<s>
Daylon	B-Application
Leveller	I-Application
is	O
a	O
terrain/heightfield	O
modeling	O
program	O
made	O
by	O
Daylon	O
Graphics	O
Ltd	O
.	O
of	O
British	O
Columbia	O
,	O
Canada	O
.	O
</s>
<s>
Leveller	O
began	O
as	O
a	O
fork	O
of	O
Gardener	O
's	O
earlier	O
NavCam	O
utility	O
for	O
the	O
POV-Ray	B-Application
raytracer	O
.	O
</s>
<s>
It	O
uses	O
several	O
third-party	O
libraries	O
,	O
notably	O
GDAL	B-Language
which	O
provides	O
georeferencing	O
and	O
additional	O
file	O
format	O
support	O
,	O
and	O
Lua	B-Language
which	O
lets	O
plug-ins	O
and	O
macros	O
be	O
easily	O
scripted	O
.	O
</s>
<s>
Leveller	O
documents	O
appear	O
in	O
a	O
two-paned	O
window	O
showing	O
a	O
nadir	O
(	O
top-down	O
)	O
view	O
of	O
the	O
heightfield	B-Data_Structure
and	O
an	O
OpenGL-based	O
view	O
showing	O
the	O
heightfield	B-Data_Structure
(	O
and	O
related	O
elements	O
)	O
in	O
3D	O
.	O
</s>
<s>
Modeling	O
is	O
based	O
on	O
a	O
paint-program	O
metaphor	O
similar	O
to	O
Adobe	B-Operating_System
Photoshop	I-Operating_System
,	O
with	O
brushes	O
,	O
selection	O
tools	O
,	O
etc	O
.	O
</s>
<s>
Heightfields	B-Data_Structure
can	O
be	O
planar	O
(	O
flat	O
)	O
or	O
distorted	O
using	O
UV	O
displacement	O
mapping	O
onto	O
spheres	O
,	O
sphere	O
sections	O
,	O
cones	O
,	O
cylinders	O
,	O
etc	O
.	O
</s>
<s>
situate	O
edits	O
and	O
generate	O
heightfield	B-Data_Structure
selection	O
masks	O
and	O
formations	O
.	O
</s>
<s>
Leveller	O
can	O
export	O
scenes	O
to	O
POV-Ray	B-Application
,	O
RenderMan	B-Application
,	O
and	O
VRML	B-Application
.	O
</s>
<s>
Leveller	O
is	O
available	O
for	O
32-bit	O
and	O
64-bit	O
Microsoft	B-Application
Windows	I-Application
(	O
version	O
2.6	O
+	O
include	O
some	O
minor	O
compatibility	O
fixes	O
for	O
Vista	B-Application
and	O
for	O
Windows	B-Device
7	I-Device
)	O
.	O
</s>
