Teasing masks from existing nodes in TG2 from a World Machiner

[Arandil]

Ok!  So it's Friday, I'm konked, but I'm also wondering about methods for generating masks out of nodes, fractal and heightfield terrain nodes in particular.  I was fairly comfortable with generating various masks using World Machine's tools, but I'm thrown off a bit trying to translate into the shader paradigm.  I'm not necessarily certain which shaders would function best in which circumstances, in the way that WM's node descriptions held more closely to a terrain based context as opposed to TG2's more unified design paradigm.

Any hints for a World Machine tweaker?

Thanks!

[bigben]

I use WM for generating masks, and while TG2 has a lot of improvements, WM is still very useful.

http://forums.planetside.co.uk/index.php?topic=864.0
This post looks at getting the correct result from image maps used as masks and may be of some help to you.

If you look at the node network from my main results section you might also get some more clues in combining masks.

As for using just shaders, here is  abasic example of what I do.
1: Create surface layers that will later act as the mask using just white and black (or greys if you want to get tricky)
2: Create a surface layer with the desired colour, removing its default fractal breakup
3: Bypass the mask "surface layer" and connect it to the fractal breakup of your surface, adjsuting these settings in your surface: Coverage = 0.5, Fractal breakup = 1
4: (optional) Insert a colour adjust shader to provide finetuning of the mask.

The attached TGDs demo each of these steps.

Having done this for each of your surfaces the other shaders that will be of use are the colour functions. These can be used to make combinations of masks from other surfaces for a different surface layer.  In my image mask fix post linked above, for example, I use a WM flow map image from which I subtracted steep slopes and high altitudes (distribution shader), from which I subtracted my water distribution mask (image of lake surfaces) to give me a density shader for my tree populations.

Hope this helps.

Ben

[Arandil]

Ben, thank you so much!  I got quite used to producing masks by filtering the height and slope of heightfields using WM, it was quite natural to me to work like that.  This shader business is a little trickier, but I'm starting to get results I like.  I'm going to go through your examples today.

Cheers!

[bigben]

I find it a lot easier to fine tune control over slope and height in TG than WM. The other main masks I extract from WM (other than flow maps) are north and south-facing slopes. These are really useful for setting differences in surfaces on the sunny and shady sides of a ridge/mountain which help to add a bit more realism.

[Arandil]

The north/south masking is a good idea.  After taking a gander at your examples, I think I'm going to experiment with using fractal terrain node outputs as mask sources.  I gather that it might be best to run these outputs through some other shader node before passing them to blender inputs on surface shader nodes, but I'll need to play around some to find out what works.

Cheers!

[bigben]

It may seem overkill to some but I've been drifting towards the same conclusion.  In theory it shouldn't really be necessary, but in practice it ensures correct masking of object populations, and it also provides a means of adding extra tweaks via child layers later on. It's easy enough to setup a clip file with your usual masking shaders for easy re-use later on so it's not really that much extra work.

[Arandil]

OK, I was able to get somewhere bouncing off of this discussion.  Thanks again, ben!
http://forums.planetside.co.uk/index.php?topic=912.msg8693#msg8693