vec_build_overviews: Build overview pyramids for a .vec raster

In vectra: Columnar Query Engine for Larger-than-RAM Data

Build overview pyramids for a .vec raster

Description

Appends n_levels - 1 reduced-resolution copies of the raster to the file. Each level is computed by 2x downsampling the previous level with the chosen kernel. Reading via vec_read_window(level = L) picks tiles at level L; the file's n_levels is updated in place.

Usage

vec_build_overviews(
  path,
  levels,
  resampling = c("average", "nearest", "bilinear", "mode", "gauss"),
  compression = c("fast", "balanced", "max")
)

Arguments

path	Path to a .vec raster file. The file is modified in place.
levels	Total levels including level 0 (so levels = 5 adds four overviews: levels 1..4). Must be in ⁠[2, 16]⁠.
resampling	One of "nearest", "average", "bilinear", "mode", "gauss". "average" is the right choice for continuous rasters; "mode" for categorical/land-cover.
compression	Compression effort for the new tiles. Defaults to "fast" because overview tiles are usually one-shot writes.

Details

Unlike the streamed raster verbs, this decodes every band of the base raster into memory at once to build the pyramid, so peak memory is on the order of the full base raster (all bands). Build overviews before a raster grows past what fits in RAM, or on a per-band basis for very large stacks.

Value

Invisible NULL.

vectra documentation built on July 31, 2026, 1:07 a.m.