Making Not So Random Coastlines in GIMP

[RobA]

After making a couple of random coastlines over here I wanted to make some less random coastlines. More specifically, I wanted to create random coasts in GIMP (or photoshop) based on a rough sketch of a coast.

I recalled a few tutorials on making lightning using noise and difference layers and figured I'd apply the technique here.

So what follows is a graphical tutorial on making "not-so-random" coastlines...

[RobA]

Changing the blur amount or the rendered cloud detail changes the effect.

It can also be used on any original shape!

Hope this was useful,

-Rob A>

[RPMiller]

COOL!! That is a really neat trick. I had done the "difference cloud" lightning thing before, but never considered using it this way. Well done! You deserve some rep, and thankfully I was able to give you some.

[ravells]

Brilliant! I always wondered what one could use the difference blend for, now I know!

Ravs

[Mercutio361]

Reppin' this! Thanks for this one. It's a simple but super-helpful lesson!

[WarBeer]

Hello RobA! Thank you SO much for all your GREAT tutorials I'm a bit "green" to all of this....but I'm really enjoying this site!

So, concerning the "Not so random coastlines" technique presented here. When I went with the 50px blur and full noise (using shape very similar to yours) I noticed that the fractalization could get a bit unrealistically random. So, I played with the values. When I reduced the blur to about 25px it was a bit more convincing on my image. However, I quickly realized that there were gaps/holes in the coastline. This of course slows down the filling process a bit. Is there something I can do to easily fix this? I'm guessing that the white from the cloud-noise must align with the edge at times?

[AriusAneid]

Really interesting technique! Just getting started out and this alone has made one of my first tries look much more realistic. Thanks for the information!