Big Empty Spot in PCG Tree Generation

The PCG graph is pretty simple — take the landscape and generate points, from those points subtract out the items tagged “Rocks” and the River Splines… I’ve eliminated the Rocks (it’s a bit jenky as it doesn’t seem to retain normal info but I digress).

Anyway this is the result. The white boxes (they look grey so the green ones cover the points) are the generated points and the green ones result of differencing with the river.

The blank space is a mystery as I HAVE NO RIVER THERE!

When I go into Landscape mode and select all of the river splines, I have no mystery river at that location.

Here is the PCG graph:

The net result is about 22,000 points and looks pretty good… except for that blank space. Here is another view of the blank space (in case folks were wondering if there was a cliff or something). Nope. Just flat land. White is the initial generated points and Green is the result after differencing with the rivers.

I’m open to suggestions and thoughts.

Well, I disabled the Transform Points (no change) and the Bounds Modifier (yup, that changed things) so now I’m puzzled that I don’t understand the Bounds Modifier.

I assumed (incorrectly) that I could use it to change the bounding box for each point on the river (i.e. increase/decrease the keep-out area for the trees). It appears that is also does some translation (I’m using SCALE). My assumption was that the points would remain at the same location.

(more editing)

Okay, I set the min x=1,y=1,z=1 and max x=5,y=5,z=1 and selected the PCG in the outliner. I also set the bounds to debug (blue) (extents).

This is not what I expected. Am I misunderstanding a key concept here? Do splines work differently?