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Thread: DEM Terrain...

  1. #1
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    DEM Terrain...

    Hi,
    Whilst watching the Terrain generator videos I wondered if there was a way that we could use and of the free DEM (Digital Elevation Model) files that are available. Then in the last radio show it was briefly mentioned about modelling Everest using a DEM! So I thought I'd look into how easy it would be, and wrote a DEM file importer/decoder as a replacement for the TerrainGenerator.cs file (which hasn't yet been presented). It needs some work, and it takes quite a long time to produce the output, but here are a couple of DEM files that I have loaded into the presented DemoFramework terrain.
    The terrain is split into 100x100 sized patches that together build up the terrain. The code needs quite a bit of tidying up, hopeful I'll post it sometime soon!

    Regards,

    Phd.

    This is a small test DEM file (~1M) of an area of Honolulu:


    This is a much larger DEM file (~170Mb) of Lake Tahoe:
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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    Last edited by phd; 02-28-2011 at 12:50 PM.

  2. #2
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    Nice work! In order to use DEM for the MMO i think we would need to invest some time into streaming. I'm not a DEM expert but I recall the data storage requirements being pretty extensive compared to something like heigtmap. Anyway, this is really cool, keep up the great work and keep us posted if you continue progress here

  3. #3
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    Wow very nice! I'm glad to see more new terrain stuff. I hope we don't get all caught up in realtime sculpting. Seems things have taken a pause otherwise.

  4. #4
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    Quote Originally Posted by tomo View Post
    Seems things have taken a pause otherwise.
    How so?
    .

  5. #5
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    Just looking forward to seeing a follow up VTM on: Lee's Terrain R&D, Pt. x - Stitching / Seaming patches

    As we've been talking about Dynamic Terrain Gen using perlin noise. and even demo'd LOD, now seeing screen shots of Realtime Sculpting.

    I think all that stuff is great but what happened to stitching?

  6. #6
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    Good work on getting DEMs imported into the terrain framework. Its looking really sharp.

    The second image (Lake Tahoe) if I'm looking at what I think I am that is the compilation of the 18 7.5 minutes quadrangles 10m DEMs that make up the entire Lake Tahoe basin. For those who may be wondering a 7.5 minute quadrangle map covers approximately 64sq miles so 18 of them make up about 1,152 sq miles.

    As jjguzzardo pointed out DEMs are very expensive memory wise just the Lake Tahoe basin is almost 175 megs in size. It yields very nice looking results though and if you only need data for small zones or levels it isn't a bad way to go. In our case though with one of the goals being larger worlds the memory storage requirements was one of the reasons it was ruled out. The other reason is that once you start to scale the data to spread across many patches you start to lose fidelity and the landscape starts to look stair stepped or like it has many tiered plateaus which was also undesirable.

    The solution that I came up with which will be shown in the next set of R&D videos that will be out very shortly. Jason and I stayed up all last night to record and we'll be finishing them up this afternoon so they'll probably be out in the next day or so. Basically the solution uses a height map in a way that allows you to scale the terrain to any size you want with out losing fidelity. Granted the results don't look as realistic as those from a DEM but they look good enough for an MMO.


    The above image represents about 2,100sq miles and uses only 532KB of storage as apposed to the nearly 175MB to hold the DEM data that covers about a 1,000 less sq miles.

    Now please don't take me wrong I'm not condemning DEMs, they are great, just not so much so for our purposes. Though looking at the excellent results you got I may want to play with using one as the source data that drives the procedural generator in the R&D demo.


    I have to say I'm a bit confused about this one tomo. Care to elaborate?

    Quote Originally Posted by tomo View Post
    Wow very nice! I'm glad to see more new terrain stuff. I hope we don't get all caught up in realtime sculpting. Seems things have taken a pause otherwise.
    We are working on R&D at the moment which will eventually lead into tool development. Since the RACE (Realtime Artist Collaborative Environment) system is something we are very much interest in seeing as a tool and possibly as a game mechanic for the MMO how is being caught up in its development and testing a bad thing?

    If you think "things have taken a pause" did you miss the 7 or 8 hours of class meetings this week? Where we took an in depth look at the Elythians history via Zak's awesome narrative and where we had several equally interesting discussions on possible game play mechanics.

    It can be difficult to understand exactly how much work goes into our projects unless you are directly involved. For instance the 70 plus hours of free Unity content. One might think oh its only 70hrs that's not so bad. What they don't see is the 1,000 to 1,500 hours of research, meetings, building, testing, refining, travel(for me), recording, editing, encoding, publishing, and ongoing support that went into just that one product. And the free Unity content can't even begin to compare to the scale of the MMO project. Believe me nothing is on pause if anything this project is being pushed harder and faster than anything we've done before. Remember the MMO class was estimated to only bring out about 2 hours of content a week. We are already sitting at nearly 20hrs of content with another 7 or 8 hours about to come out today or tomorrow and there is still another week left in the 1st month of the class.

    If you still think we aren't moving fast enough I may invite you to ride shotgun on one of my marathon 20hr R&D sessions ask fatgav what they're like he's joined me for a few of them over the last couple weeks.

  7. #7
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    Quote Originally Posted by tomo View Post
    Just looking forward to seeing a follow up VTM on: Lee's Terrain R&D, Pt. x - Stitching / Seaming patches

    As we've been talking about Dynamic Terrain Gen using perlin noise. and even demo'd LOD, now seeing screen shots of Realtime Sculpting.

    I think all that stuff is great but what happened to stitching?
    You think you can sculpt across patches without stitching having already been solved? Did you see any tears in the screen shots? As to dynamic LOD that has went away since Unity can't handle it fast enough in real time. It actually runs faster using full detail patches than it did with the LOD system in place. Which is why we are doing these R&D's in the first place to see what works and what doesn't. Terrain LOD just isn't viable so I found a work around.

  8. #8
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    Quote Originally Posted by tomo View Post
    Just looking forward to seeing a follow up VTM on: Lee's Terrain R&D, Pt. x - Stitching / Seaming patches

    As we've been talking about Dynamic Terrain Gen using perlin noise. and even demo'd LOD, now seeing screen shots of Realtime Sculpting.

    I think all that stuff is great but what happened to stitching?
    Hey Tomo!

    Just a quick note, after last night's class, Lee and I recorded until 5 am this morning! My left ear is still killing me for having the mic on for nearly 10 hours!

    I'm encoding videos now... they'll start appearing very soon.

    Cheers!

    Buzz

  9. #9
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    You rock dude !!! Did I ever tell you that? Cheers !!!

  10. #10
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    Quote Originally Posted by chronos78 View Post
    Basically the solution uses a height map in a way that allows you to scale the terrain to any size you want with out losing fidelity. Granted the results don't look as realistic as those from a DEM but they look good enough for an MMO.
    I don't know anything about DEM's except for what was posted in the thread so this might be a stupid question but is it possible to use the DEM to generate height maps that can be used in the current terrain system?

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