[Award Winner ] Creating an old-school map in Gimp.

[torstan]

Yep. Very simple really.

Take the final image which should really be a jpg file now. Open that up in Gimp. Now you want to use the colour select too, with a relatively high threshold - I used the following settings:
SeelctAColour.jpg

Now click on any white area, and you should get all the white areas selected. The threshold setting will determine how close the selected area is to the white/blue boundary.

Now create a new layer to play with. This should be transparent as before. We want to fuzz up the lines a bit. So go to Select->Distort... Now in this box I used the following settings:
DistortSelection.jpg

After running this filter, you'll get a slightly fuzzy version of your previous outline. Now, fill this with white (if white is the background colour still, this is as easy as pressing ctrl-.) and your map will now look something like this:
map8.jpg

How's that for you?

Obviously you can also fuzz the blue into the white areas. To do this, go to Select->Invert Selection (or ctrl-I). Then flood fill with our nice cyan colour (if cyan is still the foreground colour, this is just ctrl-,). I found that this was a bit too distressed so left that out of the above.

[Ghalev]

How's that for you?

Definitely close enough to start with; I can take it from there to get it exactly where I need it (more plate-blot/paper-bleed, mainly, to complement the grain and insure that no elements lose legibility).

Thanks very much. I like the look of Gimp, I just need to set aside a work-week sometime and immerse myself in it, get the feel of the controls ...

[torstan]

Well Gimp has noise (in Filter->Render->Clouds->Plasma), blur (Filters->Blur->... lots of options here) and contrast adjusters, though what you probably want is threshold (Colours->Threshold).

A combination of these would give a more fine-grained control over the end result than the crude selection distort I used above. In fact, you'd probably be able to carry the same method over from photoshop with no problem.

When you do throw yourself into Gimp I'll be happy to provide whatever pointers I can, and others here will do the same I'm sure.

[The Cartographist]

Torstan - Rep coming your way. Really appreciate the time that you took with this.

Question: Is there an easy way (other than going in and manually erasing throughout) of stopping the grid lines just short of the walls?

[torstan]

Yes definitely.

In your xcf file you should have a number of layers, one of which contains your walls. Now what you need to do is right click that layer -> Alpha to Selection. That should now have all your walls selected. Go to Select->Grow and pick a number of pixels. This number will be the number of pixels that the grid stops at before it hits the wall - essentially your padding. Here I used 5 pixels:
padding.jpg

Now create a new layer and move it between the walls layer and the grid layer:
padding2.jpg

With this layer selected, fill your selection with white (Edit->Fill with background colour if you have white as your background colour, or ctrl-. for quick). This should give you a nice white padding around your walls:
map9.jpg

Glad it was helpful.