Edit: See also the second message in this thread about maps usage.I am working on User manual for
Classic Erosion, but decided to post here a brief parameters reference guide first.
I tryed to design parameters in such a way that the higher value of parameter leads to a more dramatic effect on eroded terrain.
Global parameters"Erosion scale" - defines the size of largest erosion features, for example, width of biggest gullies.
"Erosion duration" - defines the length of erosion process. You can set duration value higher than 1.0, but note that 1.0 is actually very large duration. Default 0.25 is enough for many cases, and often even lower values are successfull. For example, if you have already good-looking landscape and just want to add erosion signature for a natural appearance.
Example (based on Ulco Glimmerveen's setup):
Already good-looking mountain:
[attachimg=1 width=800]
Added erosion with duration = 0.15:
[attachimg=2 width=800]
"Auto calculate" - forces erosion shader to recalculate erosion upon the rendering if something has changed in the scene - erosion parameters or uneroded landscape. Erosion shader is clever enough to understand if changes in parameters or in the scene were critical and resapling or reeroding is needed. Still, in the some cases it can incorrectly reerode landscape even if nothing critical was changed, so if you faces such cases you can disable this parameter and be sure that erosion remains the same in any cases before you manually reerode the terrain by pressing the "Erode" button.
Heightmap tab
"Heightmap position" - sets the position of the center of heightmap.
"Heightmap size" - sets the size (in meters) of heightmap.
"Heightmap resolution" - resolution of heightmap.
Fluvial tab
"Fluvial erosion strength" - this is how strong fluvial erosion is. Can be set higher than 1, but this greatly degrates the erosion quality.
"Rock softness" - defines the speed of erosion process. The softer rock is - the faster is erosion.
"Downcutting" - controls the strength of vertical erosion. Downcutting forces erosion to form mountain ranges with complex drainage system.
"Base level" - defines when vertical erosion transforms to lateral erosion.
Parameters in "Special" section are quite exotic and are used in special cases.
Thermal tab
"Thermal erosion strength" - strength of thermal erosion
"Thermal effect size" - size of landscape features, affected by thermal erosion. See this illustration:
[attach=3]
I advice to set thermal effect size to 25 meters or even less. Larger values can be useful in some cases though.
"Min angle affected" - thermal erosion affects only features that are sloped at this angle or higher.
"Talus angle" - debris created by thermal erosion slide down forming talus with specified angel.
Rivers tab
"Rivers mode" - tweaks erosion algorithm so it become able to carve rivers. Note that when it is active many other parameters are disabled because they are controlled internally by Rivers mode.
"Headwaters density" - the number of headwaters per square kilometer.
"Lakes" - this parameters encourages rivers algorithm to form lakes, but it doesn't work as intended, possibly I'll remove it in future. Better if set to 0.0.
"Max rivers depth" - defines maximum depth of river in meters.
"Rivers width" - controls behaviour of river, encouraging it to form wider streams if amount of water is big enough.
Render tab
"Border blending" - controls the smooth transition between erosion heightmap and outer area.
"Render outer area" - renders uneroded terrain that is outside of erosion heightmap. Allows, for example, to apply erosion shader to selectively erode some area, leaving other terrain untouched.
"Render original HF details" - HF stands for high frequency. Renders original terrain details that are too small to be represented by heightfield.
"Mask by flows", "Mask by deposition", Mask by banks (in rivers mode) - prevents small details from being rendered if there is enough of water/deposition.
"Render water surface" - renders surface of water in Rivers mode. Note that this surface is still opaque, to render transparent water surface you need to add additional layer of water and to use "Water depth" map to restore original river bed. I'll show later how to do it.
Maps tab
"Enable maps" - enables maps outout. Maps are output into color output of shader and can be separaed using "Red to scalar", "Green to scalar" and "Blue to scalar" Terragen functions.
"Red", "Green" and "Blue" parameters - assign map to corresponding color channel.
Available maps are: flow map, deposition map (banks map in rivers mode), wear map, streamline map and water depth map.
Streamline map is special map, displaying streamlines in flows. Can be used for texturing glaciers ("Laminar flow" can be useful for it):
[attachimg=4 width=800]
Mask tab
"Mask by shader" - enables masking of erosion using selected shader, plugged into "Mask" input of Classic Erosion shader.
"Invert mask" - inverts mask input.
"Masking mode" - switch various masking modes. Available modes are:
- "Mask as blend" - classic blending mode, blends uneroded and eroded terrain;
- "Mask as erosion strength" - allows mask input to control erosion process by treating mask input as erosion strength;
- "Mask as rock softness" - the same as above, but mask controls rock softness;
- "Mask as precipitation amount" - mask input controls amount of water rained to the terrain at various areas.
HDD tab
This tab allows to store erosion data into specified file and restore in in the future.
"Erosion data file" parameter with "Save" button. Saves the erosion data upon pressing the "Save" button and stores the data filename.
"Read erosion data on project loading" - loads the file specified in "Erosion data file" parameter when the scene project file is opened.
"Read now" - loads data file immediately.
Daniil.
