area so I am only left with airport boundaries. I then turn that data into 1.0 meter contour lines, which I then turn into points. Then I run Delaunay triangulation and get my polygons (see image below).

I am unclear about what process will eliminate the areas outside of the airport bound, or how to turn my project into something that another program (Blender maybe) can turn the data into a triangular polygons that will be used by the sim. Any input would be greatly appreciated.

 

[crushnik]

Ortho4XP supposedly makes TIN files out of elevation data. I wonder if that could be useful for creating sloped runways in P3D?

 

[GaryGB]

Hi Chris:

Are you trying to make sloped RWYs with surfaces that are:

* Perfectly Flat (but not 'level')

...or:

* Bumpy (and not 'level')

FYI: If you use CvxExtractor on default CVX BGLs and output FLX type *.BLN files, you can process the data into ASCII text files, then re-assign Altitudes for the RWY end coordinates, while keeping the RWY ARP position Altitude unchanged.

GaryGB

 

[crushnik]

Door no. 2: Bumpy and not level.

I prefer dirt/grass strips so I wouldn't think it should be too difficult. But that's what I've thought for every scenery idea I've had and I should know better by now.

The easiest solution if you have ortho is to just move the runway or delete it, which leaves perfectly flowing terrain. But I'd prefer to learn how to do it properly if possible.

 

[GaryGB]

Hi Chris:

I am rather encumbered by some commitments IRL recently, but you are IMHO already showing a useful work-flow for TINs.

AFAIK, on a practical basis, it may be best to decimate the triangles of RWY areas for better P3D user aircraft performance, although it is true that a CVX FLX-type airport boundary vector flatten merely pre-emptively imposes its own ground 'shape' onto the underlying gridded terrain mesh elevation data points.

As the CVX vector sloped flatten surface source matches that used for gridded terrain mesh, the CVX airport boundary flatten will blend OK at its periphery.


SBuilderX can export the CVX FLX-type airport boundary vector flatten if you manually decimate the RWY area triangles into a smaller number of triangles.

One may also use a 3D modeling application with a geo-referenced (geo-located) central datum Origin of Axes and import / export to CVX via Arno's MCX:

Flattens from 3D objects | SceneryDesign.org

https://www.fsdeveloper.com/forum/t...x-sloped-flatten-scenery-object-moved.446355/

These methods will allow one to clip the 'displayed' data set to the physical extent of the desired data set to a grid quad if submitted to SDK SHP2VEC


In a GIS application. one can set the altitude for all points outside the airport boundary to -32767 and designate that NullValue parameter value as a "NO_DATA" or "MISSING_DATA" area.


We would normally use this to make a terrain mesh via a SDK Resample *.INF file, so a smaller 'displayed' terrain mesh can be output from a larger data set:

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Terrain Overview

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However, your goal is to make a number of local CVX vector airport boundary TIN surfaces within larger CVX vector FLX-type sloped flatten BGLs via SDK SHP2VEC, so you may prefer to find a semi-automated way to resample / decimate only the RWY parts of the sloped flatten area in favor of more FPS.


To display and test this work-flow, FSX / P3D sliders must be set at 1 Meter or smaller terrain resolution and at 100 % terrain complexity (tessellation).


SBuilderX can convert RWY axis lines into RWY polygons; these objects can then be used to form the CVX FLX-type airport boundary vector flatten ...after you manually decimate the RWY area triangles into a smaller (lesser) number of triangles.

Thus, I believe SBuilderX would be the easiest tool to use for 'manually' deriving RWY polygon areas.


Because RWYs are lines extruded at run time and do not inherently derive from (4) border vertices in native BGLComp XML code, one must otherwise "do the math" to compute N-E-S-W corner Geographic coordinates directionally outward from each RWY central Geographic coordinate and declared RWY length from de-compiled airport XML.

I am not certain if Arno has a utility function in MCX or ScenProc to derive (4) RWY border vertices from multiple RWY axis line coordinates submitted as a sequential input file.

