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fix: use proj4 +over flag to prevent antimeridian longitude wrapping #353

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fix: use proj4 +over flag to prevent antimeridian longitude wrapping #353

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22 changes: 20 additions & 2 deletions packages/deck.gl-geotiff/src/cog-layer.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -284,17 +284,35 @@ export class COGLayer<

const tms = generateTileMatrixSet(geotiff, sourceProjection);

// Use +over to disable proj4's adjust_lon longitude normalization.
// Without +over, proj4 wraps longitude at ±180° causing:
// - forward(-180.001°) → positive easting (wrong sign)
// - inverse(-WM_HALF) → +180° instead of -180°
// These 360° round-trip errors make mesh refinement (Delatin)
// unconvergeable for tiles touching the antimeridian on global COGs.
// +over is safe for longlat and Mercator targets where the 180°
// meridian projects to a straight line.
// Ref: https://proj.org/en/latest/usage/projections.html
// Ref: https://github.com/proj4js/proj4js/pull/530
// Register target projections with +over via proj4.defs so they are
// referenced by name (avoids ts-expect-error for wkt-parser input).
proj4.defs("__WGS84_OVER", "+proj=longlat +datum=WGS84 +over");
proj4.defs(
"__MERC_OVER",
"+proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +over",
);

// @ts-expect-error - proj4 typings are incomplete and don't support
// wkt-parser input
const converter4326 = proj4(sourceProjection, "EPSG:4326");
const converter4326 = proj4(sourceProjection, "__WGS84_OVER");
const forwardTo4326 = (x: number, y: number) =>
converter4326.forward<[number, number]>([x, y], false);
const inverseFrom4326 = (x: number, y: number) =>
converter4326.inverse<[number, number]>([x, y], false);

// @ts-expect-error - proj4 typings are incomplete and don't support
// wkt-parser input
const converter3857 = proj4(sourceProjection, "EPSG:3857");
const converter3857 = proj4(sourceProjection, "__MERC_OVER");
const forwardTo3857 = makeClampedForwardTo3857(
(x: number, y: number) =>
converter3857.forward<[number, number]>([x, y], false),
Expand Down