Prune Grid Node

The Prune Grid node optimizes the storage of a voxel grid by collapsing uniform regions into coarser tiles or inner nodes, reducing memory usage and improving performance.

This node performs the inverse operation of the Voxelize Grid node. While voxelization expands sparse tiles into dense voxels, pruning detects large uniform areas and replaces them with more compact representations. This is especially useful after operations that create large regions of constant values, such as filling, clipping, or thresholding.

Inputs

Grid

The input grid to optimize.

Mode

The pruning method used to simplify the grid structure:

Inactive:

Turns inactive voxels and tiles into inactive background tiles. This is the simplest mode and provides basic cleanup for grids with empty or unused regions.

Threshold:

Collapses regions where all voxels have approximately the same value and active state (within a given tolerance threshold) into background tiles. This is useful for fog or scalar grids where smooth variations may leave near-uniform areas that can be simplified.

SDF:

Specialized mode for signed distance field (SDF) grids. Replaces inactive tiles with inactive nodes, providing faster and more targeted pruning without the need for threshold comparison. This mode is efficient for narrow-band SDFs that contain large interior or exterior regions of constant sign.

Threshold Threshold

Voxels within a region are considered uniform if the difference between their values is less than this amount. Higher thresholds allow more aggressive simplification, while smaller values preserve finer details.

Properties

Data Type

The type of data stored in the grid (e.g. Float, Integer, Boolean, Vector). Must match the type of the input grid.

Outputs

Grid

The resulting grid with optimized storage. Uniform regions are collapsed into larger tiles or nodes, resulting in a more compact and efficient representation.