Hey DT, thanks, yes a river plugin would be nice, but I think that is way over my head,,,I spent a very long time trying to get to grips with javascript for the upcoming ME-DEM Google map (so far 4 layers deep , 575 meg, sitting on my local machine server), and I am still fiddling with xml for MS Virtual Earth/World Wind/ and Ceaser.
Saga Gis itself is open source, so (I think) all the "math" is available within the source download package, but I have never browsed through it,,,I probably should. I have no idea how one would sset a plugin up, but I do have some basic (
very basic) idea of what may be needed.
Saga uses a heightfield and a grid system (which defines the extents/size of the heightfiled) as the base for all calculations.
I then run the Preprocessing modules Sink Drainage Route Detection and Sink Removal(deepen drainage routes). My understanding of this Sink Drainage Route Detection bit is that the algorythm(?) uses the grid and heightfield and then identifies the height of a given pixel, finds the escape route from that pixel to one which is lower, and continues on until the edges of the heightfiled are encountered. Then each pixel is identified with a numeric between 0 and 8 which identifies the direction the flow escapes, If you run this module in saga you wil get a nice image showing the routes, in order to see the numeric identifiers you must zoom way in.
Sink Removal(deepen drainage routes) uses the grid, heightfiled and the results from the Sink Drainage Route Detection to identify blockages and then lower them to connect existing Drainage routes. It does a pretty intelligent search, connecting the closest routes . Depending on the heightfield in use you can end up with some pretty deep canyons.
I have run some hi res real world dems of Northern New Hampshire, where I grew up, thru Saga and it did a real good job of identifying old dry stream beds and , for some reason, railbeds, that i remember...so i would expect it to give realistic output of fictional heightfields.
After that it would get a little more difficult to decide which way to go for algorythms, I like the ones that produce the wetness index, LS-Factor, and catchment area, because the png's are easy to visualize as watercourses (they have a nice sinouos appearence and vary in color) and to manipulate in PhotoShop , but I have no idea how they operate or what they require to function as far as other info at the moment, everything is on the main comp ( I guess I should look)..
And then the question arises of how to manipulate that data within L3DT to alter the heightfieldd ( as manipulating it in Photoshop before mergiing in Leveller as a second heightfield does). Slider inputs to vary the greyscale range, numeric input to set the min as a negative height and the max as zero,,and the subtract it from the original heightfield...erosion masks ala WM.
So I guess I really should look a little deeper, and then come up with a better idea of what is needed.. and continue after going to by balloons for my rather insitent 19 month old boss. Seer
Blue