I am also not certain as to whether (4) FS RWY border 'corner' vertex Geographic coordinates are output by Pete Dowson's "Make Runway" utility:

http://www.fsuipc.com/


I hope this info proves to be of some additional help with developing your work-flow for larger extents of coverage.

GaryGB

 

[crushnik]

Flight simulation scenery creation, at least it has been my experience, is more of a problem-solving exercise that I can play with. It has become more about the feeling of accomplishment when I can solve a mystery -- sometimes with lots of help -- than it is about creating anything.

 

[GaryGB]

Indeed, the process of wondering "what if" or "how can" a task be achieved ...may be a primary appeal to many of us at FS Developer more than commerce.

GaryGB

 

[crushnik]

Yeah, as nerdy as this sounds, I find myself looking around at traffic lights as I drive and I ponder different commands and methods I could use to inject stop lights into the sim. Sure, I could manually place them, but it's more fun to watch ScenProc do it for an entire state in just seconds after I have found the right combination of commands.

Scenery design has also given me an even greater appreciation of the outdoors. Hard to wrap your mind around the complexity of clouds for example. There has never been -- nor will there ever be -- two clouds that are the exact same. What an amazing planet we get to live on, right?

 

[crushnik]

Three years later I am just as stuck on this project... I have a digital elevation map that I want to turn into a 3D model where I can either put imagery over it or create polygons with textures for the paint. I can make contours, turn those into points, those into triangles. The data is in WGS84. I go to export anything to Blender and all I ever get is something that looks like a very tall tower.

Ideally I would like to clip the raster on the airport boundary (this is Mesquite, Nevada) so I have a smaller workspace. Given the help I've had previously (thanks Gary) I imagine I am probably just missing one or two checkboxes. Does anyone know where I am going wrong?

 

[GaryGB]

Hi Chris:

I have not yet tinkered with a Blender GIS plugin such as the one by Domlysz, which IIUC works with multiple CRS / SRS projections.

https://github.com/domlysz/BlenderGIS/wiki/27x-Shapefile-import


What would you like to do in Blender at the above cited location which would be distinct from prior workflows ?


Remember, if one makes a CVX FLX airport RWY sloped flatten too "bumpy", it would be a P.I.T.A. to use except with tundra tires.

But a "sloped" FS RWY is definitely more fun, IMHO.


As you stated above, you could drape SDK Resample PR aerial imagery over the area with ground markings baked into the imagery for maximum run time resolution of the BGL.

IIRC, if one made a custom land class ground marking texture to drape onto terrain mesh, resolution is limited to only 1-Meter-per-pixel.


If you wanted higher resolution terrain mesh to better represent the RWY morphology with its ~90 Foot slope SW to NE, and its steep embankments, you could make a SDK Resample custom terrain mesh with limited Geographic extent to locally over-ride FS default terrain.

IIUC, you only want to make a smaller number of local high resolution terrain mesh tiles within / approximate to the airport boundary.

So, during QGIS processing, DEM data can be configured to a desired actual mesh extent by assigning areas outside immediate adjacent Quad extent areas to a NODATA attribute of -32767, which should force SDK resample to show default- not custom- terrain ...outside your assigned airport mesh boundary.

This also effectively keeps BGL size to a minimum as "NODATA" is written to a technically larger extent of a BGLs "coverage" Geographically.


Then one could place airport Start Location points at each end of the RWY as spawn points, but NOT place a "flat" BGLComp RWY object.


https://en.wikipedia.org/wiki/Mesquite_Airport

Geographic Coordinates: 36.833056, -114.055833


Looking at the P3Dv4 default files / objects, I find:

[P3Dv4 install path]\Scenery\0202\Scenery


In SDK TMFViewer, Open dem0202.bgl > zoom to local LOD-9 / QMID-11 Quad > read: File#1718

In SDK TMFViewer, Open cvx1718.bgl > zoom to show local LOD-9 / QMID-11 Quad extents / types of airport polygons


In CvxExtractor, open cvx1718.bgl > extract to ESRI SHP file(s)

CvxExtractor SHP files will be de-compiled as 'warped' EPSG:4326.

One must re-project output SHP data to 'non-warped' EPSG:3857 if used with 3D modeling.


