For a very basic roughen filter similar to the already existing Distort -> Chalk and Sponge filter.

1. draw a line (2px)
2. open filter editor and click 'New'
3. find 'Turbulence' in the drowdown menu and press 'Add'
4. set the 'Base Frequencey' somewhere in the middle for a start
5. Add a 'Displacement Map' - here is the important bit: make sure the first triangle is connected to the 'Source Graphic' and the second to the 'Turbulence' above.
6. Give the 'Scale' a value of 20 for now and make sure X and Y Displacement are set to different channels !

Now you can play around with the sliders for different effects.
Octaves determine the complexity. The manual says, more than five dont do much.

This looks great and I might use the last one for a path on a map (the forest trail kind of path, not an Inkscape path!) I guess it'll be pretty hard on my PC though if I wanted several paths. I do want to give it a try so I'm leaving this comment so I can keep track of the thread. Thanks for sharing!

Thanks, thats good to hear ! I just thought we need to start somewhere small if we want to learn this stuff.

z3z wrote:I guess it'll be pretty hard on my PC though if I wanted several paths.

You could put the filtered paths on several layers and switch them off to give your processor a bit of rest.
And maybe use a bitmapcopy (Alt + D) as placeholder.

If you use a turbulence as type in the turbulence effect then you'd probably want to add an offset (of 1/2 displacement value if octave is 0) to counteract the sliding cause by the turbulence.
There's no need to offset if you used a fractal noise type

v1nce wrote:If you use a turbulence as type in the turbulence effect then you'd probably want to add an offset (of 1/2 displacement value if octave is 0) to counteract the sliding cause by the turbulence.
There's no need to offset if you used a fractal noise type

Thats interesting to know !
I thought about an offset too, after replying to z3z's post, maybe that could be added as a sequel to the tutorial.