Grasses striped on terrain

[rossworx]

I've been finding striped formations on grass clump populations I've placed in my landscapes, and I'm not sure why they come out that way. It doesn't seem to matter if I overlap different populations, even messing with their area centers, the stripes remain parallel, with varying degrees of terrain color visible to some extent. Playing with density shaders, inversions, and so on, merely change the assigned grass colors... Any suggestions as to why this is happening?

[Oshyan]

I would guess it is due to the size of your grass patches. The built-in grass object is actually a small planar surface with a definite area to it. It does not conform to your terrain's surface across a single instance, the best you can do is orient to terrain normal for individual instances (which I do recommend doing, to some degree). So with very rough terrain, as you seem to possibly have (judging by what I see on the right of the image), it is best to use smaller grass patches, each with fewer blades. This way each instance covers less area and you won't get large, planar sections that don't connect with the ground. It also looks like your populations might be floating, which may have to do with not being populated based on the final displacement of the terrain. You will want to connect your population's planet input to the final shader *that provides displacement* in your shade network, and in fact it's ideal to do all major displacement within the Terrain group *before* the Compute Terrain shader.

So, in summary, consider moving your displacement functions up in the network, and make your grass patches smaller and "lean" (orient) to terrain normal.

- Oshyan

[rossworx]

Thank you for your response. I have to acknowledge that I haven't yet managed to wrap my mind around direct node use; I go through the various menu options to achieve what I have so far.

I used areas of 1000x1000 on slightly variant centers. On total three sets of grass clumps, I had spacing (average) 3 and 2 with variations 2 and 1. The first two sets use clump diameter 2 with 1000 blades and (length 0.05 and 0.07), and the third set is diameter 6 with 4000 blades (length 0.08).  If I understand that part of what you tell me, these should work to keep their placement smooth, so I'm apparently missing the point.  I'm not too clear on the adjustments you recommend. 

In some areas, I note that some grass 'floats' against tree trunks and the rocky outcroppings (a happy -- I think -- accident with fake stones that led to the "Elftown' title). I suspect some of what you advise would fix that, too, if I could understand how to implement it. Is there a section of the tutorials that might apply?

[Oshyan]

I would guess that a diameter of 6 (which should be in meters) is rather too large and is probably causing - or at least contributing to - your problem. My first suggestion would be to reduce patch sizes down to no more than 2-3 meters. Start by trying that and see if it fixes the problem you've pointed out, or at least helps with it. You can adjust other things to compensate, if it does help, but causes other issues.

- Oshyan