Elevation tiles

PNG Elevation Tiles

Amazon

MapBox

Elevation Tile

Terrain Tiles on AWS

Terrain-RGB

Format

PNG (~100 KB/tile)

PNG, TIFF, HGT

Terrain-RGB

Formula to express height x

x = 2¹⁶R + 2⁸G + B

if x < 2²³, h = xu

if x = 2²³, h = NA

if x > 2²³, h = (x − 2²⁴)u

u: resolution for elevation

x = (2⁸R + G + B/2⁸) − 32,768

x = −10,000 + ((2¹⁶R + 2⁸G + B) * 0.1)

Map Projection

Web Mercator

Minimum elevation value resolution

1 m or 1/100 m

1/256 m

0.1 m

Characteristics

High versatility

Resolution and offset are fixed

Considers expressions of invalid values

Unable to represent less than −10,000 m

https://maps.gsi.go.jp/development/demtile.html

https://aws.amazon.com/jp/public-datasets/terrain/

https://www.mapbox.com/blog/terrain-rgb/