For purposes of submitting final source data sets to P3Dv4 SDK for compilation, all such data must be projected in EPSG:4326

Use of EPSG:4326 data as de-compiled by CvxExtractor works OK if such a SHP is imported for processing via SBuilderX.

IIRC, ScenProc automatically configures working data sets to required EPSG projection during import and export / compilation for P3D SDK.


Just a few ideas.

GaryGB

 

[crushnik]

One must re-project output SHP data to 'non-warped' EPSG:3857 if used with 3D modeling.

I think THIS is the one thing I've been missing! I always work with EPSG:4326. So everything gets converted to 3857 for 3D work, then export to 4326 for compiling into the sim.

I made custom terrain mesh for the entire United States so if I removed the airport flatten and made the runway disappear Mesquite would be pretty accurate, but ground textures would be somewhat blurry from the cockpit. Now I can see if higher resolution textures just for the airport bounds would be better or make ground polys. Everything in life is a tradeoff so none of the AI traffic I program will work unless it's a flat airport, correct?

 

[GaryGB]

...so none of the AI traffic I program will work unless it's a flat airport, correct?

Good question; AFAIK (1) or more latter versions of P3D were supposed to have implemented AI traffic on sloped RWYs.

But, I have yet to see any addon that successfully did so; however that may be because I have made little use of P3Dv4.x.

I'll take a look to see whether there was a further test-of-concept for either P3Dv4.x or P3Dv5.x that ended up being successful.



FYI: ADE did eventually implement a way to create sloped RWYs for P3Dv5, but IIRC, did not specifically address 'sloped' RWY AI Traffic:

https://www.fsdeveloper.com/forum/threads/sloped-runways.447342/




UPDATED: Ok, I refreshed my memory on a W.I.P. by Federico Sucari (aka "fs1") involving (2) DLLs for AI Traffic on sloped RWYs in P3Dv4.

https://www.avsim.com/forums/topic/...unways-in-p3d/?do=findComment&comment=4189808

https://www.avsim.com/forums/topic/571184-release-version-ais-now-following-sloped-runways-in-p3d/

https://www.dropbox.com/scl/fi/evklek6u9llq02b6bpf6o/AI.zip?rlkey=vhhhlql76ezhim33o9tt26x4c&e=1&dl=0


As I read further into the latter of the (2) threads linked above, AFAIK the reason these DLLs work is that they reference the actual terrain mesh / sloped flatten CVX TIN mesh ground surface Altitude- or FS' "synthetic" ground surface of hardened platform (and 'manifold' ?) 3D object surfaces that can effectively be assigned an internal virtual Altitude attribute relative to MSL (...or was it AGL ? ).

Also, IIUC, Lorby-SI had a module for P3Dv4 and 5 that may implement AI Traffic on sloped RWYs, although the author was not yet aware of the reason why such traffic was vanishing along its ground track at airports (possibly the need to have Parking Spaces at the assigned 'virtual' Altitudes of 3D modeled platforms ?).

https://www.avsim.com/forums/topic/575249-live-traffic-and-sloped-runways-p3dv5/

https://www.avsim.com/forums/topic/...runways-p3dv5/?do=findComment&comment=4236421


CAVEAT: One must use Parking Spaces at assigned Altitudes of 3D model 'virtual' ground platforms at airports so default A.I. Traffic works.


IIRC, implementation of "synthetic" terrain "ground" tiles was implicit within FS since at least FS5, but AFAIK, no one but Maurizio Gavioli's Vista Mare Software "ViMa*" modules in Lago, FSAddon, and Aerosoft addon packages made use of this option until FS2002 et seq..

At that time, IIUC, all other addon scenery packages that 'appeared' to use AI Traffic on sloped ground surfaces (ex: Aerosoft FS9 Madera, St Barthelemy) were 3D models of ground vehicles with animation following SCASM / ASM-based 'tracks', or MDL-based 'tracks' made in FS SDK compatible, animation capable applications such as 3DSMAX ...but not "true" AI Traffic SimObjects.

GaryGB