Into the Weeds of GRASS

Vaclav (Vashek) Petras

NCSU GeoForAll Lab at the Center for Geospatial Analytics
NC State University

NC GIS 2025, March 19-21, 2025

wenzeslaus.github.io/grass-talks

Vaclav (Vashek) Petras

• Sr. Research Software Engineer at NC State's Center for Geospatial Analytics
• GRASS: Core Development Team, Project Steering Committee
• OSGeo: Charter Member, GRASS is an OSGeo Project

Community

GRASS

• geospatial processing engine
• 400+ processing tools
• 400+ more tools in GRASS Addons

Releases

• 8.4.1, February 2025 Current version for everyday user
• 8.5.0 Preview, Daily Latest reviewed functional code
• 7.8.8 Legacy, August 2023 Maintained legacy version for some production systems

New in 8.4 comparing to 8.3

Tools: More Machine Learning

Supervised classification with Support Vector Machines

• i.svm.train: Train a Support Vector Machine
• i.svm.predict: Predict with a Support Vector Machine

Tools: More Topology Handling

v.fill.holes: Fill holes in areas by keeping only outer boundaries

Tools: Better Horizon Identification

r.horizon: Output for multiple points, distances, and many other improvements

Interfaces: JSON for Text Outputs

        v.db.select roadsmajor format=json
    

With better integration in Python:

        import json
        import grass.script as gs

        data = gs.parse_command("v.db.select", map="roadsmajor", format="json")
        for row in data["records"]:
            print(row["ROAD_NAME"])
    

More coming in 8.5 (r.report, r.info, …)

Locations are now Projects

The Python API, command line, and GUI are now using project instead of location for the main component of the data hierarchy.

• .../data/missouri (location → project)
  • interstate_44 (mapset aka sub-project)

Projects

• Projects keep the data consistent.
  • Same format for all data.
  • Same CRS for all data.
  • Separates data preprocessing from analysis.
• Mapsets keep the data organized.
  • One default mapset or multiple mapsets.
  • Work is happening in one mapset, but data from any mapset can be used.



        import grass.script as gs

        gs.create_project("/path/to/project", epsg="3358")
    

• .../data/missouri (project)
  • interstate_44 (mapset)
  • ...

Python API: Simpler Creation of Projects

grass.script Python package:

Greatly simplified the creation of new projects in Python without a running session (no more chicken and egg problems)

        import grass.script as gs

        gs.create_project("cordoba_utm21s", epsg="32721")
        gs.setup.init("cordoba_utm21s")
    

CLI: --tmp-project with --exec

grass --tmp-project EPSG:3358 --exec \
    r.viewshed input=elevation \
    output=viewshed coordinates=642964,222890
    

--tmp-location continues to work

Long-term view

Carrier Investment

• Invest your time into technologies which stay and don't disapear in couple years.
• Bash scripting, Python, GRASS
• Longetivity, open-source, platfrom-idependent
• Things develop, versions update, features are added...
• ...but general ideas stay the same.

Code from 2002 running in 2019?

r.mapcalc depr.bin="if((elev - fill)< 0., 1, 0)"

although there is a better way to write it:

r.mapcalc "depr_bin = if((elev - fill) < 0., 1, 0)"

Open-Source Licensing

• Organizations:
  • Provider-independent, contractor-independent.
  • Financial investments go to a public pool.
  • Pay for support and features, not usage.
  • No per-CPU license fees.
• Individuals:
  • Work computer or personal laptop.
  • Employer-independent.

More New Features 8.4

Python API: Animations and ipyleaflet

grass.jupyter Python package:

• New grass.jupyter.SeriesMap class for animating series of vectors or rasters (temporal animations already available)
• New option to create a maps with ipyleaflet (will bring interactivity in 8.5)

    s = gj.SeriesMap(height = 500)
    s.add_rasters(["elevation_shade", "geology", "soils"])
    s.add_vectors(["streams", "streets", "viewpoints"])
    s.d_barscale()
    s.show()

    m = InteractiveMap(map_backend="ipyleaflet")
    m.add_vector("streams")
    m.add_raster("elevation")
    m.show()
    

GUI: New History Browser Panel

Addon Tools: Wind-water Interactions

r.windfetch – distance which winds blow without obstruction

by Anna Petrasova, funded by NSF Award #2322073, granted to Natrx, Inc.

Addon Tools: Digest Data with EODAG

download, import, preprocessing, cloud detection, and masking of remote sensing data with EODAG (Earth Observation Data Access Gateway)

by Hamed A. Elgizery, Veronica Andreo, Stefan Blumentrath

More Features

Tools: Temporal Algebra

D = if(start_date(A) < "2005-01-01", A + B)
Sum maps from A with maps with equal time stamps from B which are temporally before Jan 1, 2005

by Thomas Leppelt and Soeren Gebbert

Tools: Skyview

by Anna Petrasova

Tools: SLIC

i.superpixels.slic - image segmentation using SLIC superpixels

by Rashad Kanavath and Markus Metz

Tools: Fast Hydrology Algorithms

by Huidae Cho

Tools: Vector Topology Cleaning

v.clean – automated topology with outputs for additional checks

by Markus Metz, Radim Blazek, and others

Tools: Urban Modeling

r.futures - set of tools for urban growth modeling

by NC State Center for Geospatial Analytics

Community and Project Maintenance

Project Roadmap

grass.osgeo.org/about/roadmap

Project Steering Committee Elections

• Elections: October 2024, Positions Filled: 4
• Total Members: 9, Term Length: 6 years

NSF Grant Lead by NC State

• NSF grant awarded to NC State, ASU, NMSU, Yale
  • To enhance infrastructure
  • To revise contributing guidelines
  • To support community building
• The NSF program is not funding new features, bug fixes, or ongoing maintenance

Financial Contributions

• Contributions through Open Collective partially support face-to-face meetings and student grants.
• We would like to finance ongoing maintenance.
• Talk to me if Open Collective does not work for you.

opencollective.com/grass

Commercial Support

New Tutorials Site

Just launched: grass-tutorials.osgeo.org

lead by the NC State Center for Geospatial Analytics

New Documentation

lead by the NC State Center for Geospatial Analytics

Swag Shop

redbubble.com/people/grassgis

or search for "grass project shop" on Redbubble

lead by the NC State Center for Geospatial Analytics

Re-adopting the Classic Name

Since GRASS is doing more in geospatial than just GIS, we are re-adopting GRASS instead of GRASS GIS.

GRASS

Lead by the NC State Center for Geospatial Analytics
& Approved by the Project Steering Committee in February

New Logo & Branding

In a testing phase and under the Project Steering Committee approval process

lead by the NC State Center for Geospatial Analytics

Mentoring and Student Grants Program

• Mentoring to integrate GRASS into your workflows (registration closes in May)
• Student grants to contribute to GRASS (call open for 2025)

Community Meeting 2024

Join a Working Group

• Groups:
  • Geoprocessing Engine
  • Open-Source Ecosystem
  • Documentation and Education
  • Community Engagement
• See wiki for details!

GRASS Developer Summit 2025

• Raleigh, NC
• May 19-24
• Register and become an insider: tinyurl.com/grass-2025
• Stay tuned for a user-focused event on Thursday, May 22

lead by the NC State Center for Geospatial Analytics

vpetras@ncsu.edu, LinkedIn: Vaclav Petras, @wenzeslaus

wenzeslaus.github.io/grass-talks