Masking tree populations by age

[bigben]

It's coming along well.

I'm not too sure about the stripes of "grass" in the foreground. It looks a little odd to me. Using the tree populations density shader to provide a mask for different grass under the trees is a good idea.  The scale still looks a little odd although the bridge obviously fits the terrain where it's supposed to be.  Maybe the tree desnity is a little low?... or perhaps some other detail along the shore might help provide a better sense of scale?

The distant hills are looking nice.

[gregsandor]

I like the way the background hills look, and agree about the foreground.  The trick will be to get the near stuff looking nice and retain what I like about the distant mountain cover.

What we have now is the low-density tree mask.  I've just made a high density one: same way, by tracing the orthophotos.  That will contain the heaviest concentrations of trees.  Setting that up after I brew a pot of coffee...

The grass distribution is a copy of the tree dist, using a world-machine generated Rivers mask.  Heres a test shot before I put the textures in.  Red will be darkest grass, Yellow, mid, and blue, lightest.  This render is before restricting by slope or altitude.

Now for the heavy forests...

[bigben]

Flow maps can be very effective, even if used subtely. You might also want ot combine them with some other variations (e.g. interaction with tree density) to provide a bit more variation. Combined woth your slope variations this should produce a very nice image.

[gregsandor]

What kind of interaction with the forest density?

[bigben]

e.g. add a % of the old tree mask to the dark grass mask to increase the amount of dark grass around the trees independent of whatever is happening with the grass mask.

[gregsandor]

Ahh, okay. 
Here's the current state with the new Dense Forest layers visible in upper left and right (populations of Young, Mature, Old with increased densities, using the DenseForest masks.

[bigben]

The other thing to consider is the resolution of your mask image in relation to your terrain.  The antialiasing in TG will reduce the density across much of a low resolution image. You should use a resolution where the smallest detail you want to retain is 2 pixels wide in your image.  Even then, you may want to use a colour adjust shader to increase the contrast slightly to get your values up where you expect them to be.  Most of my masks are at least 10m/pixel for close up work derived from landsat imagery, or 30m/pixel from USGS canopy data.

[gregsandor]

The mask for the 23040 m terrain is 2048 x 2048, as is the one for the 2565 m terrain.  This gives resolution of 11.25m/px for the 90m dem, and 1.25 m/px for the 5m dem. 

[bigben]

At 1.25m/pixel you could turn off antialiasing for the mask image for the population.

Another interesting thing to try would be to use a 2 pixel wide brush to place white dots where you want trees (on a black background) and try an object spacing somewhere around 4. You might be able to "place" individual trees reasonably close to where you want them.  Haven't tried it myself but it would be an interesting experiment.

[gregsandor]

Is the antialiasing option in the image map dialogue?

I have used the method you describe.  I'll see if I can find an example for you.  It works.

[bigben]

Is the antialiasing option in the image map dialogue?

Yes.  In the colour section

[gregsandor]

This is Augusta County, Virginia.  In the high-res orthophoto I located the bases of all the telephone poles (look for the end of the shadow) and placed a dot, then used the processed result to mask the population.