https://github.com/ryodohemmi/mkgraticule_planet
Create planetary graticules for IAU coordinate systems and export them as GeoPackage (GDAL / QGIS friendly).
https://github.com/ryodohemmi/mkgraticule_planet
cartography gdal gdal-python geopackage gis iau planetary planetary-science qgis
Last synced: about 2 months ago
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Create planetary graticules for IAU coordinate systems and export them as GeoPackage (GDAL / QGIS friendly).
- Host: GitHub
- URL: https://github.com/ryodohemmi/mkgraticule_planet
- Owner: ryodohemmi
- License: mit
- Created: 2026-03-04T12:44:38.000Z (about 2 months ago)
- Default Branch: main
- Last Pushed: 2026-03-04T14:51:01.000Z (about 2 months ago)
- Last Synced: 2026-03-04T21:44:40.409Z (about 2 months ago)
- Topics: cartography, gdal, gdal-python, geopackage, gis, iau, planetary, planetary-science, qgis
- Language: Python
- Homepage:
- Size: 20.5 KB
- Stars: 0
- Watchers: 0
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
- Citation: CITATION.cff
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README
# mkgraticule_planet
[](https://doi.org/10.5281/zenodo.18864189)
Create planetary graticules for **IAU coordinate systems** and export them as **GeoPackage**.
A small CLI utility for generating latitude/longitude grids for planetary bodies using **IAU 2015 planetary coordinate systems**.
## Features
* Supports **IAU 2015 planetary coordinate systems**
* GeoPackage output
* Compatible with **GDAL 3.x**
* Multiple graticule label styles
* QGIS-friendly output suitable for map production: label fields allow immediate graticule labeling, and CRS metadata ([`definition_12_063`](https://www.geopackage.org/spec/#gpkg_spatial_ref_sys_cols_crs_wkt)) ensures that IAU coordinate systems are correctly recognized when the GeoPackage is loaded in QGIS.
* Optional major/minor classification via `-m/--major` (`grid_type = major|minor`, otherwise NULL)
* Safer handling for projected CRS with limited domains:
* abort on projected + near-global extent unless `-s/--skipfailures` is used
* optional `-p/--partial-reprojection` for partial output near projection-domain limits
* Optional dateline de-duplication for near-global longitude ranges: `-nde/--no-duplicate-endpoint`
Latitude labels:
* `lat_90` → -90° to 90°
* `lat_ns` → 90°S to 90°N
Longitude labels:
* `lon_180` → -180° to 180°
* `lon_ew` → 180°W to 180°E
* `lon_360` → 0° to 360°
* `lon_360e` → 0°E to 360°E
## Requirements
Python with GDAL Python bindings.
If you are using the OSGeo4W shell bundled with QGIS, GDAL is usually already available, so `conda install gdal` is not required.
Otherwise, one simple way to install the required GDAL Python bindings is:
```sh
conda install gdal
```
## Usage
Output filenames may be specified either with or without the `.gpkg` extension. If the extension is omitted, it is added automatically.
The `-e` option specifies the geographic extent in the order: `xmin ymax xmax ymin` (ullr style).
### Basic example
```sh
# Moon
python mkgraticule_planet.py -g 10 10 \
-r 0.2 0.2 \
-srs IAU_2015:30100 \
-e -180 90 180 -90 \
moon_graticule.gpkg
# Mars
python mkgraticule_planet.py -g 15 15 \
-r 0.5 0.5 \
-srs IAU_2015:49900 \
mars_graticule.gpkg
```
### Major/minor graticules
```sh
python mkgraticule_planet.py -g 10 10 \
-m 30 30 \
-srs IAU_2015:40100 \
-e -180 90 180 -90 \
phobos_graticule.gpkg
```
If `-m/--major` is set: `grid_type` will be `"major"` or `"minor"`.
If omitted: `grid_type` is NULL.
## Projected CRS considerations
Some projected coordinate systems (e.g., polar stereographic) have **limited valid domains**.
If a near-global geographic extent is requested, reprojection may fail.
- Default behavior: **abort** with a message suggesting to restrict the extent with `-e`
- Recommended approach: restrict the geographic extent to the valid projection domain (e.g., `-e -180 -60 180 -90` for south polar views)
- To force output anyway (skip features that fail reprojection): `-s/--skipfailures`
- Optionally enable partial reprojection: `-p/--partial-reprojection`
For projected + near-global requests, restricting the extent with `-e` is usually the best solution.
Combining `-s` with `-p` can sometimes produce partial output near projection domain limits.
### Dateline handling
If the longitude span is approximately **360°** (e.g. `-180..180` or `0..360`), duplicate endpoint meridians can be generated.
To drop the duplicate endpoint meridian while keeping the minimum longitude endpoint:
- `-180..180` → keep `-180`, drop `180`
- `0..360` → keep `0`, drop `360`
```sh
python mkgraticule_planet.py ... -nde
```
## Planetary CRS
The `-srs` option accepts any coordinate reference system supported by GDAL / PROJ.
Planetary coordinate systems typically follow the **IAU 2015 cartographic coordinate system definitions**.
Many IAU CRS definitions can be browsed at:
https://spatialreference.org/
Example codes:
- `IAU_2015:30100` — Moon
- `IAU_2015:49900` — Mars
- `IAU_2015:40100` — Phobos
## QGIS examples
### Phobos example (with major/minor classification)
Example global graticule for **Phobos**, generated using major/minor classification.
Command:
```sh
python mkgraticule_planet.py -srs IAU_2015:40100 \
-g 10 10 -m 30 30 \
phobos_grid10x10
```
### Moon south polar stereographic example
Example graticule generated for the **Moon south polar stereographic projection**
(`IAU_2015:30135`).
Because polar stereographic projections have a **limited valid domain**,
the geographic extent is restricted to the south polar region.
The `-nde` option is used to remove the duplicate endpoint meridian.
Command:
```sh
python mkgraticule_planet.py -srs IAU_2015:30135 \
-g 10 1 -m 30 2 \
-e -180 -80 180 -90 -nde \
moon_south_pole_graticule.gpkg
```
### Earth Mollweide example
Example global graticule for the **Earth** using the **World Mollweide projection**
(`ESRI:54009`).
This example shows that the tool can also be used with non-IAU coordinate reference systems supported by GDAL / PROJ.
Command:
```sh
python mkgraticule_planet.py -srs ESRI:54009 \
-g 30 10 \
-m 90 30 \
-e -180 90 180 -90 \
earth_mollweide_graticule.gpkg
```
## Output fields
| Field | Description |
| ------- | ------------------------------- |
| fid | feature id |
| lat | latitude value |
| lon | longitude value |
| lat_90 | latitude label (-90° … 90°) |
| lat_ns | latitude label (90°S … 90°N) |
| lon_180 | longitude label (-180° … 180°) |
| lon_ew | longitude label (180°W … 180°E) |
| lon_360 | longitude label (0° … 360°) |
| lon_360 | longitude label (0°E … 360°E) |
| grid_type | `"major"` / `"minor"` when `--major` is used (otherwise NULL) |
## Acknowledgement
This project is based on the GDAL sample script:
https://github.com/OSGeo/gdal/blob/master/swig/python/gdal-utils/osgeo_utils/samples/mkgraticule.py
## Citation
If you use this software in your research, please cite:
Hemmi, R. (2026). *mkgraticule_planet*. Zenodo.
https://doi.org/10.5281/zenodo.18864189
## License
MIT License. See the LICENSE file for details.