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Alvary
05-17-2010, 07:31 PM
Hey there!
Last time I was mapping (using gimp) I was having a little trouble getting my mountains to lay out well on my maps. This got so frustrating that I put my maps aside for a while. Well, last night I had an idea. As I was testing it out I took some screen shots. I apologize for the terrible quality...my internet is horribly slow and cannot handle uploading large files. This is only very rough, using the ice photo as a base and then applying my normal mountain method to it. (which needs some polishing!) I noticed I had not named my layers while I was working but I do name them here. I hope that does not cause any confusion. Also I am using RobA's city colors palette here as a base. I use it all the time, thank you RobA! ;)
RobA's tutorial can be found here http://www.cartographersguild.com/showthread.php?1142-Award-Winner-Using-GIMP-to-Create-an-Artistic-Regional-RPG-Map and it is very much worth a read!

Search for ice photos or take your own. Save and open in gimp. If you are looking for mountains for a map you have already started it is quite easy to find ice photos with the right shape
http://i5.photobucket.com/albums/y181/Alvary/Mapping/MountainTute1.jpg

Do a basic crop, leaving the part of the image you want to use. Using a combination of color select and fuzzy select tool remove the unwanted areas of the image.
http://i5.photobucket.com/albums/y181/Alvary/Mapping/MountainTute4.jpg

You should end up with something like this.Clean up the last of the unwanted areas with the eraser. Fuzzy select the blank area, invert selection.
http://i5.photobucket.com/albums/y181/Alvary/Mapping/MountainTute3.jpg

Create a new layer (transparency) and call it "Mountain backup". With white as your foreground and black as your background, use the blend tool set to "shaped angular" to fill the selection. Duplicate and call the new layer "Mountain bump"
http://i5.photobucket.com/albums/y181/Alvary/Mapping/MountainTute5.jpg

(On layer "Mountain Bump") Go to colors - curves. I make the curve look somewhat mountain shaped, as this very much reflects in the finished mountains. I was pretty simple with it, feel free to play around. I also went to Colors - brightness and contrast and made a slight adjustment to the brightness, reducing some of the glare from the white. Then go Filters - blur - Gaussian blur. We just want to soften the hard lines here, 5 pixel was plenty on my small image.
http://i5.photobucket.com/albums/y181/Alvary/Mapping/MountainTute6.jpg

Go down to "Mountain backup" color select the outside and invert the selection. Create a new layer and call it "Mountain color". Move this layer to the top.
With a light dirt brown as the foreground and a darker brown/green as the background, fill the selection using Blend tool - shaped angular. Make it a little smoother using the colors - curves and Filters - blur - Gaussian blur like we did with the bump layer. I suggest duplicating this layer in-case you make a mistake and need to start a-fresh.
http://i5.photobucket.com/albums/y181/Alvary/Mapping/MountainTute7.jpg

I then bumped with a texture I have aside for this sort of thing. I will have to put up another tutorial on making the basic bumps I use a lot. Any fine rocky type texture will do, or leave it out if you wish. Once you have a texture you can apply it by going to Filters - map - bump map, and select the texture base you have made from the drop down menu.
http://i5.photobucket.com/albums/y181/Alvary/Mapping/MountainTute8.jpg

Now we get to see the whole thing come to life!
Select none. On your mountain color layer go to Filters - map - bump map. From the "bump map" drop down menu, select your "Mountain Bump" layer. How you set the sliders is up to you, I personally like to set the elevation quite high and the depth about half way (as you can see in the picture). This helps eliminate the terrible glare you sometimes get on the tops of your mountains if you set both a bit lower.
http://i5.photobucket.com/albums/y181/Alvary/Mapping/MountainTute9.jpg

And there we go, that is the base nicely done! To clean it up a little, go back to your "mountain backup" layer, select the blank area. Go select - grow selection. For this smaller image I grew by 2 pixel. Go back to your mountain color layer and add a layer mask (right clicking the layer in the layers box). On the layer mask, fill the selection with black. Invert selection and fill with white. Go filters - Blur - Gaussian blur. I did a 10 pixel blur. This adds a softness when you are using the mountain layer with other layers.
http://i5.photobucket.com/albums/y181/Alvary/Mapping/MountainTute11.jpg
This last image needs a little work, but it is 8am and below freezing and I REALLY have to get the fire going before my toes fall off...

I hope this tutorial was helpful. I certainly found the ice idea to work fantastically...using nature to create nature!
Alvary

Jaxilon
05-17-2010, 07:58 PM
What a "COOL" idea, hehe.

I might try this out one of these days myself.

Ascension
05-17-2010, 08:19 PM
Ingenuity strikes again. That's a great idea, man.

Alvary
05-17-2010, 11:24 PM
Another quick note...I have found that you can do much the same thing using photos of real large river systems.

I do find I spend way too much time making mapping easier and not enough making maps...

Ascension
05-18-2010, 12:41 AM
There's a lot of us around here who do the same thing...at least we're trying to make things easier. Usually without much success :)

tilt
05-18-2010, 05:19 AM
very nice idea... and it just goes to show that patterns repeat it self all over and you never know where you'll find your next idea.. :)

Steel General
05-18-2010, 08:57 AM
Interesting twist, thanks for sharing.

I would suggest you might want to compile the whole thing into a single .pdf and post it.

RobA
05-18-2010, 09:06 PM
So has anyone seen an L-System algorithm for generating frost crystals?

-Rob A>

waldronate
05-19-2010, 01:11 AM
Use one for a fern but stop after three levels, maybe? http://www.cs.unm.edu/~joel/PaperFoldingFractal/L-system-quick.html had a promising start point. At that point it's just a matter of applying a distance transform to the area outside of the fern and inverting it after clipping to a certain level.

Did I do a Wilbur tutorial on using the outside of river systems to make mountains? I can't remember; things are a little fuzzy lately.