massif

Fast terrain-RGB tile generator from elevation rasters.

Converts GeoTIFF, VRT, or any GDAL-supported elevation raster into Mapbox or Terrarium terrain-RGB tiles, packaged as PMTiles or MBTiles. Ready to use with MapLibre GL for hillshading and 3D terrain.

Built as a fast Rust replacement for rio-rgbify. Uses all CPU cores via rayon, shows real-time progress, and outputs to modern tile containers — no Python overhead, no guessing when it'll finish.

Installation

Prerequisites

GDAL must be installed on your system.

Platform	Command
macOS	brew install gdal
Ubuntu / Debian	sudo apt install libgdal-dev gdal-bin
Fedora / RHEL	sudo dnf install gdal-devel
Windows	OSGeo4W or Conda — ensure gdal-config is on your PATH (untested)

Install massif

From crates.io

cargo install massif

From source

git clone https://github.com/mapriot/massif
cd massif
cargo build --release
# Binary is at target/release/massif

On macOS with Homebrew GDAL you may need:

PKG_CONFIG_PATH="/opt/homebrew/lib/pkgconfig" cargo build --release

Usage

massif [OPTIONS] <INPUT> <OUTPUT>

INPUT is any GDAL-supported elevation raster (GeoTIFF, VRT, HGT, etc., any CRS). OUTPUT is .pmtiles or .mbtiles — the container format is inferred from the extension.

Quick start

# Fastest — preview / iteration (WebP, no extra compression)
massif input.tif output.pmtiles

# Production — good balance of size and speed
massif --compress 6 input.tif output.pmtiles

# MBTiles output — same flags, different extension
massif --compress 6 input.tif output.mbtiles

# Terrarium encoding
massif --encoding terrarium --compress 6 input.tif output.pmtiles

# PNG tiles
massif --format png --compress 6 input.tif output.pmtiles

# Maximum compression for smallest files (diminishing returns past r=5)
massif --compress 6 -r 5 input.tif output.pmtiles

All options

Flag	Default	Description
--encoding	mapbox	RGB encoding: mapbox or terrarium
--format	webp	Tile image format: webp or png
--compress	(omitted)	Compression effort 1–9; omit for fastest
--min-z	5	Minimum zoom level
--max-z	12	Maximum zoom level
--nodata	(from raster)	Override nodata value (e.g. 0, -9999, -32768)
-j, --workers	all CPUs	Thread count

Mapbox encoding only:

Flag	Default	Description
-b, --base-val	-10000	Base elevation offset
-i, --interval	0.1	Elevation precision in metres
-r, --round-digits	3	Zero out lowest N bits of encoded value (reduces entropy)

Input preparation

GDAL overviews precompute downsampled versions of your raster so massif can read low-zoom tiles cheaply instead of resampling the full-resolution data each time. This reduces processing time by 20–40%.

# Single TIF — writes a sidecar .ovr file, does not modify the input
gdaladdo -ro -r average input.tif 2 4 8 16 32 64 128 256

# VRT — same approach, creates merged.vrt.ovr
gdaladdo -ro -r average merged.vrt 2 4 8 16 32 64 128 256

Massif (via GDAL) picks up the .ovr sidecar automatically. The tradeoff is storage: the .ovr file can be as large as the source data itself. If disk space is constrained, skip overviews and run without — massif handles it, just slower.

Performance

Single large TIF — 7.2 GB (Indonesia, zoom 5–12, ~142K tiles)

Machine	Version	Overviews	Command	Time	Output
Apple M4 Pro, 14 threads	v0.1.1	yes	massif	0:51	4,560 MB
Apple M4 Pro, 14 threads	v0.1.1	yes	massif --compress 6	4:52	2,844 MB
Apple M4 Pro, 14 threads	v0.1.1	no	massif	2:02	4,560 MB
Apple M4 Pro, 14 threads	v0.1.1	no	massif --compress 6	6:18	2,844 MB
Apple M4 Pro, 14 threads	v0.1.0	no	massif	2:30	4,560 MB
Apple M4 Pro, 14 threads	v0.1.0	yes	massif	1:28	4,560 MB
Apple M4 Pro, 14 threads	v0.1.0	no	massif --compress 6	6:29	2,844 MB
Apple M4 Pro, 14 threads	v0.1.0	yes	massif --compress 6	5:35	2,844 MB
Xeon Silver 4210, 20 threads	v0.1.0	no	massif	7:20	4,560 MB
Xeon Silver 4210, 20 threads	v0.1.0	yes	massif	5:42	4,560 MB
Xeon Silver 4210, 20 threads	v0.1.0	no	massif --compress 6	16:21	2,844 MB
Xeon Silver 4210, 20 threads	v0.1.0	yes	massif --compress 6	12:44	2,844 MB
Xeon Silver 4210, 20 threads	—	no	rio-rgbify	25:51	~2,810 MB

