View Full Version : How do I get good rivers in Wilbur?

10-25-2013, 08:20 PM

I have the above height map created in Photoshop (essentially clouds with some inverted Difference Clouds in patches to act as mountains). Now, I want to have as close as possible to 'realistic' rivers, but attempting to create these in Wilbur is a bit of a pain; I tried to follow the tutorial here Fun with Wilbur, Volume 5 (http://www.ridgecrest.ca.us/~jslayton/FunWithWilburVol5/index.html). First off, using 'fill basins' gets rid of all my lakes in the north; they just become flat land, which is not what I want. Then, I tried Texture > River Flow on the raw map, and I ended up with blue everywhere, essentially. It is a big map, 5k by 5k pixels in size, but does that mean I really can't get 'average looking' rivers? I've tried doing Incise Flow as well, as indicated in Fun With Wilbur vol 1, but that doesn't seem to do anything with the settings given in that tutorial.

I really don't want to have to come up with rivers 'manually', because that feels like cheating and it's not as realistic... so knowing how to properly 'riverify' this map would be great...

10-25-2013, 08:55 PM
Try selecting the land areas in Wilbur using Select>From Terrain>Height Range between 1 and 1000000 before doing the fill basins and river finding. I recommend using the fill basins / percentage noise / fill basins / incise flow sequence.

10-25-2013, 09:06 PM
That works out really well, actually. Can you give a quick explanation what all the parameters in Incise Flow mean? I think the sigma blur (first one) is the width of the channels, but that's all I know... Also, is there a way to fill these river channels with water after incising them?

It's been an age since I used Wilbur, and I can't find a way to export my 'coloured' maps; whenever I 'save as' and .png, it just gives me the alpha map which is fine, but I also want the coloured versions... unless there's also a way to assign gradients to alpha values in Photoshop, in which case I'll do that rather than keep struggling with Wilbur's gradient editor.

10-26-2013, 01:10 AM
Incise flow is a simple process that determines how many cells are upstream of a given point and then subtracts that value (raised to the Flow Exponent power and multiplied by Amount, but never more than the original altitude) from the current durface. The three blur values are constant-width blur before the variable-width blur and after the variable-width blur. The sigma values are approximately 2.5 pixel units, but not exactly.

If you'd like a river picture, use Texture>Other Maps>River Flow to color the river data onto the displayed image. Then, use File>>Save As and selection"PNG Texture" as the output type (selecting "PNG Surface" will save the height map rather than the colored image).

10-26-2013, 01:46 AM
Texture > Other Maps > River Flow still gives me random squiggles of rivers everywhere; I just wanted the Flow Incise channels filled with water...

So higher values of Flow Exponent and Amount would create deeper river channels, theoretically? And why three blur values rather than just one? Does that affect the beginning/middle/end of the channels respectively?

10-28-2013, 05:10 AM
The river flow operation needs to have contiguous rivers to figure out the flow. Try another Basin Fill operation after incise flow and before river flow to see if that makes any difference.

Once upon a time, there was only a single blur operation in there. Variable blur, however, resulted in some ugly pitting if used directly on the raw flow pattern (I need to put some more effort into that algorithm). The pre blur allows a blur to get rid of some of the noise before dong the variable, and the post blur is for cleanup n the variable blur. If you leave variable blur and post blur at 0 (using only the pre blur), then you get a single uniform blur across the surface. These blurs have nothing to do with the morphology of the system, except in a very oblique way as provided by the variable blur.