/**
 * One-shot terrain elevation sampling (spec: "Cut/fill volume measurement").
 * Kept separate from terrain.ts, whose header documents it as PURE and
 * unit-testable without a GPU — this module is deliberately the DOM-touching
 * half (fetch + canvas), for the one thing nothing else in this codebase
 * needed before: "what is the real ground height at this lng/lat".
 *
 * Fetches the DEM tile as a blob (never an `<img src>`) so the canvas read
 * below is never tainted regardless of the provider's CORS posture — and
 * since deck.gl's own TerrainLayer already fetches this exact URL template
 * cross-origin to RENDER the surface, a caller only ever reaches this with a
 * URL that's already proven fetchable.
 */
import type { LngLat } from "./geodesy";
import type { TerrainIR } from "./terrain";
/** Slippy-map tile + fractional pixel covering `lngLat` at `zoom` (256px tiles). Exported for `terrain-heightfield.ts`'s bulk loader — same tile math, no reason to duplicate it. */
export declare function tilePixel(lngLat: LngLat, zoom: number): {
    x: number;
    y: number;
    px: number;
    py: number;
};
/**
 * Ground elevation (meters) at `lngLat`, decoded from `terrain`'s DEM at its
 * configured `maxZoom`. `null` on any fetch/decode failure — the caller
 * treats that the same as "no terrain": flat ground at 0m, not a thrown error.
 * Ignores `terrain.exaggeration` deliberately: that scales the RENDERED
 * surface for legibility, volume math wants the true decoded height.
 */
export declare function sampleTerrainElevation(lngLat: LngLat, terrain: TerrainIR): Promise<number | null>;