[Papervision3D] Terrain Demo with USGS SDTS DEM data

Wed Apr 25 15:52:30 EDT 2007

You're entirely right. I didn't know the SRTMD and the precision at 90m 
it offers is really surprising and...  really cool :)

Cedric
-----------------------------------------------------

Simon Hewitt a écrit :
> By the looks of it (please correct me if i'm wrong....) that data has a 
> maximum resolution of 2 arc minutes, which is about 2 miles/3 km. This 
> would be ok for low zoom levels (where my tiles are about 20 miles 
> wide), but I ideally need a much higher resolution in order to create 
> more detailed meshes. The Shuttle Radar Topography Mission Data 
> (http://www2.jpl.nasa.gov/srtm/) is much higher resolution (1 arc-second 
> [30m] in the US, and 3 arc-seconds [90m] in most of the rest of the 
> world, though there are some unsurveyed areas). The data i'm using at 
> the moment is very high resolution [2m] and accuracy, but i'm using it 
> under an academic licence and it is not freely available, plus it only 
> covers the UK. I intend to use the STRM data for the publically 
> available version of my app.
>
> Thanks,
> Simon
>
> Cédric JULES wrote:
>   
>> Hi.
>>
>> If it can help you, the Marine Geophysical Data Center (MGDC) let a free 
>> database for geophysical datas here:
>> http://www.ngdc.noaa.gov/mgg/gdas/gd_designagrid.html
>>
>> You can download custom-grid of datas of any size (put your 
>> coordinates), precision and many format (choice between ascii, binary, 
>> xyz, ...).
>>
>> To preview your downloaded files (to make sure it's what you need) just 
>> use the free software GEODAS here:
>> http://www.ngdc.noaa.gov/mgg/geodas/geodas.html
>>
>> I used this database and this software for a game some times ago, and it 
>> works very well.
>>
>> Enjoy.
>> Cedric Jules
>>
>> ------------------------------------------------------------------
>> Simon Hewitt a écrit :
>>   
>>     
>>> I'm doing something a bit like this... Basically implementing a 3D version of google maps.
>>>
>>> I am currently dividing the world up using the google maps tile coordinate system (a mercator with 
>>> different zoom levels) and generating a mesh for each of the tiles, then texturing them using satellite
>>> imagery. The triangle count is a bit of an issue, and as such i implemented a mesh simplification algorithm
>>> (see Surface Simplification Using Quadric Error Metrics by Garland and Heckbert, if you're interested) 
>>> to reduce the number of triangles for each tile sized mesh. The algorithm is quite complex and memory 
>>> intensive, so i wrote it in C++ and have pre-generated meshes with multiple triangle counts (between 20 and 60)
>>> for each of the tiles and store them in Collada format. I thought about using a view dependant simplification 
>>> algorithm, but added to the software 3D rendering, i think this will make things a bit too CPU intensive... 
>>> Maybe when i've finished doing it my way, i'll look into it.
>>>
>>> Currently i load the elevation tiles off my hard drive, but my eventual plan is to have an http tile server 
>>> to serve the required tiles to Flash/Papervision, probably just using apache and a perl script. I then load 
>>> elevation and image tiles into the Flex2/PV3D application in a google-maps style, prioritizing the images 
>>> and elevation tiles in the centre of the view, then moving out. 
>>> CPU usage is still pretty high, but performace is acceptable on my 1.5GHz laptop, and it flies by on my
>>> 3.4GHz desktop. Ideally, i'll make it configurable, so you can load 
>>>
>>> At the moment i'm using UK Ordnance Survey elevation data on an acedemic licence, so i'm not allowed to 
>>> make anything available on the internet. However, I shall adapt my mesh building algorithms to use the 
