Hi Tracers!

My first serious attempt at an Afghan landscape (to those of you
familiar with the country, it's the lower Arghastan plain about 30 miles
south-east of Kandahar...)... after weeks of arduous manual pixeling
work on a scanned b/w 1:300.000 topographic map of the area, I finally
got together a preliminary 16bit heightfield of 198 by 500 pixels, each
pixel representing a square with sides of 25.4 meters. Of course, I also
wanted a realistic surface texture - and that's where many problems
begin.

Firstly, as I have the ambition of constructing a virtual (pre-war)
Afghanistan scenery as authentic as possible, I'm desperately looking
for detailed photographs showing soil types, terrain formations,
vegetation, examples of single grasses, weeds and other plants etc. of
southern Kandahar province, not to mention specific human influences on
the landscape such as agricultural usage patterns, irrigation systems,
roads and tracks, traditional village architecture and many more... and
also inhabitants of both sexes and all ages, as in the more distant
future, I will populate my scanned map quadrant (finally, the
heightfield will measure 1863 x 2205 pixels... 4 million pixels to be
placed by hand, ouch!) with actual Afghans...

Also, it became soon clear to me that simple image_maps can't be the way
to get a proper texture for my landscape, even with my current image_map
at a resolution 10 times higher than the heightfield, each pixel is
still 2.54 meters, way too large for such fine structures like
irrigation channels or narrow tracks between the fields (I attached a
small version of the image_map here). Because of the very different
finish properties of e. g. water and rock, I'll have to use texture
maps. And within these single textures contained in the map(s), I beginn
asking myself how to achieve special surface structures like chains of
shallow pools in the partially dry beds of temporary rivers (like the
Arghastan river which can be seen in the attached renderings),
alternating with still moist mud, cracked dry mud, accumulations of
pebbles or gravel, sand drifts etc. on a procedural basis. I even would
by ready to change to MegaPOV or PoV-Ray 3.5...

SEE YOU IN KHYBERSPACE!!!
(also: http://www.geocities.com/electricafghan/index-e.html)
Afghanistan Chronicle: http://www.ndh.net/home/bleimann/

Yadgar

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Attachments:
Download 'spinboldak0015.jpg' (28 KB) Download 'spinboldak0016.jpg' (49 KB) Download 'spinboldak0024.jpg' (25 KB) Download 'spinboldak0025.jpg' (12 KB) Download 'spin_boldak_texture_2001-12_demo.png' (50 KB)

Preview of image 'spinboldak0015.jpg'

Preview of image 'spinboldak0016.jpg'

Preview of image 'spinboldak0024.jpg'

Preview of image 'spinboldak0025.jpg'

Preview of image 'spin_boldak_texture_2001-12_demo.png'

Could be difficult but material_map might be the way to go.  Slope dependant
texturing (MegaPOV and v3.5 beta) is a possibility but not a plausibility to
get such precise things done.  For instance, the crop fields wouldn't adhere
to only a particular slope and should instead go where wanted so that would
necessitate being placed manually.  And without a lot of definition to
elevations the water channels might prove difficult too, your pictures look
very flat in those places and any downstream slope change would make that
impossible anyhow.
So I'll guess material map using your drawing as the guide would be the best
answer.  Just that you will need a lot of textures made for it.  Look it up
in the Scene help if you never used it before.
--
text{ttf"arial","bob h",.1,0pigment{rgb 9}translate<-1,-.2,3>}

"Yadgar" <j.b### [at] ndhnet> wrote in message
news:3C1D70ED.F71BCA01@ndh.net...
> Hi Tracers!
>
> My first serious attempt at an Afghan landscape (to those of you
> familiar with the country, it's the lower Arghastan plain about 30 miles
> south-east of Kandahar...)... after weeks of arduous manual pixeling
> work on a scanned b/w 1:300.000 topographic map of the area, I finally
> got together a preliminary 16bit heightfield of 198 by 500 pixels, each
> pixel representing a square with sides of 25.4 meters. Of course, I also
> wanted a realistic surface texture - and that's where many problems
> begin.
>
> Firstly, as I have the ambition of constructing a virtual (pre-war)
> Afghanistan scenery as authentic as possible, I'm desperately looking
> for detailed photographs showing soil types, terrain formations,
> vegetation, examples of single grasses, weeds and other plants etc. of
> southern Kandahar province, not to mention specific human influences on
> the landscape such as agricultural usage patterns, irrigation systems,
> roads and tracks, traditional village architecture and many more... and
> also inhabitants of both sexes and all ages, as in the more distant
> future, I will populate my scanned map quadrant (finally, the
> heightfield will measure 1863 x 2205 pixels... 4 million pixels to be
> placed by hand, ouch!) with actual Afghans...
>
> Also, it became soon clear to me that simple image_maps can't be the way
> to get a proper texture for my landscape, even with my current image_map
> at a resolution 10 times higher than the heightfield, each pixel is
> still 2.54 meters, way too large for such fine structures like
> irrigation channels or narrow tracks between the fields (I attached a
> small version of the image_map here). Because of the very different
> finish properties of e. g. water and rock, I'll have to use texture
> maps. And within these single textures contained in the map(s), I beginn
> asking myself how to achieve special surface structures like chains of
> shallow pools in the partially dry beds of temporary rivers (like the
> Arghastan river which can be seen in the attached renderings),
> alternating with still moist mud, cracked dry mud, accumulations of
> pebbles or gravel, sand drifts etc. on a procedural basis. I even would
> by ready to change to MegaPOV or PoV-Ray 3.5...
>
> SEE YOU IN KHYBERSPACE!!!
> (also: http://www.geocities.com/electricafghan/index-e.html)
> Afghanistan Chronicle: http://www.ndh.net/home/bleimann/
>
> Yadgar
>


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Post a reply to this message

On Sun, 16 Dec 2001, bob h wrote:

> Could be difficult but material_map might be the way to go.  Slope dependant
> texturing (MegaPOV and v3.5 beta) is a possibility but not a plausibility to
> get such precise things done.

If you're using MegaPOV or v3.5 beta you can use an image pattern with a
pigment_map or texture_map, which combines the capabilities of
material_map with the "average" pattern. It works like painting with POV
textures instead of colors (although the display in your paint program
will of course be the greyscale image.)

John Haiducek

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Yadgar wrote:
> 
> Hi Tracers!
> 
> My first serious attempt at an Afghan landscape (to those of you
> familiar with the country, it's the lower Arghastan plain about 30 miles
> south-east of Kandahar...)... after weeks of arduous manual pixeling
> work on a scanned b/w 1:300.000 topographic map of the area, I finally
> got together a preliminary 16bit heightfield of 198 by 500 pixels, each
> pixel representing a square with sides of 25.4 meters. Of course, I also
> wanted a realistic surface texture - and that's where many problems
> begin.
> 

The most common method is to use satellite or aerial photography and
classify them according to a set of surface types.  

Some info on this can be found for example in:

http://www.cs.utah.edu/vissim/papers/snowTerrain/

You can also try to conclude the information from the terrain geometry
like done in:

http://www.graphics.lcs.mit.edu/~boh/Projects/snowGenFinalWrite.html

for snow, but without further information this will be very inaccurate.  

Christoph

-- 
Christoph Hormann <chr### [at] gmxde>
IsoWood include, radiosity tutorial, TransSkin and other 
things on: http://www.schunter.etc.tu-bs.de/~chris/

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