On Sun, Nov 27, 2005 at 01:00:56PM +0200, Vassilis Chryssos wrote:
> This is what I'm trying to achieve: I have a topographical chart (curves
> that depict the height of a territory) which I want to use as a
> heightmap for blender. Blender uses gradient grayscale images to raise
> the pixels of a plane according to the "whiteness" of each pixel (i.e.
> the white pixel will be raised to the higher level, whereas black pixel
> will remain to the bottom. The in-between pixels will be raised
> according to their value of white).
> With this in mind someone must create a grayscale gradient image out of
> the topographical chart.
> Could someone suggest a smart way to apply grayscale gradient to the
> image according to the height specified by the curves?

Wow, um, yeah.  I know what you are wanting to do, I'm just not sure the
GIMP or even your source map are the right tools for the job.

For the GIMP to be able to do something like that automatically, it would
have to be able to distingush the isoclines from the river drainages, trail
markings, text, etc.  Then, once we know which are the isoclines, they would
have to be closed (several of them are not), and it would have to have some
way of telling which are heading up and which are heading down (which is
only hinted at in places with the elevation text).  Given that all this is
unsurmountable by automated means, we turn to hand driven.

Much the same way, you would need to remove everything that wasn't an
isocline, and make sure that all the isoclines were closed.  You could then
select by region with a 0 threshold and fill each isocline with the
appropriate color.  That would leave the isoclines themselves to deal with,
but when you were all done with the (very tedious process), you would have
something that looks like your australia map.

But, that won't get you to the blender map.  You would end up with a
terraced effect that would look very strange.  You could use a blur to get
rid of some of the terracing, but that isn't really whay you want (I don't

Might I suggest finding out the latitudes and longitudes of the map you want
to do, and downloading the DEM data for the region?  The data is all
available online (legally) for free if you look hard enough, and you should
be able to find a high enough resolution for your needs.  I personally have
a copy of the DEM data for the Earth at a very low resolution (much, I'm
sure, than would work for your map).  And, I can send it to you so you can
get an idea of what you would be looking at if you like.


Computer Science is as much about computers as astronomy is about telescopes
        -- Edsger Wybe Dijkstra (1930-2002)

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