mlt 0.3.5

MapLibre Tile Tools
Documentation

CLI Tool

The mlt binary provides several commands for working with MLT files:

Commands

  • dump - Parse an MLT file and dump raw layer data without decoding
  • decode - Parse an MLT file, decode all layers, and dump the result (supports text and GeoJSON output)
  • hexdump - Annotated byte/bit-level hexdump of an MLT file's metadata and stream payloads
  • convert - Convert MVT or MLT tile files and MVT .mbtiles/.pmtiles archives to MLT, or tile a GeoJSON file, including 3D positions, into MLT files
  • ui - Interactive terminal visualizer for MLT files

Format conversion

Convert an MVT archive or files to MLT:

mlt convert input.mvt.pmtiles output.mlt.pmtiles

The conversion summary reports unique, decompressed tile payloads as such:

input.mvt.pmtiles -> output.mlt.pmtiles (pmtiles):
  converted 5 tiles (5 unique encoded, 0 cache hits) in 740.9ms
  size raw/archive: MVT(gzip) 813.7kB/459.8kB -> MLT(gzip) 460.3kB/357.0kB

Partial conversion

Pass --bbox min_lon,min_lat,max_lon,max_lat to convert one region of an archive, the same way martin-cp limits what it copies:

mlt convert planet.mvt.pmtiles berlin.mlt.pmtiles --bbox 13.0,52.3,13.8,52.7

Every tile overlapping the bounds is converted, at every zoom level, and the output's bounds and center metadata shrink to the region. Repeat --bbox to keep several regions. It needs an .mbtiles or .pmtiles input, the only ones that record where each tile is.

Tiling GeoJSON

Give convert a WGS84 GeoJSON FeatureCollection to tile it into a z/x/y.mlt directory as a single layer named after the file. --max-zoom is required, and --min-zoom and --layer are optional; the encoder options above apply as to any other input. This writes the v2 format, so it needs a binary built with --features unstable-v2:

mlt convert buildings.geojson tiles --max-zoom 14

Positions with an altitude ([lon, lat, alt]) become z coordinates on a --z-step grid, a power of ten in metres from -3 (1 mm) to 4 (10 km):

mlt convert power_lines.geojson tiles --max-zoom 14 --z-step -1

Visualizer

The visualizer command provides an interactive terminal-based UI for exploring MLT files:

# Visualize a single MLT file
cargo run -- ui path/to/file.mlt

# Browse and visualize all MLT files in a directory (recursive)
cargo run -- ui path/to/directory

Directory Mode:

  • Lists every .mlt, .mvt, and .pbf file under the directory; the walk and the per-file analysis run in the background, so the list fills in while you browse
  • Use ↑/↓ to navigate the file list; the preview, filter, and info panels follow the selection
  • Click a column header to sort once the scan is done; click the filter checkboxes to narrow the list
  • Press Enter to open and visualize a file
  • Press Esc to go back to file list
  • Press q to quit

Features:

  • Tree View Panel (left): Browse layers and features in a hierarchical tree
    • "All" - every layer, with layer and feature counts and the tile's geometry types
    • Individual layers - the layer's features, with each property's value types and the layer's geometry types
    • Individual features - the feature's properties and geometry statistics
    • Every panel scrolls and shows a scrollbar when its content does not fit
    • The tree also scrolls sideways with </>, Shift+Left/Shift+Right, or a sideways mouse scroll
    • Hovered rows are highlighted with underlined green text
  • Map Panel (right): Visual representation of the geometries
    • Shows the extent boundary as a thin gray rectangle
    • Draws the selected level in color and the rest in gray as context
    • Tessellation edges stored in the tile are drawn in dark gray inside the selected polygon, or inside a hovered one in a layer
    • Color coding by geometry type:
      • Points: Magenta (multipoint: light magenta)
      • LineStrings: Cyan (multi-linestring: light cyan)
      • Polygons: Blue/Red based on winding order (multi-polygon: same)
    • Polygon winding order visualization:
      • Blue: Counter-clockwise rings (typically outer rings)
      • Red: Clockwise rings (typically holes)
    • Selected features: Yellow
    • Hovered features: White
    • Automatically adjusts bounds to fit all visible geometries
  • Mouse Interaction:
    • Hovering the map targets one level below the selection, so a layer under All, a feature under a layer, a part under a feature
    • The hovered row is underlined and the info panels describe it
    • Clicking the map selects the hovered item
  • Keyboard Navigation:
    • ↑/k - Move selection up
    • ↓/j - Move selection down
    • Enter - In layer overview mode, switch to detail mode; In file browser, open selected file
    • Esc - Go back (detail -> overview -> file list) or quit if at top level
    • q - Quit the visualizer