Annonce

Réduire
Aucune annonce.

About Global Scenery HD

Réduire
X
 
  • Filtre
  • Heure
  • Afficher
Tout nettoyer
nouveaux messages

  • X-Plane 10.x About Global Scenery HD

    Nous avons un sujet en français, voir ici http://www.x-plane.fr/thread49914.html

    We already have a subject in french, see link above.


    As Andras Fabian (Alpilotx) does not understand french, I created this subject here in the english speaking part of the french forum.

    Here the mail I received from him:

    Hi Daniel!

    Nice to hear back from you. And, well, I was not really following the
    conversation ... but at least tried to figure out, what might be in
    there (and I have seen, that obviously there were "questions").

    To start with, I would highly recommend everybody who can read English,
    to check out this interview which I did with xplane10s Blog in December:

    It covers quite a bit of the background details about the base scenery!
    ...

    There was also an important change between XP9 and XP10. In XP9, the
    triangle mesh of the terrain was a 3D mesh. Which means, the mesh nodes
    had Z (elevation) information too, and added vertex normals. With XP10,
    the triangle mesh is only saved in 2D. Like a flat triangle mesh! And in
    the DSF we have now the "original" elevation raster data saved too. So,
    what XP10 does is, that it takes the 2D triangle mesh - like a veil -
    and puts it over the elevation raster data, and lets it take that shape.
    For one, this saves a little space in th DSFs (as it compresses much
    better this way, and needs a bit less "redundant" information). AND
    there is some other "secret" (well, Ben blogged about this too): this
    information can be used later, to reallyrefine the triangle mesh itself
    (which is not possible until now): its called "hardware tessellation"! A
    technique to refine triangle structures at runtime (by braking them up
    in smaller triangles) on the 3D hardware. And of course, with that
    refined mesh, the landscape could more accurately mimic the raster data.
    And no, this is no real secret :-) Ben blogged about this here:
    For something like six or seven years, DSF has fundamentally been a vector scenery format, meaning it contains points, lines, and connections between lines that define how scenery looks.  With X-Plane 10 we’ll be adding raster data to DSF. One way we’ll use raster data inside DSFs is to store the raw elevation data for […]


    Then, something about the raw data. SRTM is not incorrect, but neither
    entirely correct :-) . Yes, we use it in many places BUT there are also
    other sources. For all the northern latitudes (above 60 degrees North,
    there is no SRTM data!), and for many places where available, we use the
    fantastic data from http://www.viewfinderpanoramas.org/ (the 90m
    resolution data)! Yes, in the Alps too (and in the Alps,
    www.viewfinderpanoramas.org would even have 30m res data). Its a really
    good source (I love it, as it is - even at the same 90m resolution -
    more accurate than SRTM ... I have a few examples in the Dolomites,
    where I can really see the difference)!

    BUT still, the resolution of the triangle mesh structure is the
    limiting factor! So, if the triangles are too big, then the high res
    raster elevation data does not help much (at least not until we have
    hardware tessellation - somewhere in the future, don't ask me when). And
    that is where my HD Mesh tries to improve. More and smaller triangles
    result in better representation of the raster elevation data.

    By the way, there is also another advantage of the HD Mesh. Not only
    elevation information is bound to the triangle mesh, but also landclass
    information. When the DSFs are created, our processing tool assigns a
    terrain type (indirectly - via library.txt - these are the TER files)
    toeach triangle! And our Landclass data has much higher resolution
    (around 100m in Europe and USA) than the triangle mesh of the default
    Global Scenery can depict. Here, again, smaller triangles help to have a
    more exact representation of landclass information too (AND this is a
    poitn, which can't be improved by hardware tessellation - it can#t
    assign new terrain types on the fly to the smaller triangles ... at
    least not in the next years).

    Finally, here is a low-level screenshot from the GUI of our scenery
    creator (called RenderFarm), which compares the default triangle mesh
    (as its is in the default Global Scenery) with the HD Mesh. I think,
    here, everybody can see the difference:


    I hope I could answer a few questions ... and maybe, if your time
    permits, you might pass this on in your forum (if someone is interested
    in it at all :-) )!

    Have a nice day,

    Andras
    Feel free to ask questions here,

    Daniel
    Intel I5 6500 3,2 Ghz, RAM 16 Go, GeForce GTX 960 2 Go, Linux Ubuntu 18.04
    Portable Asus Intel i5 2,8 Ghz, RAM 8 Go, GeForce 840M, Windows 8.1 64bits
    #AMD II X2 245 2,9 Ghz, RAM 8 Go, GeForce GTX 650 1 Go, Linux Ubuntu 14.04
    #AMD 64x2 5200 2,6 Ghz, RAM 4 Go, GeForce 9600 GT 512 Mo, Linux Ubuntu 10.04
    #MacBook Pro 15" 2,4 Ghz, RAM 4 Go, GeForce GT 330 M 256 Mo, Mac OS 10.6

  • #2
    My own test at a place I know very well.



    Default Global Scenery



    Mesh HD version



    Mesh HD version
    To give more details I added this modified image.
    I know this place because I am working here for the last 20 years (see I work here). In the background you can see Pontoise Cormeilles LFPT airfield.
    Just below the airfield there is a park. It is the park of the castle of Grouchy. With more triangles, the shape of the park is really better than in the default scenery.
    On the right side the valley of the river Viosne. The river is located between the road and the rail. Now with mesh HD we can see more trees on the left side of the road and also houses along the road.
    I didn't put a red arrow there but on the left side of highway A15 now I can see fields instead of the texture underlying cities, as it should be.

    The real place is here : http://maps.google.fr/maps?q=Osny+ce...rance&t=h&z=14

    Daniel
    Dernière modification par Daniel_L, 21 mars 2012, 20h13.
    Intel I5 6500 3,2 Ghz, RAM 16 Go, GeForce GTX 960 2 Go, Linux Ubuntu 18.04
    Portable Asus Intel i5 2,8 Ghz, RAM 8 Go, GeForce 840M, Windows 8.1 64bits
    #AMD II X2 245 2,9 Ghz, RAM 8 Go, GeForce GTX 650 1 Go, Linux Ubuntu 14.04
    #AMD 64x2 5200 2,6 Ghz, RAM 4 Go, GeForce 9600 GT 512 Mo, Linux Ubuntu 10.04
    #MacBook Pro 15" 2,4 Ghz, RAM 4 Go, GeForce GT 330 M 256 Mo, Mac OS 10.6

    Commentaire

    Chargement...
    X