Suggest some further mention of -r parameter in documentation

[nigels-com]

Hello, and thanks for the map generator. Nice.

Just some feedback about how I went with this.
I puzzled a little, getting suitable results at higher resolutions:
4096x4096, 8192x8192 and 16304x16304

-r 0.04, 0.02 and 0.01 are the values I settled on, after some trial and error.
It does seem to slow down more than 4x with each doubling,
Possibly some performance improvement possible at >1M samples.
Such as multi-threading, possibly.
(I didn't look into that, just to mention)

As synthetic data generator for mapping applications, very much appreciate this project.

[Azgaar]

Hello, Sorry, but I'm not following, what do you mean?

[nigels-com]

For a less technical user, it is less than clear how to choose the value of r. Perhaps if unspecified it should be inferred from the output image size? Sqrt(width*height) * factor. Perhaps inversely proportional to the number of pixels.