Heightmaps & Virtual Arrays

The idea

A heightmap is a grayscale image of elevation: a 2-D grid where each cell holds a height value. Brighter = higher. Most nodes in Hesiod take one or more heightmaps in and produce a heightmap out — that is the data flowing along the wires in a graph. A few nodes convert to other types: a colouriser, for example, takes a heightmap in and produces a texture (an RGBA image) out.

graph LR
  A["Noise<br/>(primitive)"] -->|heightmap| B["Erosion"] -->|heightmap| C["Colorize"] -->|texture| D["Export"]

Most wires carry a heightmap from one node to the next; the colouriser is where the data turns into a texture. Matching wire types matters — you cannot feed a texture into a node that expects a heightmap.

Heights live in a normalized range and the terrain lives in a unit square ([0,1] × [0,1]); real-world scale is applied only at export. This is why the same graph behaves the same at any resolution. (Details: Coordinate system.)

How Hesiod handles it

In the node reference you will see ports typed VirtualArray (the Inputs and Outputs tables). A virtual array is Hesiod's representation of a heightmap — the value that flows along the wire from the node that produces it to the node that consumes it.

See also

• Node reference — every node's input/output heightmap ports.
• Tiling & overlap — how a heightmap is computed in pieces.
• Coordinate system — the normalized domain.