Am I able to create an alpha map for MASH distribution?

[JacksonLamme]

I like the paint vertex option for mash that lets you flood white then paint black where you don't want the trees to populate, but I'm trying to fill an area in a snapshot from google earth and I would like to be more precise.  Ideally I want to create an alpha map in photoshop then have the distribute follow that guideline.  

The paint vertex option also paints the whole mesh so all I see is black and white until I render, I would prefer to see the original colors.  The way I'm doing it is to duplicate the mesh and create a locked transparent layer above the white painted mesh so I can see the topographical photo while painting on the target mesh.  

[damaggio · Accepted solution]

Have you tried the Mash visibility node and then just apply your texture map from google in black and white since it has the vegetation area already? alternatively under visibility you can also create a "map helper" plane(similar to what you have done so far) and paint over the surface in Xray mode if needed.

You have a good resolution 4800 image already to use , just play with Photoshop levels in BW  or do it on the fly with a remapHSV node in Maya.

[JacksonLamme]

It looks like strength map under visibility node may be just what I need!  Many thanks.  

[JacksonLamme]

As an update I was unfortunately not able to get it to work properly.  It just doesn't follow closely and isn't sized correctly. I did get a great map in photoshop by greyscaling, replacing colors, then inverting. It works with a simple circle but not with a complex strength map. 

I saw something online about being able to map the vertices with a texture, perhaps that will work.  

[damaggio]

Hi Jackson, "It just doesn't follow closely and isn't sized correctly" , it should match precisely since you already have the texture map that matches your UVs.

Could you explain better what you mean.

[JacksonLamme]

I'm not sure what happened with the strength map, I couldn't find a workaround but as you see from the photo it was not applying properly.  I had more success with uploading the image as an attribute map in the paint settings.  It recognizes the big areas like the lake, but as you see the small areas are virtually ignored by MASH, and it even looks denser in the dark areas.  I'm satisfied because I can probably subtract some of my 1 million trees using a placer node (?)