Creating a real site model

[DanielHruby]

I am an architect interested in creating a site model of Lake Tahoe.  The property in question is modeled in ArchiCAD as a mesh.  I can export this mesh to Modo as a .3ds or .obj file and create a better quad mesh by draping a flat mesh over the rather chunky triangulated archicad site mesh and then smoothing it out with Modo tools.  From this, I can render a top view of the site as a Depth Channel, which I am hoping could be used as a height field generator.

The second part of the exercise would be to export the entire lake area from Google earth into Sketchup and follow the same process to create a less accurate model to merge with the accurate site model.  The end result would be my starting point for generating a mesh in Terragen2. 

As I have only recently bought the software, I want to ask if this seems like a process that could work in Terragen or if there is a better way to get a model to render that looks like a reasonable lake with an accurate building site.

Thank you.

[rcallicotte]

I have never tried this, so I won't be a lot of technical help.  But, since files like DEMs and similar file formats are supported in TG2, you should be able to find someone who has a heightfield map somewhere online in the exact spot you need (Lake Tahoe, right?) with high-quality settings.  Once you imported this into TG2, you could then export this mesh as an LWO format to be used in your other 3D application. 

I realize this process as described contains some holes, where I haven't explained much.  It's possible this isn't the information you wanted.

[DanielHruby]

No, this is good info.  I have no idea where to look for height field maps that are reasonably accurate.  Can anyone point me in the right direction for such a map of Lake Tahoe?  I will start searching myself now.

Thank you.

[Tangled-Universe]

You might try to find maps here:

http://seamless.usgs.gov/index.php

It's probably not that well detailed, but you can always add detail in TG2 easily and then export the more detailed mesh to LWO and then import it into your 3D-package of choice, like Calico said.

I have no experience in this type of work at all, but my approach would be something like this:

1) create scene of lake tahoe with desired elements and point of view (POV). Render this image in your desired resolution.
2) export the terrain as a mesh with the LWO-exporter (like Calico said)
3) export camera-settings from TG2
4) import terrain mesh and camera and match with scene created in TG2
5) place archiCAD-mesh into scene and render the mesh + shadows etc. in separate passes
6) merge and adjust elements in photoshop

This is in a nutshell what I would do and I probably missed some (important) things but to my idea this should be basically it.
I can be of good help regarding point 1, but from there my expertise stops

Martin

[RArcher]

See if this works for you.  It is a .ter file of the Lake Tahoe area at 1/3 arc second (10m) resolution.  I downloaded the data from the previously given link seamless.usgs.gov, then merged and exported it into a .ter file using globalmapper.  Theoretically, when the final version is released you will be able to directly load 16bit geotiff's but not quite yet.

http://www.archer-designs.com/temp/lake-tahoe/lake-tahoe-2049.zip

[DanielHruby]

Thank you RArcher!  I appreciate the effort you put into providing thi to me.  I will check it out and see if I can do anything with it. 

[JimB]

I've done a similar thing a number of times, and it's a sound approach overall. I always found adding a teeny weeny bit of erosion using World Machine makes the terrain look a whole lot better, and makes up for loss of detail usually inherrent in the original DEM/heightfield. One thing you should watch out for is the height map derived from the mesh will possibly have the mesh's triangles visible in the resulting height map. Some smoothing or Subdivision may be required.

Useful apps:
http://www.world-machine.com/
http://koti.mbnet.fi/pkl/tg/TerraConv.htm
http://www.visualizationsoftware.com/3dem.html
http://www.planetside.co.uk/terragen/resources.shtml

[gregsandor]

One suggestion I'll add here is that when you select the area at the USGS seamless server, in the Modify Data Request page tick the box for the .tiff orthoimagery.  In addition to your .dem you'll also have a georeferenced image that exactly matches your terain.  The DRG (topo map) is also useful for locating stuff on the terrain.

[DanielHruby]

See if this works for you.  It is a .ter file of the Lake Tahoe area at 1/3 arc second (10m) resolution.  I downloaded the data from the previously given link seamless.usgs.gov, then merged and exported it into a .ter file using globalmapper.  Theoretically, when the final version is released you will be able to directly load 16bit geotiff's but not quite yet.

http://www.archer-designs.com/temp/lake-tahoe/lake-tahoe-2049.zip

After some time, i am revisiting the import of real GeoData into TG2.  This time, i need to try a piece of Hawaii.  I tried to use the USGS seamless server.  I was not sure what settings to use to download.  So I used these settings.  I am not sure what the proper settings need to be here in order to get a .DEM:





This is what I got downloaded to me.  But I dont know what to use here with TG2.  I dont see a .DEM







Can anyone help me get a grasp on how to get as accurate a model as possible into TG2 via this approach? RArcher graciously went as far as to provide me the Tahoe model, but I didn't learn the process for getting the right data and doing the import.

There is also mention of using the server for.tiff maps.  I can't seem to figure out a way to get this to show or download either.

Thank you in advance.

[Matt]

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[Matt]

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[mhall]

Wow - what a succinct tutorial.

Someone needs to put that in the wiki.

Thanks Matt!

[DanielHruby]

Thank you!  I will give it a try again.  I assume the type of map downloaded is the best resolution?

EDIT:

I managed to get the file downloaded.  But upon inspection of the 48 MB .TIFF in Photoshop it appears that the land area is almost entirely white (or flat) with no apparent height gradaition except right at the shoreline there can be some grays.  There should be a gradual  up slope up from the beach.  Any ideas?  Could there be a range to define for the height field?

[Matt]

The values in the geotiff are in metres. They won't look correct when viewed in Photoshop, because Photoshop will probably interpret an elevation of 1 metre as being full white, and probably also anything greater than 1 metre. Just load it in Terragen and you should see correct elevations.

BTW, for my tutorial above I downloaded a Geotiff from exactly the same location as your screenshot, and the volcanic cone in your screenshot was clearly visible in Terragen once I moved the camera close to it.

Matt

[DanielHruby]

Thanks again Matt.  I have had a model rendering all day so I could not load it yet.  That is why I thought I might see a grayscale version of the terrain.  I will try to complete your steps before crying for help again.