Importing terrains + Adding extra terrain

[ksraghavendra]

Hi,
I am a Terragen newbie, I have some elevation data as LAS(lidar) and I have converted it to Terragen format using Global Mapper. It is a small area and I need to add some surrounding terrain. I tried using Power Fractal but when I am doing so the elevations in the actual terrain I imported are also getting modified/increased. How do I solve this problem?
Also the surrounding fake terrain that I add has to match with the edges of the actual terrain I have imported. I am getting a step after my terrain now.
Thanks in advance,
Regards,
Raghav

[Henry Blewer]

It's not easy, but it is not too hard. I have not done anything using real data, so this is a guess. The Power Fractal needs to be first in the Terrain tab's input. The Heightfield loaded in next. This should make the heightfield terrain sit on the Power fractal terrain.

Next you need to select the heightfield and choose the operator from the operators menu ( Heightfield Adjust Vertical) and ajust the Add Height so it fits better into the Power Fractal's terrain. Reselect the Heightfield shader and near the bottom is Border Blending. This controls how much the heightfield merges into the power fractal.

Last, this is the tricky part, you need to change the power fractal terrain settings to approximate the data in the heightfield. This is done by adjusting the noise type, the displacement information, and the scales.

[Oshyan]

Making the edges match exactly will be difficult, unfortunately. There is some sophisticated mask trickery you can do, described here:
http://forums.planetside.co.uk/index.php?topic=2036.0

For a more basic approach, you would use Flatten Surface First in the Displacement tab, then adjust border blending, and then all you can do is tweak your Power Fractal to match. You might consider instead using a 3rd party heightfield tool to create a larger-scale but lower-resolution surrounding heightfield that can more exactly match the bit of terrain you have.

- Oshyan

[Henry Blewer]

Wow, BigBen really did his homework! Oshyan, thanks for pointing to his thread. I have not read back that far in the forum. My way is simpler, but not very good for animating or for quite a few POV's.

[ksraghavendra]

Hey thanks guys for your inputs, I tried njeneb's method(i couldn't digest the methodology proposed in BigBen's link completely), it almost worked out but I have a typical case, the difference in terrain within my area of interest is almost 200 meters and I am working on a Hydro power project site and I am losing some valuable part of my site with border blending.
I have a small doubt here, when I overlay a terrain over another how does Terragen treat them? Does it add up the elevations of both the terrains or displays the higher of the two terrains?
Also in order to avoid using a power fractal, I downloaded SRTM DEM and placed my site over it. So as a result I will be having good height accuracy in my area of interest and lesser resolution in the rest of the area. But the problem is when I am feeding lat/long values of my SRTM DEM and my Site terrain, these both seem to go below the terrain(some -5000m below ground level). I have tried all sorts of ways to bring it back to normal level but failed to do so. Pls help me out.

[ksraghavendra]

As the site is a Hydro Power proj site, I also need to add some objects such as a Dam and its related units(powerhouse, pipelines, towers, etc). Do we have any free libraries containing regularly used objects? Can we import from SketchUp which has a good free collection of such objects?

[Kadri]

As the site is a Hydro Power proj site, I also need to add some objects such as a Dam and its related units(powerhouse, pipelines, towers, etc). Do we have any free libraries containing regularly used objects? Can we import from SketchUp which has a good free collection of such objects?

You can import  LWo . OBJ and TGO objects . TGO is a Terragen format . From the others the best to use is OBJ .
If you have trouble with OBJ , here in the forum are many topics for help about this.
In most topics you will see that the free Poseray program is heavily suggested for OBJ importing-preparation .

Edit : You have to convert other formats to the ones above obviously . For objects here , look at the file sharing section in the forum .
        http://www.terragen.org/  and http://www.nwdanet.com/ have objects too. Of course on the web there are many of free objects websites .
        http://www.hongkiat.com/blog/60-excellent-free-3d-model-websites/

Kadri.