How it works
A voxel is a pixel with depth: one box of a 3D grid. Voxel maps (Minecraft, MagicaVoxel,
and lately whole cities in three.js) build ground out of them. Here the ground is the GEBCO 2026
elevation grid, land and sea floor, cut into columns, each the mean elevation over its
footprint, rounded to a whole number of voxels and stacked from a common floor.
Columns across is the resolution. Sliding it, or Sweep, is what a stack of
overviews does to the same ground: each halving merges four columns into one. The readout names the
GEBCO level read (the file carries its own overviews, 15 arc seconds and coarser) and how many
samples each column averages. Past the source's own cell size, more columns add no detail: they
repeat the same ground in smaller pieces.
A voxel is only a cube in some coordinate system. Cells picks it. Lon/lat cells drawn square
is the array as stored: equal steps of degrees, the way GEBCO is. At their true size on the ground
the same cells narrow from east to west away from the equator (by the cosine of latitude), so the rows
step in at the edges and the block leans toward the pole; at Ross Island a cell is nearly five times
taller than wide. Square cells in metres resample the ground onto a Lambert azimuthal equal-area grid
about the centre, where every column has the same footprint: the voxels are cubes on the ground.
The vertical is its own choice. At true scale a voxel 500 m wide and 100 m tall is a slab, and
most terrain is flatter than it looks on maps; Cubes exaggerates the heights by the ratio of
cell to voxel height, so the blocks read as cubes and the readout says by how much. Heights are
GEBCO's, metres above mean sea level (so above the geoid, see the Geoid
page), and Water fills the sea to zero.
GEBCO stops at about 460 m. Over Tasmania, once the columns are finer than 500 m, the land comes
from the state's 2 m DEM instead, a cloud-optimised GeoTIFF in MGA zone 55 read in place like GEBCO:
only the window under the block, from the overview that gives about two cells a column (try
kunanyi or Cradle Mountain at 512 across). GEBCO fills the sea and anything off the
DEM's edge, and GEBCO 2026 alone turns it off.
Surfaces are coloured by height and latitude (sand, grass, rock, snow above a snow line that falls
toward the poles, ice past the polar circles), with dirt under the grass and stone below.
Tops can instead take Esri World Imagery: each land column's top face is the mean colour of
the imagery over its footprint, read from Web Mercator tiles at the zoom that suits; textured, the
imagery itself is laid over the tops at about 2048 pixels across the block (the .vox keeps the
mean colours).
Download .vox writes the block as a MagicaVoxel model (version 150 format: SIZE, XYZI and RGBA
chunks), the shell of each column with its sea, up to 256 voxels on a side (with Sides hidden, the
tops alone; in one colour, that colour under the tops); imagery tops go in as a
6 x 6 x 6 colour cube after the classes, the 255 colours a .vox palette allows.
Hash keys: lon, lat, ext (width in km), n
(columns across), crs (array, lonlat, laea),
vs (voxel height in m, 0 for automatic), vx, cube,
water, edges, spin, sides (layers,
colour, none), sc (side colour, hex), src (gebco,
gebco0, synth), tops (classes,
esri, esritex), cam.