[Award Winner] Making Not so Random Coastlines in GIMP - alternative method

[aeronox]

The Threshold tool in Photoshop is under Image -> Adjustments (down the bottom)

The Render -> Clouds filter in Photoshop is too large, so I used GIMP to make one (I selected "Tileable" and filled it as a pattern, because I needed smaller details in a larger-res map)


A nice use for this method - increasing detail (the opposite of generalisation). So you have a low-res large-scale map, you can first apply the "Not-so-random" effect at that scale, then resize the image, blur a bit, and repeat. It can give you increasing levels of detail, much like the way real cartography works. It's not perfect, but it's close enough.

[RobA]

A nice use for this method - increasing detail (the opposite of generalisation). So you have a low-res large-scale map, you can first apply the "Not-so-random" effect at that scale, then resize the image, blur a bit, and repeat. It can give you increasing levels of detail, much like the way real cartography works. It's not perfect, but it's close enough.

Surprisingly, that is something I have been using this technique for, without mentioning it here! I find keeping the blur small and choosing the turbulent option in the gimp render clouds help maximize the randomization while keeping the overall shape reasonable accurate.

-Rob A>

[OneSeventeen]

First post here.

I tried to work this out in Photoshop and had no luck. In general, I would get too-smooth edges on my shape. Is this because the clouds aren't... rough enough (as you can't change them in PS)? I love this idea because of the success I've had with using clouds for general randomness. Suggestions?


117

[RPMiller]

Welcome to the Guild 117! Always glad to see new members. I believe you hit on the primary cause of your frustration. I'm trying to figure out a possible solution for the problem, but I'm not sure how soon that will be.

[aeronox]

I downloaded GIMP solely to create the noise pattern.

Open GIMP
Make a blank image something like 800x600
Filter -> Cloud/noise it at maximum
save it
open it in Photoshop (the copy/paste seems to not work between the two programs)
go to Edit -> Define Pattern...
go back to your map
set your blurred-map-shape layer to "Multiply"
create a new layer underneath it
now use the bucket, set to "Pattern", and fill. (i actually applied it as a Layer Style, so that I could adjust the pattern scale)
Ctrl+U to adjust the lightness, bringing it up so that the darkest grey is around 25%.
merge the two layers
go to Edit->Adjustments->Threshold

it takes some trial-and-error, with the amount of blurr to your map-shape, the scale of the clouds, lightness of the clouds, and the threshold slider. just give it a few goes.

[RobA]

Wow Aeronox - Gimp is pretty heavy just to generate noise

Have you tried any third party plugins? I quickly found one called Clouds 2.2 half way down this page. It is an .8bf filter (works fine using the pspi plugin in Gimp) that has a few nice presets for clouds, and can generate very fine cloud turbulence.

-Rob A>