Troubleshooting map2bsb: Common Errors and Fixes

map2bsb — Features & Best Practices for Nautical Chart Creation

Key features (typical for map2bsb tools)

• BSB output: Exports raster nautical charts in BSB/KAP format compatible with marine navigation software.
• Georeferencing: Reads geospatial image extents (world files, GeoTIFF tags) and embeds georeference into KAP.
• Projection handling: Supports conversion from common map projections to the Mercator variant required by many BSB users.
• Tile and strip generation: Splits large source images into KAP tiles or strips with correct overlap and offsets.
• Compression & palette control: Generates optimized indexed-color palettes and applies PNG/JPEG compression to reduce KAP size.
• Metadata embedding: Writes chart metadata (chart number, title, source, datum, publication date) into KAP headers.
• Datum & geodetic handling: Allows specifying horizontal datum and applying datum shifts for accurate positioning.
• Sea datum / depth layer support: Preserves bathymetry raster shading; can incorporate external depth/contour layers before export.
• CLI + batch processing: Command-line interface for scripting conversions of many charts.
• Preview & validation: Produces quick visual previews and validates KAP structure against reader expectations.

Best practices for creating reliable nautical charts

1. Start with high-quality source imagery — use lossless GeoTIFFs or high-resolution scans; ensure clean, straightened scans with minimal skew.
2. Confirm georeferencing accuracy — verify world files or control points; correct any misalignment before conversion.
3. Set correct datum and projection — explicitly specify datum (e.g., WGS84, NAD83) and convert to the projection expected by target ECDIS/plotter.
4. Use appropriate tiling/overlap — choose tile sizes and edge overlap that match target display software to avoid seams.
5. Optimize color palettes carefully — reduce colors to fit BSB palette limits but preserve critical navigational symbology and readability.
6. Preserve and label metadata — include chart number, edition, source, and update date in KAP headers for traceability.
7. Retain navigational features — ensure aids to navigation, depth soundings, contours, and hazards remain legible after compression/generalization.
8. Generalize for scale — simplify or omit unnecessary detail for small-scale charts; keep detail for large-scale harbor charts.
9. Validate with target software — test generated KAPs in the exact charting software or chartplotter model used operationally.
10. Automate quality checks — script checks for georeference residuals, metadata presence, and file integrity as part of batch workflows.
11. Maintain change logs and editions — track source versions and conversion parameters so updates can be regenerated reproducibly.
12. Respect licensing and source authority — only convert charts you have rights to use; label derived products clearly.

Quick workflow (example)

1. Scan or export raster as high-res GeoTIFF; ensure georeference tags present.
2. Validate/adjust georeference in GIS (QGIS, GDAL tools).
3. Reproject to required projection/datum.
4. Crop and tile for desired chart sheets.
5. Optimize palette/compression; embed metadata.
6. Export to KAP/BSB with map2bsb CLI.
7. Test in navigation software; iterate if offsets or legibility issues appear.

If you want, I can: generate a sample map2bsb command-line recipe for a GeoTIFF ➜ KAP conversion (assume GDAL + map2bsb CLI), or tailor best-practice checks to your target plotter.