[Award Winner] Technique for adding coastal detail as you zoom in.

[RobA]

@dr-spangle:

Are you blurring the original enough to give the clouds layer something to work with?

Can you post up the starting image, too, so I have a better idea of what you are working from?

-Rob A>

[dr-spangle]

A friend did that copy, erm

Here's one I did with similar results.
Start: http://80.42.27.104/zoomed%20maps/base.png

Scale up 500%
http://80.42.27.104/zoomed%20maps/Try%206/2.png

Blur:
http://80.42.27.104/zoomed%20maps/Try%206/3.png

Create cloud layer on burn
http://80.42.27.104/zoomed%20maps/Try%206/4.xcf

Merge down:
http://80.42.27.104/zoomed%20maps/Try%206/5.png

Threshold:
http://80.42.27.104/zoomed%20maps/Try%206/6.png



Both this one and the one my friend did are parts of this map:
http://www.micras.org/maps/blank.png
I use black for land, he uses black for water, both images are part of the central continent.

[Redrobes]

Try it this way then. Take zoomed up coast in black and white and blur it a bit. Get some fractal clouds noise and add enough contrast so that it spans the range from black to white burning out a little at each end. What I have labeled lumpy noise. Then take that noise and adjust contrast by -20% so it spans from near black to near white. Then 50:50 average the blurred coast and the new noise. Then ram the contrast right up to 100% to get black and white again.

All that you are doing is just modulating some noise on top of the coast. By averaging in some noise on the blurred edge of the coast then it pushes it over and under the mid level and then when you whack up the contrast again its takes it back to black and white with crinkly noisy edges.

[dr-spangle]

Ok, that works for a small area, but the clouds are not dense enough when I do a large area like 1000*500, I'm limited to something like 200*200 squares...

If I zoom the original map by 5 times, the map will be 18000*9000, which would have to be broken into 200*200 parts, of which there would be 4050

[Redrobes]

These techniques will work at any size. I guess your having trouble getting some noise at the right scale and density. I am sure Gimp will be able to do it but I don't use Gimp - I use imagemagick which is also free.

Install imagemagick, open a command line - run cmd.exe and type

convert.exe

if that gives a huge list of image options then its installed ok. If it talks about converting drive formats from DOS to NTFS or whatever then its not in the path correctly so add the full path to the file like

C:\Apps\ImageMagick\bin\convert.exe

until you get image options. Then paste this into it modifying the convert to the full path version.

C:\Apps\Imagemagick\bin\convert.exe -size 512x512 xc: -type Grayscale +noise Random -resize 4096x4096 -contrast +noise Laplacian -blur 2 -contrast C:\MyWorkingArea\noise.png

that will give you a 4K x 4K noise map like this.

[RobA]

Mentioned in another thread-

Get this noise generator: http://fimg-gmplugins.sourceforge.net/

It can produce many more options at better resolutions, and absolute pixel sizes, as opposed to being relative to the image size.

-Rob A>

[dr-spangle]

Well, I'm on linux, and that option by RobA appears to be windows only...

I'm having a little trouble with imagemagick, but I should be able to install it on apache on here later today and get something through that... possibly

[isomage]

Well, I'm on linux, and that option by RobA appears to be windows only...

It has source code which looks like it'll compile under linux -- get the .tar.gz.

I'm having a little trouble with imagemagick, but I should be able to install it on apache on here later today and get something through that... possibly

Shouldn't need a web server -- Redrobes's use of Imagemagick was command-line.

[isomage]

It has source code which looks like it'll compile under linux -- get the .tar.gz.

I just compiled it on Ubuntu 8.04, and I only needed to install the GIMP development package, libgimp2.0-dev.

I also tested the ImageMagic instructions; note that Redrobes's instructions are for Windows, so you need to use "convert" instead of "convert.exe" and specify a Linux path for the output instead of "C:\..."

If you're getting errors, let us know -- someone here might be able to help you get set up.

[dr-spangle]

dr-spangle@dr-spangle-laptop:~$ convert -size 512x512 xc: -type Grayscale +noise Random -resize 4096x4096 -contrast +noise Laplacian -blur 2 -contrast /home/dr-spangle/Desktop/noise.png
convert: UnrecognizedNoiseType `Random'.