Import/Catalogue/IWAI CSIG

Goals

The aim is to import the Shannon/Erne inland waterways navigation dataset, sourced from IWAI (Inland Waterways of Ireland) CSIG (Charts Special Interest Group).

Schedule

n/a

Import Data

Background

Data source site: https://chartssig.iwai.ie/
Data license: n/a
Link to permission (if required): Granted to use this data to update OpenStreetMap via email conversation.
ODbL Compliance verified: yes

OSM Data Files

The prepared OSM data file is available on via Dropbox

Import Type

This is a one-time import as the vast majority of the navigation marks are static. The initial preparation will be done using automated scripts, and conflation resolution will be done manually. Data will be imported into the OSM database using JOSM.

Data Preparation

Data Reduction & Simplification

The data initialy came in a set of CSV files, one for each class of navigation mark, located using ITM grid references, in addition to a LABEL field. No reduction or simplification is required.

Tagging Plans

• All marks have a iwai_csig:type=* custom tag added to identify the original source
• Lough Erne navigation marks also have a proposed lough_erne_nav:type=* tag
• Lateral navigation are encoded using:
  • seamark:type=beacon_lateral for "posts"
  • seamark:type=buoy_lateral for major and minor marks
  • Topmarks are added, green square for Starboard, and red sphere for Port
• Stone cairns are encoded using the seamark:type=beacon_special_purpose scheme
• End of Navigation (EON) are tagged as a CEVNI closed area (prohibition) seamark:type=notice mark

Changeset Tags

• source=IWAI CSIG
• source:date=2023-09-04

Data Transformation

1. Combine CSV using a Bash shell script
2. Load into QGIS, and re-export as a GeoJSON file using the EPSG 4326 projection
3. Transform to OSM using a Node JS script

Data Transformation Results

The prepared OSM data file is available on via Dropbox

The locally rendered tiles are available for visualising. The modified area spans from 12/1949/1340 to 12/1955/1305.

Data Transformation Issues

• End of Naviation marks on the Shannon do not conform to either INT Section Q or CEVNI notice marks. This was worked around by using the CEVNI scheme.
• Lough Erne uses [fairly] unique navigation marks, which will cause some issues:
  1. They do not conform to IALA:
     • they are a red-white vertical pattern, with the white side indicating the side that should be passed, and red the "hazard" side
     • the topmark is a hemisphere, which is not available as a shape
  2. They are directional, eg. from one direction the mark will be red-white, where as from the opposide direction the mark will be white-red. This makes it difficult to render on a chart in the usual manner. The [The Erne Waterway Chart](https://www.manormarine.com/site/wp-content/uploads/2016/07/ErneWaterwayChart.pdf) depicts them in a fashion that is not possible currently possible on OpenSeaMap
  3. The solution is to to encode them using:
     • seamark:topmark:shape=circle
     • seamark:topmark:colour_pattern=vertical (or vertical, depending on the hazard direction)
     • seamark:topmark:colour=red;white (or white;red, depending on the hazard direction)

Data Merge Workflow

Team Approach

This is a sole task.

References

Local knowledge, Bing aerial photography.

Workflow

1. Download an extract of all {Tagg|seamark:type}} nodes from OverPass
2. Load both the OverPass extract and the generated OSM files into JSOM
3. Start from the Southern part of the dataset at Limerick, and work northward along the Shannon
4. Visually compare the two layers, and copy the generated tags into the extract (see Conflation)
5. For Lough Erne laternal markers, the direction of the hazard was determined from OSM data and Bing aerial photography

Conflation

• Prefer description and naming provided by the CSIG
• If the distance between nodes is mininal, prefer the location provided by the CSIG
• If the distance is large, attempt to use references to identify the likely location - in many instances navigation marks are visible in aerial photography

QA

1. Validate the data using JOSM Tagging Validator
2. Verify rendering of marks using jrender to render tiles locally

Acknowledgments

I'd like to thank the IWAI CSIG and Brian Wilson for allowing me to use the data that their members and contributors have collected.