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Thread: exploring erosion

  1. #1

    Default exploring erosion

    it took about 45 minutes for this process lol so i thought i'd share my (mis-)adventures..

    ..my intent is partly to implement a realistic looking erosion procedure and partly to simply try stuff and see what happens and what i learn from the experience..

    after researching various documented erosion algorithms my first step was (and will be for a few more attempts) to see what results i get with the simplest implementation. the first simple implementation wasn't so good, but maybe i can combine it with other things later..

    here's a bit of my standard musgrave's ridged multifractal implementation.. 8 octaves, lowest two aren't ridged..
    naiveerosion0.jpg

    and the result:
    naiveerosion1.jpg

    this postulated erosion drops random raindrops with n amount of soil moving capacity. this moves from pixel to pixel (contiguous 4) until the "drop's" capacity is depleted. deposition was calculated by taking the height difference (an INT in this implementation) and performing a modulus by a static value to determine the amount of material displaced between the two pixels. loop this until out of capacity or no lower pixel. there is no other differentiation, eg. above or below water, slope to neighboring pixels et c.

    i know that's really crude but the goal was to see what results are possible with the simplest methods first... in case you decide to try this yourself

    ftr i think the 'take a modulus by n' strategy is bound to leave artifacts eg. on ~linear slopes, but in practice the results weren't as bad as i expected. while this algo did effectively fill basins, it really did "slump" the heightmap as if it were sand.. removing much of the detail it would be preferable to retain.

    if i attempt other methods i'll add them to this thread, with a pragmatic description of the method and intent fwiw.

  2. #2
    Guild Artisan su_liam's Avatar
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    Default

    Shocked it took me this long to see this.

    You're probably going to see more artifacts from four way flow than the mod n. I'd have the erosion increase with slope and decrease a lot under water. Deposition should probably be at a maximum on flat surfaces, decrease with slope and increase under water.

    Another improvement once you have slope variation and especially eight way flow, would be a separate hardness raster. Harder surfaces reduce erosion, softer surfaces increase erosion. Hardness wouldn't effect deposition.

    I'll watch this with great interest!

  3. #3

    Default

    the project is gradually subsiding to the fact that waldronate has done all the work already.. my interest in developing is now more an obstruction to using an available resource..

    did open it up yesterday to add nonlinear shaping to the musgrave's ridge foldover.. i was looking at my ridges all being along the centers, cubed the folded contour and raised the unfolded with n*(2-n). it's not a miraculous difference but it works alright.

    given how intensive the particle erosion was, most of my further thoughts given the preconditions for my app have involved less heavy duty, cheesier solutions :p like i'll probably stick with the shaped ridges, then n*n land above sea level and generate rivers from random points instead of mapping.

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