S-411 sea-ice preview generator (sample)

This sample is a Bash script that makes PNG previews of S-411 sea-ice data with s100 render. It works like the previews on the BSIS Ice Portal: it downloads each region's published S-411 exchange set, extracts the GML dataset and renders it. Use it as an example of running s100 in an unattended batch job.

The portal's file names include a date and change, often daily. The script finds the current file for each region by matching a fixed pattern against the live portal index, so you don't need to update it as new files are published.

Prerequisites

The .NET 10 SDK.
bash, curl and unzip.

A Release build of s100. From the repository root:

dotnet build tools/EncDotNet.S100.Cli -c Release

Run the script

You can run the script from any folder in the repository. With no arguments, it renders the cw-greenland, hudson-bay and alaska regions into ./s411-previews:

samples/s411-previews/s411_previews.sh

Pass an output folder, then one or more region keys, or all:

samples/s411-previews/s411_previews.sh /tmp/out north-atlantic hudson-bay
samples/s411-previews/s411_previews.sh /tmp/out all

For each region, the script prints the file it found and the preview it wrote. It skips a region whose file it can't find, download or render, and goes on to the next.

Regions

Source	Region keys
DMI (Greenland)	`cw-greenland`, `nw-greenland`, `ne-greenland`, `se-greenland`, `sw-greenland`, `ce-greenland`, `cape-farewell`, `qaanaaq`
CIS (Canada)	`canada-east`, `hudson-bay`, `eastern-arctic`, `western-arctic`
US NWS	`alaska`
Met.no	`north-atlantic`

To add a region, add entries to the region_zip_pattern, region_conc_image and region_sod_image functions in the script, using the file names on the BSIS portal. If a region stops resolving, its file-name pattern has probably changed; update its region_zip_pattern entry from the portal index.

Settings

Set these environment variables to change how the script renders:

Variable	Default	Description
`S100`	`dotnet` with the Release `s100.dll`	The command that runs `s100`, such as the path to a downloaded `s100` binary.
`WIDTH`, `HEIGHT`	`1600`	The image size in pixels.
`PALETTE`	`day`	`day`, `dusk` or `night`.
`EXTRA_OPTS`	empty	More options for `s100 render`, added after `--width`, `--height` and `--palette`.
`COMPARE`	`0`	`1` also downloads the BSIS previews for comparison. See Compare with the BSIS previews.

For example, to use a downloaded s100 and a larger image in the night palette:

S100="path/to/s100" WIDTH=2048 HEIGHT=2048 PALETTE=night \
  samples/s411-previews/s411_previews.sh

Output

<out-dir>/
  data/ILP_S411.shtml               the cached portal index
  data/<region>.zip                 the downloaded exchange set
  data/<region>/...                 the extracted exchange set
  previews/<region>.png             the rendered preview
  previews/<region>.bsis-conc.png   the BSIS concentration preview (COMPARE=1)
  previews/<region>.bsis-sod.png    the BSIS stage-of-development preview (COMPARE=1)
  previews/<region>.compare.png     a side-by-side sheet (COMPARE=1, with montage)

The output isn't meant to be committed.

Change the preview

Pass s100 render options through EXTRA_OPTS:

Hide the labels. --no-text removes the S-411 egg-code labels and leaves the fills, ice-edge lines and symbols, like the BSIS previews. --hide text,points also removes point symbols.
```
EXTRA_OPTS="--no-text" samples/s411-previews/s411_previews.sh
```
Add land. --basemap offline draws the bundled Natural Earth 1:10m land layer under the ice, so you can see the coastline. It doesn't use online tiles.
```
EXTRA_OPTS="--no-text --basemap offline" samples/s411-previews/s411_previews.sh
```
Show the stage of development. The default display mode shows total concentration. --display-mode ice-sod shows the stage of development instead.
```
EXTRA_OPTS="--display-mode ice-sod" samples/s411-previews/s411_previews.sh
```

For every render option, see Command-line rendering.

Compare with the BSIS previews

With COMPARE=1, the script also downloads the BSIS concentration preview and, where the portal publishes one, the stage-of-development preview, for each region. If ImageMagick's montage is on your PATH, it also puts your render and the BSIS previews side by side in previews/<region>.compare.png.

COMPARE=1 samples/s411-previews/s411_previews.sh /tmp/out cw-greenland

The comparison shows that s100 render reproduces the S-411 data: the ice-edge polygons, fjord tongues and offshore patches line up with the BSIS concentration preview. The differences come from how the image is composed. s100 render draws the chart layer with the S-411 portrayal; the BSIS previews are complete figures made by a separate script.

Aspect	BSIS preview	`s100 render`
Background	Blue ocean, white land, a latitude and longitude grid, a title and axes	No background map by default. `--basemap offline` adds land; there's no ocean colour, grid, title or axes.
Concentration colours	A WMO colour ramp, green to red from low to high	WMO total-concentration colours, in the default `ice-concentration` mode.
Stage of development	A separate map	A separate render with `--display-mode ice-sod`.
Projection	Equirectangular	Web Mercator.
Extent	A fixed frame for each region, including the nearby coast	Fitted to the data. Use `--bbox` for a fixed frame.

Most BSIS region pages also publish POLARIS navigational-risk maps, one for each ice class, coloured by risk index outcome. These are calculated decision-support products, not a portrayal of the data, and EncDotNet.S100 has no POLARIS calculation. The ice-navigational display mode is a provisional preview derived from total concentration, not a POLARIS result. COMPARE mode downloads only the concentration and stage-of-development previews.

Data and terms of use

The S-411 data comes from the ice services (CIS, DMI, Met.no, US NWS/NIC, AARI, SHN and others) through the BSIS Ice Portal. Follow their terms of use.

This is sample code, not a supported product.