Data interoperability

OTKGlobeEngine reads and writes data through a registry of format adapters (otk/formats.hpp). Each adapter declares what it is, which extensions it uses, whether it imports and exports, and whether it needs the optional GDAL module. Imported content becomes engine Features, independent of rendering, so it can be stored, queried, transformed, rendered and exported without re-parsing.

otk::ImportResult in = otk::importData("mission.zip");          // format detected from content
otk::ExportResult out = otk::exportFeatures(in.data.features, "mission.kml");
for (const auto& note : out.lossy) puts(note.c_str());           // explicit list of what the target cannot hold

Engine::loadFeatures uses the same path, so every vector format below loads with one call, and Engine::exportFeatures writes any of the exporters. The C ABI exposes otk_export_features, otk_detect_format and otk_formats_markdown.

Detection

Formats are detected from content first and extension second: zip archives are told apart by their entries (TAK MANIFEST/manifest.xml, KMZ doc.kml, ATAK iconsets iconset.xml), XML by its root element (kml, event/events, gpx, GML feature collections, MOBAC map and WMS sources), JSON by its members (GeoJSON, 3D Tiles tileset.json, TileJSON, Cesium terrain layer.json), and binaries by magic numbers (SQLite, PMTiles, LAS, glTF, b3dm, TIFF, Shapefile, DTED). SQLite tile stores are told apart by extension and schema (MBTiles, GeoPackage, osmdroid, RMaps/BigPlanet, OsmAnd). CSV and WKT are recognised from their first lines.

Tile sources

• URL templates accept {z}, {x}, {y}, {-y}, {s}, {r}, {quadkey}, {reverseX}, {reverseY}, {reverseZ}, {westDegrees}, {southDegrees}, {eastDegrees}, {northDegrees} (and the Projected variants), {width}, {height}, {bbox-epsg-3857} and {bbox-epsg-4326}, so Cesium, MapLibre and Leaflet templates work unchanged.
• ImageryLayer::headers and ElevationLayer::headers add request headers (API keys, Authorization, Referer) to every tile and metadata request.
• Cesium terrain loads from a layer.json URL, a local terrain folder or layer.json path (for example cesium-terrain-builder output, gzipped or not), a {z}/{x}/{y}.terrain template or ion://<asset id>?access_token=<token> (add &server=<url> for a self-hosted ion server). quantized-mesh-1.0 and heightmap-1.0 tiles are both read, the available ranges limit requests to tiles that exist, and ion tokens are refreshed when they expire.

KML

• NetworkLink documents are fetched from local paths, KMZ entries or HTTP(S). viewRefreshMode onStop and onRegion links get the current view as a BBOX (or their own viewFormat), and httpQuery is appended. A file loads at most 64 links, nested at most four deep.
• Model placemarks load COLLADA (.dae), OBJ or binary glTF (.glb) models from the KMZ or beside the file, with Location, Orientation, Scale and altitudeMode.
• extrude draws walls under lines and polygons and stalks under points when they are not clamped to the ground.
• Icon and Model hrefs may be HTTP(S) URLs.

CoT and ATAK

• ATAK iconset zips are registered with registerIconset (C ABI otk_register_iconset), and usericon iconsetpath markers draw the matching icon.
• Range and bearing lines (u-rb-a) are drawn from their range and bearing.
• strokeStyle dashed and dotted, color (argb or value), strokeColor, strokeWeight and fillColor are honoured.

Metadata preservation

• Every feature carries a stable uid, a CoT type, ordered string attributes, and time, start and stale (UTC seconds).
• KML: Placemark id, ExtendedData (Data and SchemaData), TimeStamp, TimeSpan, styles, altitude mode.
• GeoJSON: id, every property (non-string values kept as JSON text), simplestyle colours.
• GPX: name, description, type, symbol, comment, waypoint time, track start and end.
• Shapefile: every DBF field. Coordinates are reprojected to WGS84 from the .prj: geographic, Transverse Mercator (UTM, Gauss-Kruger), Lambert conformal conic (1SP and 2SP, State Plane), Albers equal area, Mercator and Web Mercator are handled natively in metres, feet or US survey feet; other projections go through GDAL when it is available.
• CoT: uid, type, how, time/start/stale, ce/le, callsign, remarks, colours, drawn shapes, and the raw <detail> block, which is written back unchanged so CoT round-trips are lossless. Non-CoT attributes ride in a private <__otk_attributes> element that TAK clients ignore.
• CSV: all columns that are not coordinates, name, description, uid, type or time become attributes.
• GML: feature gml:id, simple property elements, WGS84 geometry with the correct EPSG:4326 axis order.

Round trips through GeoJSON, KML, GML, CSV, CoT and TAK data packages are covered by otk_unit and keep uid, type, attributes, times and polygon holes. Exports report every loss in ExportResult::lossy (for example GPX has no polygons or attributes, WKT keeps geometry only).

Untrusted input

• Files over 1 GiB, archives over 2 GiB uncompressed or 20,000 entries, and archive nesting deeper than three levels are refused (ImportLimits).
• Archive entries with absolute paths, drive letters or .. are skipped.
• XML is parsed without DTD processing, so external entities are never fetched.
• Feature counts are capped at five million per import.
• KML network links are capped at 64 per file, four levels of nesting and 64 MiB per download; KML models at 256 per file; converted models at 20 million vertices.

Compatibility matrix

"Needs GDAL" formats are available when the engine is built with -DOTK_WITH_GDAL=ON (the Linux CI build does); availability then depends on the drivers compiled into that GDAL. At runtime formats() and formatsMarkdown() report the formats present in the running build.

Military and government formats

• NITF, CADRG/CIB (RPF A.TOC), DTED, ADRG and S-57 load through GDAL's drivers; DTED and SRTM HGT also have native readers.
• MIL-STD-2525 C/D symbology is rendering, not a data format: CoT type strings and SIDCs are drawn as 2525 icons by otk/milsym.hpp.
• VMAP/VPF has no GDAL driver; it needs OGDI and is not supported.
• Formats without public specifications or with export-controlled specifications are out of scope unless a licensed implementation is supplied.

Licensing

Linked libraries and their licenses are listed in THIRD_PARTY.md. LAZ would need LASzip (LGPL) as an optional module; ECW and MrSID need their vendors' SDKs through GDAL. No ATAK (GPLv3) code is used.

Planned adapters

LAZ point clouds and a CoT network adapter (TCP/UDP/TLS to TAK Server and mesh SA). CoT messages from any transport already parse with the cot adapter.