[Award Winner] Fun with Wilbur, Volume 1

[waldronate]

I see what you're saying there Waldron. Strangely, while I'm pretty well grounded in the math, I have a lot of trouble visualizing the results.

I'm curious is there any way to get a mask of basin areas from the Fill Basins filter? Failing that, and perhaps more generally useful, could you have a 'Select Flat' option. That is a selector that scans a window around each pixel(say 3x3) and selects that pixel if and only if all points within that window are within a given variation(epsilon?) of each other. Then you could noise up the supernaturally flat basins while leaving the yummy ridginess of the mountains pristine.

I wasn't initially sold on the terracing produced by the Remap Altitudes, but I like how the Precipiton mostly beats that down. It also erases a lot of the streambeds. Another thin Incise Flow at that point might be nice. (?)

Anyway this deserves a rep.

One way to select flat items is to use a shader trick. In the Wilbur shader, set the land color list to one white color and the Intensity to be 90 degrees elevation with 1000 vertical exaggeration. Then all flat (or nearly flat) areas will be white and all non-flat areas will be black. Texture>>Transfer>>Texture to Selection will make the selection from the displayed image so basins will be selected and non-basins won't. I agree, though, that it would be nicer to have an option such as you suggest that would perform this trick in one step.

[RobA]

Clever!

I'll have to remember that one!

So when transferring a texture a selection - white is 100% selected and black is 0%?

-Rob A>

[waldronate]

Correct. It's an 8-bit alpha (opacity) channel.

[su_liam]

It turns out my old version of Wilbur(something like 1.54, I think)had some serious problems with Incise Flow. After spending most of the evening d/ling the new Wilbur version(and the entire .Net framework, apparently), I found out the Cow Machine with it's fully paid off copy of Win98 was unable to run that new version. Maybe I'd be better off getting an emulator for my mac. It couldn't be any slower than the 20th Century POS at work.

I would be interested in an explanation of some of the controls in this program, particularly Flow Exponent and Effect Blend in Incise Flow. Also is, H in your heightfield generation equivalent to Persistence? In that case, an H of 1 would mean each octave is of constant amplitude but 1.9 times the frequency of the previous(for a Lacunarity of 1.9, anyway).

[waldronate]

It's good to know that the current Wilbur version doesn't work with Win98. I have updated the web page to indicate the new information. It's probably the OpenMP stuff.

The way that incise flow works is that it computes the number of pixels uphill from the current pixel for every pixel. The amount of height removed from the surface at each point is proportional to the flow raised to the Flow Exponent power. Smaller values give a more pronounced effect. In the real world fractal river networks tend to have a fractal exponent of roughly 2/3 (or 0.666667). Effect Blend is the amount of the result that's blended with the existing image. 0.5 uses half of each, -1 gives river networks that come up out of the ground rather than going down into it and so on. I need to get back to updating the documentation and/or writing a real help file.

H in the fractal functions is out of the original Ken Musgrave code. It is a measure of the roughness of the surface. H is the name of the variable, most likely derived from the Hausdorff-Besicovitch dimension, or fractional dimension.

[su_liam]

Haha! I found an archived copy of the old version of Wilbur on the Cow Machine last night. Yay!

I guess my problem with Incise Flow was that I was using a global map. The erosion tools don't seem to like that. I did a nice little quadrangle and bang(!)... beautiful.

Now I just need to save pennies for an Intel emulator, and see if Wilbur runs on WINE. I know I do

[arsheesh]

Just wanted to say thanks for making this software available Waldronate. I'm really new to Wilbur but with the help of your tutorial and some trial and error I've been able to use this program (along with GIMP) to create my latest map. While there's room for improvement, I am really happy so far with the results I'm getting with Wilbur.

Cheers,
-Arsheesh