fix: handle antimeridian-crossing tiles in Web Mercator reprojection#374
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james-willis wants to merge 1 commit intodevelopmentseed:mainfrom
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fix: handle antimeridian-crossing tiles in Web Mercator reprojection#374james-willis wants to merge 1 commit intodevelopmentseed:mainfrom
james-willis wants to merge 1 commit intodevelopmentseed:mainfrom
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Tiles near ±180° longitude cause RasterReprojector mesh refinement to diverge because forwardTo3857 maps nearby source coordinates on opposite sides of the antimeridian to EPSG:3857 x-values ~40M meters apart. Detect these tiles by checking if corner x-values in EPSG:3857 span more than half the world circumference, then wrap the projection functions to make the coordinate space continuous. Extract the wrapping logic into wrapAntimeridianProjections() in proj.ts with unit tests covering no-op passthrough, wrapping detection, coordinate continuity, and forward/inverse round-tripping. Closes developmentseed#366
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Summary
Fixes #366 — COG tiles near ±180° longitude cause
RasterReprojectormesh refinement to diverge in Web Mercator mode.Problem
When rendering an EPSG:4326 COG that spans the antimeridian,
forwardTo3857maps nearby source coordinates on opposite sides of ±180° to EPSG:3857 x-values ~40 million meters apart (+20M vs -20M). The mesh triangles connecting these vertices span the entire map, and the reprojection error never converges (currentError=43200after 10001 iterations).Solution
In
COGLayer._renderSubLayers, for the Web Mercator code path:+circumferenceso the tile's coordinate space is continuous (all positive), and unwrap in the inverse directionThis makes the mesh subdivision see a smooth, continuous coordinate space instead of a discontinuity, allowing
RasterReprojectorto converge normally.Changes
packages/deck.gl-geotiff/src/cog-layer.ts:HALF_CIRCUMFERENCEconstant_renderSubLayersTesting
pnpm build)pnpm lint)