gdalgviz

A Python library to visualise GDAL pipelines.

Installation

Requires graphviz to be installed on the system and available on the system PATH. See the installation instructions for your operating system.

GDAL itself is not required to be installed to use this library, as it only visualises the pipeline, it does not execute it.

On Linux (example installation):

apt update
apt install graphviz --yes
dot -V
apt install pipx --yes
pipx ensurepath
pipx install gdalgviz
# for Docker images
# export PATH="$HOME/.local/bin:$PATH"
gdalgviz --version
gdalgviz --pipeline "gdal vector pipeline ! read in.gpkg ! reproject --dst-crs=EPSG:32632 ! select --fields fid,geom" examples/pipeline.svg

On Windows (assuming pip and Python are on the system PATH):

$GVIZ_PATH = "C:\Program Files\Graphviz\bin"
$env:PATH = "$GVIZ_PATH;$env:PATH"
dot -V
pip install gdalgviz
gdalgviz --version
gdalgviz --pipeline "gdal vector pipeline ! read in.gpkg ! reproject --dst-crs=EPSG:32632 ! select --fields fid,geom" examples/pipeline.svg

Usage

usage: gdalgviz [-h] [--pipeline PIPELINE] [--vertical] [--font FONT] [--header-color HEADER_COLOR] [--version] [--docs-root DOCS_ROOT] [input_path] output_path

Visualize GDAL datasets from the command line

positional arguments:
  input_path            Path to a GDALG pipeline in JSON or text format
  output_path           Path to save the generated diagram (e.g., output.svg)

options:
  -h, --help            show this help message and exit
  --pipeline PIPELINE   Provide a raw GDALG pipeline string instead of a file
  --vertical            Render the diagram top-to-bottom instead of left-to-right
  --font FONT           Font name for diagram nodes (default: Helvetica)
  --header-color HEADER_COLOR
                        Background color for node headers as a hex color code (default: #cfe2ff)
  --version             show program's version number and exit
  --docs-root DOCS_ROOT
                        Root URL for GDAL documentation links(default: https://gdal.org/en/latest/programs)
  --graph-attr KEY=VALUE,...
                        Graphviz graph attributes e.g. --graph-attr bgcolor=transparent,pad=0.8
  --node-attr KEY=VALUE,...
                        Graphviz node attributes e.g. --node-attr fontsize=12,fontname=Courier

Examples

Passing a pipeline as a JSON file (tee.json):

gdalgviz ./examples/tee.json ./examples/tee.svg

Passing a pipeline as a string:

gdalgviz --pipeline "gdal vector pipeline ! read in.gpkg ! reproject --dst-crs=EPSG:32632 ! select --fields fid,geom" examples/pipeline.svg

Using the vertical layout option, with a custom font and header colour:

gdalgviz ./examples/tee.json ./examples/tee-custom.svg --vertical --font "Courier" --header-color "#ffdd99"

Using custom graph and node attributes for a transparent background with custom font sizing:

gdalgviz ./examples/tee.json ./examples/tee-transparent.svg --graph-attr "bgcolor=transparent,pad=0.5" --node-attr "fontsize=12,fontname=Courier New"

Using all options together with a complex nested pipeline:

gdalgviz \
  --pipeline "gdal raster pipeline \
    ! read n43.tif \
    ! color-map --color-map color_file.txt \
    ! tee [ write colored.tif --overwrite ] \
    ! blend --operator=hsv-value --overlay [ read n43.tif ! hillshade -z 30 ] \
    ! write colored-hillshade.tif --overwrite" \
  examples/custom.svg \
  --vertical \
  --header-color "#ffdd99" \
  --graph-attr "bgcolor=transparent,pad=0.5" \
  --node-attr "fontsize=12,fontname=Verdana"

PowerShell (Windows):

gdalgviz `
  --pipeline "gdal raster pipeline ! read n43.tif ! color-map --color-map color_file.txt ! tee [ write colored.tif --overwrite ] ! blend --operator=hsv-value --overlay [ read n43.tif ! hillshade -z 30 ] ! write colored-hillshade.tif --overwrite" `
  examples/custom.svg `
  --vertical `
  --font "Courier" `
  --header-color "#2d4a6e" `
  --graph-attr "bgcolor=transparent,pad=0.5" `
  --node-attr "fontsize=12,fontname=Verdana"

Features

• Handles both JSON and text input. See JSON Schema for the required JSON structure.
• SVG output supports clickable nodes that link to the corresponding GDAL documentation for each command. See the example.
• Supports nested pipelines. These allow sub-pipelines to be run in parallel and merged later.
• Supports tee - the operation is named "tee" because it splits the stream, like the letter "T": one input, multiple outputs, and allows saving of intermediate results.
• Supports transparent SVG backgrounds via --graph-attr "bgcolor=transparent".
• Full access to Graphviz graph and node attributes via --graph-attr and --node-attr for fine-grained control over layout, spacing, and typography.

This library does not execute the GDAL pipeline, it only visualizes it. The actual execution of the pipeline is done by GDAL itself.

To execute pipelines directly in Python you will need GDAL with Python bindings installed:

from osgeo import gdal

gdal.UseExceptions()
with gdal.alg.pipeline(pipeline="read byte.tif ! reproject --dst-crs EPSG:4326 --resampling cubic") as alg:
    ds = alg.Output()

Development

pip install -e .[dev]
black .
ruff check . --fix
# mypy .
pytest tests
gdalgviz ./examples/tee.json ./examples/tee.svg
gdalgviz --pipeline "gdal vector pipeline ! read in.gpkg ! reproject --dst-crs=EPSG:32632 ! select --fields fid,geom" ./examples/pipeline.svg

RoadMap

• Add JSON schema validation
• Add colour coding of the graph depending on if the command is raster, vector etc.
• Add types to the codebase
• Add pipeline command formatting