VRT of 70 TIFs — 66 GB total (Europe + Oceania, zoom 5–12)

Machine	Command	Version	Time	Output
Xeon Silver 4210, 20 threads	massif	v0.1.1	1h 36m	48,062 MB
Xeon Silver 4210, 20 threads	massif --compress 6	v0.1.1	4h 00m	29,877 MB
Xeon Silver 4210, 20 threads	massif	v0.1.0	15h 47m	48,062 MB
Xeon Silver 4210, 20 threads	rio-rgbify	-	DNF after 48h	—

rio-rgbify did not finish after 48 hours on the same machine and dataset. All massif tiles are 512×512 lossless WebP images. The Xeon results were measured on a server under normal production load — actual times on an idle machine would be lower.

Setting	Impact	Notes
EPSG:4326 input	~2.5× faster (no compress)	massif skips GDAL transforms entirely; use gdalwarp -t_srs EPSG:4326
GDAL overviews	−20–40% time	Effective for single TIFs; .ovr can match source file size
WebP vs PNG	WebP is 2× smaller	Use PNG only if client doesn't support WebP
--compress 6	−38% size vs no compression	Best size/speed tradeoff; gains flatten past 5
-r 3 (default)	−43% size vs r=0	Biggest lever for file size; invisible for hillshading at most latitudes
Terrarium vs Mapbox	Terrarium is 3.1× larger	No round-digits equivalent; use Mapbox when possible

For full benchmark methodology, all 36 parameter combinations, and recommended settings by use case, see docs/benchmarks.md.

Encoding schemes

Mapbox (default)

encoded = floor((elevation - base_val) / interval)
R = (encoded >> 16) & 0xFF
G = (encoded >> 8)  & 0xFF
B =  encoded        & 0xFF

MapLibre decodes as:

height = base_val + (R × 65536 + G × 256 + B) × interval

With the defaults (-b -10000 -i 0.1), the encodable range is −10,000 m to +1,677,721.5 m at 0.1 m precision. The -r flag zeroes the lowest N bits of the encoded integer — this reduces entropy for better compression with negligible quality loss for hillshading. Note: -r 3 may produce visible artifacts at high latitudes (e.g. northern Norway, Svalbard, Greenland) where elevation gradients are subtle; use -r 1 or -r 0 for polar regions.

Terrarium

val = elevation + 32768
R = floor(val / 256)
G = floor(val) mod 256
B = floor(frac(val) × 256)

MapLibre decodes as:

height = (R × 256 + G + B / 256) − 32768

Range: −32,768 m to +32,767.996 m at ~0.004 m precision. Used by Mapzen and many open elevation datasets. No configurable parameters — -b, -i, and -r are ignored with a warning.

Using with MapLibre GL

{
  "sources": {
    "terrain": {
      "type": "raster-dem",
      "url": "pmtiles://https://example.com/terrain.pmtiles",
      "encoding": "mapbox",
      "tileSize": 512
    }
  },
  "terrain": {
    "source": "terrain",
    "exaggeration": 1.5
  },
  "layers": [
    {
      "id": "hillshading",
      "type": "hillshade",
      "source": "terrain"
    }
  ]
}

For Terrarium output, set "encoding": "terrarium" in the source.

Input formats

Any raster supported by GDAL — GeoTIFF (.tif), Virtual Raster (.vrt), HGT, IMG, and more. Any pixel data type works (Float32, Float64, Int16, UInt16, etc.) — GDAL converts to Float32 internally. The input can be in any CRS; massif reprojects each tile to Web Mercator on the fly.

Common elevation data sources:

• ALOS World 3D
• SRTM
• Copernicus DEM (GLO-30, GLO-90)

License

MIT — see LICENSE