Terragen FAQ
Problem Solving - Known Bugs/Limitations
Last updated May 25, 1999.
This FAQ is mostly aimed at questions about how to solve
problems in Terragen. For questions about the background and
future of Terragen, see Hugo's
FAQ, written by Hugo Elias.
Problem Solving
If you are having problems with Terragen, check this list
first before emailing Matt or the Terragen Mailing List with the
problem.
- The sky doesn't reach all the way to the
landscape, leaving a black area.
In the Clouds dialog box, increase the Sky Size
and try again.
- One or more of the Surface Map Distribution
Settings don't do anything.
Uncheck the "Effective" checkboxes and
recheck them.
- When I run script files, they produce errors.
Make sure that the decimal separator is a period
(.) and not a comma (,). This is most likely to happen on
European versions of Windows.
- When I render images, the colours do not blend
together and instead are "banded".
Make sure that your display is configured for
TrueColor (24/32bit) and not HiColor (16bit) or 256
Colour. You can change this through Display Properties (in
Control Panel)
- Some parts of the image don't seem to be rendered
properly, missing out parts of the terrain.
Make sure that the camera isn't under the
landscape, or underwater! This can happen if you enter
the z-coordinate of the camera manually, or sometimes by
other factors. Setting the "Fixed Height above
Surface" checkbox and entering an appropriate value
(default is 1) can fix this.
If this is not the problem, then try turning off Backface
Culling (found in Render Settings on the Render Control
dialog).
- No settings are available for Surface Map.
You have to click on either "Landscape" or one
of the two sub-items before options become available.
- The heightfield map on the Render Control dialog
looks wrong.
This is a known problem and is being worked on - This
will not cause any problems when rendering. On some
systems, this map will not be shown at all. This will not
affect rendering in any way.
- When I try to render water, it seems totally flat
some distance from the camera.
This is a known problem - Increase the wave size to
reduce this happening.
- How can I reduce rendering times?
The first question to ask is, "Do I really need all
the accuracy settings so high?". Often, image
quality is barely altered by reducing Atmospheric
Accuracy (in the Render Dialog),
and unless 3D Clouds are selected, Cloud Accuracy
settings above middle are rarely needed.
- How can I improve the quality of my finished
pictures?
Terragen does not currently support antialiasing, often
resulting in "sharp" edges between land and sky.
You can work around this by performing your own
antialiasing - by rendering images larger than required
and then "resampling" them to the desired
resolution. Most good image processing programs support
resampling, and I recommend the particularly good Paint Shop Pro. In
addition, Daniel
Parnham's program Bitty is good for antialiasing
especially for large numbers of images (e.g. for an
animation). For more information about post-processing,
see the Post Processing guide.
Turning on 3D Clouds can also make a big difference to
the sky, as long as you increase Cloud Shade Accuracy as
well.
You could also play with the Surface Map system to create
more complex surface maps.
- Why do low zoom values look so bad?
Real-world cameras use a "spherical" lens,
while Terragen does not (yet?) imitate the effect of one.
Known bugs/limitations
- An error sometimes occurs when redrawing the surface map
system on the large preview window on the Terrain Dialog.
- You can not save Surface Map files as yet. There are some
sample surface map files that can be loaded but these are
only two-colour maps and not recursive maps. Terragen
version 0.7 will have a new surface map system which can
save surface map files.
- Very large image sizes can cause the program to crash.
1280*960 seems to be the highest "standard"
screen resolution that is safe. It seems that at present,
Terragen does not support vertical sizes of over
1000 - therefore 2000*1000 would work, 5000*1000 would
work, etc.
- With some graphics cards, the small terrain map in the
Render Dialog and the Lighting map may not display
correctly. This will not affect other operations in the
program. These problems may be cured by upgrading your
video drivers.
- Terragen is not multithreaded. There is no
advantage in using a multiprocessor system unless you
want to have two copies running or other programs not
slowed down. This will probably change in a later release.