In VNS 2, the relationship between vector-bounded Ecosystems, Environments, and Ground was often misunderstood, leading to confusion. VNS 3 represents a major shift in the way effects are rendered on polygons, with amazing results. Unfortunately, some users remain confused. Let's see how Ecosystem blending and Edge Feathering Profiles work with render order and how we can best use them.
Here's a planimetric view, 25 meters wide, of an idealized golf green. A Color Map image was draped for reference. We have a green and sand trap surrounded by grass and rough.
Here's an OpenGL view showing vectors for the green, sand trap, and grass.
With the Color Map disabled, the Ground renders. A bright color has been used to make it easy to see where Ground renders later on.
The terrain grid cell size is 0.5 m. At a Maximum Fractal Depth of 0, here's how the vector-bounded Ecosystems render in VNS 2 (top, with Hi-res Edges and Effect Resolution of 0.1 m) and VNS 3. Ground appears where Ecosystems are not placed by vectors. Whereas VNS 2 can only render a single Ecosystem per polygon, VNS 3 can render an unlimited number of Ecosystems on a single polygon. This is what 3D Nature refers to as Ecosystem blending. This blending of Ecosystems removes the need for Hi-res Edges and Effect Resolution controls.
Many users prefer Ecosystem edges to feather into each other in closer views. To soften the transition, a 0.3-m Edge Feathering Profile has been added to each Ecosystem using the default S-curve (top: VNS 2, bottom: VNS 3).
Profiles require higher fractal depths. In VNS 2, most of the render quality improvement was achieved at a constant Maximum Fractal Depth of 4, which took 30 seconds to render. With VNS 3, better results rendered faster (6 seconds) at a lower constant Maximum Fractal Depth of 2.
Using Environments to fill in Profiles
The question we often hear at this point is, "What's the yellow?" The yellow is Ground effect. An Edge Feathering Profile operates from the vector inward, revealing the next available Component on the render priority list. There are no other Land Cover Components in the project so yellow Ground renders.
If we want another Ecosystem to show through instead of Ground, we need to place it with a Component that has a render priority below vector-bounded Ecosystems and above Ground. Remember that Ecosystems can be placed in the following ways, in order of descending render priority:
If we want another Ecosystem to show through instead of Ground, we have two options. Our choice depends on how the existing vector-bounded Ecosystems function in the scene:
Both were applied in this render. A vector-bounded Environment with Rough Ecosystem encloses the vector-bounded Ecosystems and renders through their profiles. A global Environment with Woods Ecosystem (tan) renders everywhere else. While this provides a solution, it can mean creating several vector-bounded Environments to fill different areas and is limited by the amount of "filling" you can do.
Solving the problem with buffered polygons
If you have lots of shapefiles and plan to feather the edges, start with polygons designed for rendering with profiles. Shapefile polygons typically come together in a jigsaw puzzle and cover everything. It's either one polygon or another with no overlap. The most VNS-friendly way to use profiles is to use buffered polygons that overlap, thereby eliminating the need to "fill in" the profiles. In this render the polygon edges overlap and the Ecosystems feather into each other.