Charts checked and repaired before they are issued.
A companion for the office that already makes charts. It takes a finished set of ENC, Inland ENC or S-101 charts, finds where the skin of the world does not fit together — gaps, overlaps, edges that cross — and proposes the smallest repair that breaks nothing else. A plug-in for QGIS, the free desktop GIS.
Why it matters
Every chart describes the water as a skin: areas of known depth, areas never surveyed, and land. That skin has to fit together exactly. Where it does not, a ship's navigation system may refuse the chart, or draw it wrongly.
The postProcessor looks at a whole set before it leaves the office, so a fault is found at the desk rather than on the water.
whatItDoes
- Reviews a whole set at once, and shows every fault on the map beside
the chart.
Every fault on the map, beside the chart it is in. - Grades each fault: the simplest are repaired safely by rule, others
come with a choice of cures, and the rest are left to the cartographer's
hand.
128 charts reviewed: each finding with its level, the rule behind it and the solution on offer. - Repairs move coordinates only. Issue dates, edition numbers and the
structure of a file are never touched.
Close up: edges that cross, and the repair that separates them. 
Another crossing, close up, with its repair. - Every change is an edit to approve. Nothing is written until the
cartographer agrees, and every file written is read back to prove
it.
Every edit listed and saved before anything is written. - Changes to what a chart says — a name, a depth, a light — are made
once, in every chart the object lies in.
Every object of the set, by class; a change is made once and marked. 
One search across the whole set: by name, class or attribute. - Compares the charts with the office's own geographic services, such as a register of buoys, and suggests the updates.
- Audits a set by the IHO's own checks: S-58 for ENCs, S-158 for S-100 products.
- Converts an S-57 set to S-101 by written rules, with a report for every
dataset.
From S-57 to S-101: what changes in each chart, and the rule that says why. - Writes a delivery report: what was found, what was changed, and how long each step took.
whatItNeverDoes
- It never writes into the delivered set. The result is a new set beside
it.
The delivered set is staged and read: 128 charts, each with its issue date and edition. - It never decides alone. The cartographer carries the judgement.
- It makes no connections of its own, and sends nothing out. The office's data stays on the office's machines.
measured
On a laptop workstation, a set of 128 charts: reviewed in under nine minutes, and 873 repairs across 44 charts written in under a minute.
whereItRuns
- QGIS Version 3.34 and later, through 4.
- The workstation No server needed and no administrator rights: it installs into the user's own QGIS profile, and works on several processors side by side.
- The family It works on its own, and beside the rest of Peau du Monde.