Random Density Map GIMP Script

[RobA]

As hinted here I have been working on a gimp script to draw with the active brush using a "density map" to determine the probability of painting.

Attached is a zip. Just drop it in the gimp script directory.

Here is where it registers in the menu:
menu.png

Do use it in the most basic way, create a probability density map.... a layer where back will have a 0% chance of drawing and white will have a 100% change of drawing:
map1.png

Create a new layer (it must be the same size) to draw on with the current brush.

Here is the dialog:
dialog.png

and one result with a red Hexagonal 21 px brush, and set it at 100% Density, Spacing of 21 px, and no Jitter:
1-nojitter.png

(more examples following...)

[RobA]

Using the same Density map, here are more results:

Setting the density to 50% will make white only have a 50 chance of drawing. Here again with no jitter:
2-nojitter_50percent.png

And back at 100%, but with a jitter of 1. The jitter value is a scale of the spacing parameter, for randomly displacing the x&y directions, to get rid of the grid look:
3-jitter.png

The scrip draws left to right and top to bottom, to work with isometric image brushes, like the trees posted:
4-trees.png

And using the "invert" check will invert the map (black = 100% chance and white = 0% chance):
5-trees_invert_map.png

(cont...)

[RobA]

The other option is less useful for mapping but might have some artistic uses...

You can use a map with transparency, and it will use the alpha as the density map, and the colour as the colour to paint with.

Here is such a density map:
map2.png

and the result, using the hex brush again:
map2_result.png

Enjoy!

-Rob A>

[ravells]

Rob that is phenomenal! I wonder if it's possible to write a script that does this in photoshop?

[Ghalev]

Excellent and useful stuff.

[jfrazierjr]

The drool is running down my chin as I type. This is GREAT. I can't wait to try it out.

Joe

[su_liam]

Cool. I'll have to try this. It looks like you might be able to use the alpha-and-color option to cause interesting variation in tree(or mountain or whatever) color. For instance, with trees, create a layer with a narrow variation of green shades. (Possibly use a greyscale fractal and gradient map with a narrow gradient(say dark green to light green)).

Another idea I have is to make an initial color layer that varies only in hue and saturation, and apply a variation in value by multiplying with the shaded relief from an HF.

Then you paint in your desired forest density in alpha.

Might be a good way to add an interesting forest texture to a shaded relief map.

I was initially thinking of using top-down trees for a realistic look, but I think this might work best all symbolical, with iso trees simply as a symbol saying, "forest here."


If nothing else, this is making GIMP look like a more and more viable alternative to CC for "symbol"-type maps.

[RobA]

One limitation is that it doesn't respect active brush scaling, so all images are drawn at the original scale of the selected brush. Initially, I hoped to have an options to paint smaller versions based on the density map, but dynamic brush scaling isn't exposed in the scripting API (yet).

-Rob A>

[The_Mighty_Eagle]

Using the same Density map, here are more results:

Setting the density to 50% will make white only have a 50 chance of drawing. Here again with no jitter:
2-nojitter_50percent.png

And back at 100%, but with a jitter of 1. The jitter value is a scale of the spacing parameter, for randomly displacing the x&y directions, to get rid of the grid look:
3-jitter.png

The scrip draws left to right and top to bottom, to work with isometric image brushes, like the trees posted:
4-trees.png

And using the "invert" check will invert the map (black = 100% chance and white = 0% chance):
5-trees_invert_map.png

(cont...)

Is there any way to make it draw on another layer than the density map?

[Seraphine_Harmonium]

This is a great idea. I noticed though, that you have trees in various colors. How do you get this to happen?

When I first tried to use this, I was using transparent brushes, which I have found doesn't work if the density is greater than the very sparse. I ended up layering color behind one, merging down, and making a brush from the clipboard, but the trees all look identical that way. In your example there is at least color variance. Is this a difference in how I am implementing the script, or did you recolor them afterwards?