>>> SRTM data in a week or two, so it will be available to all. I'm also using google maps satellite images 
>>> straight off their servers, which is a bit naughty, but i have written it so you can plug in any URL to
>>> get the images from.
>>>
>>> There are still a few loading and memory related bugs to work out, but I should have a decent demo soon.
>>> for now, here's a screenshot:
>>> http://www.sjhewitt.co.uk/papervision/screenshot.jpg
>>>
>>> Cheers,
>>> Simon
>>>
>>>     http://www.overset.com/2007/04/24/papervision3d-terrain-map-v02-with-satellite-image-texture/
>>>
>>>     This is the same wireframe terrain map as below with satellite image
>>>     as the texture and a little bit higher triangle-count. We'll work on
>>>     the 100%CPU that you might see...
>>>
>>>     The more I think about this - the easier I'm thinking it would be to
>>>     write a flash remoting gateway wrapper to download WMS data from
>>>     USGS and other "open" WMS sources for DEM and Satellite imagery
>>>     (among many other layering options, i.e. DRP, DPLC (land cover),
>>>     LifeMapper (bear population), random etc. GIS layers) for instant
>>>     viewing through papervision3D on the fly. Essentially - a minimal
>>>     google earth (the application everyone and their sister has on their
>>>     desktop) all through flash with the help of papervision3D.
>>>
>>>     Thoughts?
>>>
>>>     --
>>>     Jim Palmer ! Mammoth Web Operations
>>>
>>>      >/ -----Original Message-----/
>>>      >/ From: Papervision3D-bounces at osflash.org
>>>     <http://osflash.org/mailman/listinfo/papervision3d_osflash.org>/
>>>     //>/ [mailto:Papervision3D-bounces at osflash.org
>>>     <http://osflash.org/mailman/listinfo/papervision3d_osflash.org>]On
>>>     Behalf Of Palmer, Jim/
>>>      >/ Sent: Saturday, April 21, 2007 4:54 PM/
>>>      >/ To: Papervision3D at osflash.org
>>>     <http://osflash.org/mailman/listinfo/papervision3d_osflash.org>/
>>>     //>/ Subject: [Papervision3D] Terrain Demo with USGS SDTS DEM data/
>>>      >/ /
>>>      >/ /
>>>      >/ /
>>>      >/ http://www.overset.com/2007/04/21/papervision3d-terrain-map-of/
>>>     //>/ -mammoth-mountain-ski-area//
>>>      >/ /
>>>      >/ Just put together a simple proof-of-concept by taking the /
>>>      >/ USGS D.E.M. (Digital Elevation Model) data in SDTS format, /
>>>      >/ converted it to a huge array of Vertex3D objects and did a /
>>>      >/ ghetto-fab "triangulation" of the vertices for the Face3D objects./
>>>      >/ /
>>>      >/ I'd honestly LOVE to put together a SDTS DEM to papervision3d /
>>>      >/ Mesh3D conversion utility to literally load SDTS data on the /
>>>      >/ fly, but that will not happen too soon =[/
>>>      >/ /
>>>      >/ It appears to be 3080 Vertex3D objects and 5933 Face3D /
>>>      >/ objects with my ghetto-triangulation./
>>>      >/ /
>>>      >/ The "wireframe" texture with doubleSided=false seems to do /
>>>      >/ alright in terms of performance and falls within the 15sec /
>>>      >/ script execution limitation. /
>>>      >/ We'll see how this does with a texture applied, if I can even /
>>>      >/ accomplish this easily./
>>>      >/ /
>>>      >/ ..comments?/
>>>      >/ /
>>>      >/ --/
>>>      >/ Jim Palmer ! Mammoth Web Operations/
>>>      >/ /
>>>      >/ _______________________________________________/
>>>      >/ Papervision3D mailing list/
>>>      >/ Papervision3D at osflash.org
>>>     <http://osflash.org/mailman/listinfo/papervision3d_osflash.org>/
>>>     //>/ http://osflash.org/mailman/listinfo/papervision3d_osflash.org/
>>>     //>/ /
>>>
>>>
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