lanlou123 / webgl-erosion Goto Github PK

An option to import \ export a heightmap will be nice if you find the time.
Thank you.

Hi, I found your code very useful for checking my own implementation of the Mei 2007 paper. In the process of implementing my own code I discovered that there are some problems with the original paper. You may find that the solutions I found will significantly improve the erosion results.

The first problem is with the axis alignment of the erosion features. This is caused primarily by the Mei paper ignoring the diagonal connections between cells, unlike the original O'brien paper from 1995. This makes it harder for fluid to move diagonally or other non-axis aligned directions. So fluid tends to flow in axis aligned directions when not impeded. You can easily add the diagonal connections by calculating 8 flux values instead of 4, using a similar approach to the axis aligned ones. To get the velocity you then add the diagonal ones to both of the existing X, Y components with a sqrt(2)/2 multiplier. I found that doing diagonal fluid flow completely eliminated any visible axis alignment of erosion features.

The second problem with the Mei paper is that they have a bad model of sediment transport capacity. They only include the slope and velocity in the calculation, but ignore the very important factor of fluid depth. In fact, the paper they cite for their sediment transport equation actually does include the depth, in the form of total flow q, which is equal to velocity multiplied with depth. I guess it is a mistake? By increasing transport capacity with depth, it creates a feedback loop where more erosion occurs in places with more fluid, which causes concentration of fluid and more erosion. This produces erosion structures like ravines and rivers much more easily than with the default equation. The new equation is just multiplied by depth (with a change in the capacity constant to compensate).

I think you can easily incorporate these changes, particularly the second one, which has a large positive impact on the quality of the results. The 8-way flux is not hard either, I implemented it just now in about 2 hours.

You can see the very nice results of these changes in the attached image, generated in about 3 seconds on 1 CPU thread.

Hello! This project looks amazing!

I'm trying to get the demo to work in order to share it with some learners at school, but none of the controls seem to work as documented. I made a small screen recording, I'm clicking on the terrain, pressing c on the keyboard, clicking "ResetTerrain"...

Nothing seems to happen. And no errors in the console. What am I missing?

This is in Chrome 94 on macOS 11.6

Thank you!

Rainfall modelling appears to be present in an older version (as shown in this video https://www.youtube.com/watch?v=_8y9peDmtwg) but seems to have been removed.

Could this be re-implemented, and what challenges are there in doing so?

I am very impressed by the simulator, I arrived here looking for a simulator capable of going back in time by estimating a reconstruction of the state of a territory in the past, considering erosion as the only variable. Do you know if there are researches in this direction?