# Extract elevation with terra

In CRAN or offline builds, network-dependent chunks are not evaluated.

This example uses BlueTopo tiles covering New York Harbor. The workflow demonstrates tile discovery, checksum-verified asset retrieval, and file-backed raster access with `terra`. Raster Attribute Table (RAT) sidecars are retained with the source GeoTIFF assets.

`bluertopo()` returns terra objects and, with `details = TRUE`, exposes selected tiles, downloads, query metadata, provenance, and coverage diagnostics. Normal native extraction does not intentionally resample.

## Example area

## Extract elevation

    result <- bluertopo(
      real_aoi,
      layers = "elevation",
      resolution = "native",
      coverage = "fill",
      details = TRUE,
      progress = FALSE,
      quiet = TRUE
    )

## Object summary

## File-backed sources

## Coverage

## Provenance

## Elevation preview

When native source grids differ, the result can be a `SpatRasterCollection`. Each member can still be file-backed by verified original assets.