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 think).

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.

Jeff

Vassilis Chryssos wrote:

Hello all.

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?

My map resembles this one: http://www.atsdr.cdc.gov/HAC/PHA/alaskap/apc-f3.gif

And the result I am trying to achieve resembles this one: http://img.photobucket.com/albums/v291/americanfishguy/Buildings/Australia.png

The blender effect I want resembles this one: http://gchen.sdf-eu.org/Chengine/Images/Screenshots/HeightMap.jpg

Maybe a big ask, Hessain *might* do part of it for you

http://freshmeat.net/projects/hessiangtk/?branch_id=61861&release_id=213079

Owen

Vassilis Chryssos wrote:

Hello all.

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?

I have not tried anything like this. For the US the National Elevation Database provides excellent DEM at 1/3 arc sec granularity.

Here is a ref that describes the kind of process you are interested in: http://www.terrainmap.com/rm19.html

I would recommend getting the SRTM DEM data for your area of interest. It is provided in 1 degree squares. There are various programs such as MicroDEM which can convert the DEM data into raster images, and also generate 3d views with selectable height exaggeration.

I believe this link is for the current processed SRTM version 2 which I think is the latest (or maybe final) version.

ftp://e0srp01u.ecs.nasa.gov/srtm/version2/

scott s. .