Sorry for the slow reply. We're madly working on getting Xj3D M6 out the
door and have been ignoring all emails.

Desiree Hilbring wrote:

I am still fiddling with your roaming classes and I have some questions:

1.
In SplitMergeLandscape there is a static variable:

private static final int AXIS_TILE_COUNT = 7;

What does that mean, the number of tiles to use on an axis (which axis?)?
Both axes. It's just a number that is used to control the maximum number
of tiles that we'll manage at any one point in time. On machines where
you are constrained by CPU resources, you don't really want to be
attempting to tile the entire world - particularly if you are running
with really large datasets that cover hundreds or thousands of
kilometres. For my machine, a PIII 800, that gave a reasonable amount of
visible terrain while keeping the workload down to something reasonable
allowing CPU cycles of other activities.

The x and y step are both 50, which is in world coordinates, right?
Yes. Everything in the ROAM code assumes world coordinates. Placing the
terrain under a transform is going to cause problems.

I would assume that I get a very small terrain with bounds ranging from
0 to 250 in both sides. Including your Roam test code into my project, I
am encountering problems locating the objects in the virtual world.
Printing the bounds information of each Patch creates bounds like the
following:
from
Bounding box: Lower=-200.0 3500.0 -200.0 Upper=0.0 3550.0 0.0 (thats only
one patch)
Even though you have said the terrain data is only 5x5 data points, the
ROAM algorithm works in powers of two data points for the size of each
patch. By default, the patch size is 64x64 data points, which is way
larger than your heights. If you want a terrain that is only 250 units
square, then you need to set the step distance to be closer together and
interpolate the height requests. This makes the overall size of the
patch to be 250, but using 64 datapoints in each direction.

--
Justin Couch                         http://www.vlc.com.au/~justin/
Java Architect & Bit Twiddler              http://www.yumetech.com/
Author, Java 3D FAQ Maintainer                  http://www.j3d.org/
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                                              - Greg Bear, Slant
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