Slicing map tiles from illustrations with Rust

The goal is to recreate the functionality of tiles slicing from imagemagick in Rust. The slicing time has shown to be significantly reduced, and the built binary can be run as a platform agnostic program.

Installation for code contribution

Follow the steps from Rust Documentation

Building the project

If you are working with the code, run cargo build to create a debug build executable file in target/debug/tile-split.

If you want to generate a distributable binary, run cargo build -r to create a release build executable file in target/release/tile-split.

Running the executable

Prerequisite for Mac users: Right click ( control + click ) the tile-split program and click Open from the menu. Close the terminal and continue as normal. This step is to create an exception to Mac's security rules for running an unauthorized program.

Usage

The binary takes a single PNG file as an input, which must be a square. We tell the binary what zoomlevel the PNG file is via the --zoomlevel arg, which is compulsory. To slice a single zoom level PNG, the command is

tile-split level-5.png --zoomlevel 5

We can also optionally take a PNG for a high zoom level, downsize it to create PNGs of lower zoom levels, and then also slice those into tiles. The --zoomrange argument is used to specify which zoomlevels we want to generate tiles for. The --targetrange argument specifies subset of tiles to slice, if not provided the full range of tiles is sliced.

tile-split level-5.png --zoomlevel 5 --zoomrange 2-5 --targetrange 0-44

This would generate tiles for zoomlevels 2, 3, 4 and 5 from the single level 5 PNG and slice a subset of 45 tiles for each level.

Note that we cannot upscale an input PNG to higher zoomlevels, only downscale -- so all zoomlevels passed via --zoomrange must be equal to or less than the input PNG zoomlevel passed via --zoomlevel.

Run tile-split --help for more command description.

Split input image files into sets of tiles.

Usage: tile-split [OPTIONS] --zoomlevel <ZOOMLEVEL> <FILENAME>

Arguments:
  <FILENAME>  Input PNG filename

Options:
  -l, --zoomlevel <ZOOMLEVEL>     Zoomlevel of input PNG file [env: ZOOMLEVEL=]
  -r, --zoomrange <ZOOMRANGE>...  Zoomrange to slice tiles for
  -t, --targetrange               Targetrange to slice subset of tiles. Optional.
  -o, --output-dir <OUTPUT_DIR>   Location to write output tiles to [env: OUTPUT_DIR=] [default: out]
  -s, --tilesize <TILESIZE>       Dimension of output tiles, in pixels [default: 256]
  -f, --tileformat <TILEFORMAT>   Type of output tiles, currently unused [env: TILEFORMAT=] [default: png]
      --save-resize               Save the resized files [env: SAVE_RESIZE=]
  -h, --help                      Print help
  -V, --version                   Print version