BlueTopo tile metadata records each source tile’s native cell size.
Smaller meter values mean finer source detail. In
bluertopo, resolution chooses which source
tiles to use; output_resolution creates a new output grid
and therefore resamples.
Shortcuts
# Use every intersecting native source resolution.
bluertopo(aoi, resolution = "native")
# Prefer the finest available native source tiles.
bluertopo(aoi, resolution = "finest")
# Prefer the coarsest available native source tiles.
bluertopo(aoi, resolution = "coarsest")
# Keep all available resolutions as candidates.
bluertopo(aoi, resolution = "best_available")Exact and nearest values
Numeric resolution values request exact native meter
values. Use bluertopo_resolution() for explicit
nearest-neighbor behavior.
bluertopo(aoi, resolution = 8)
bluertopo(
aoi,
resolution = bluertopo_resolution(
"nearest",
value = 10,
tie = "finer"
)
)Ranges and ranks
bluertopo(
aoi,
resolution = bluertopo_resolution("between", min_m = 4, max_m = 16)
)
bluertopo(
aoi,
resolution = bluertopo_resolution("finest_n", n = 2)
)n must be a positive whole number. Fractional values are
rejected rather than silently truncated.
Coverage-oriented selection
Coverage diagnostics compare selected tile coverage against all
published tile coverage intersecting the AOI.
coverage = "fill" adds fallback native resolutions until
the target is met or no fallback remains.
bluertopo(
aoi,
resolution = "finest",
coverage = "fill",
min_coverage = 0.95
)
policy <- bluertopo_resolution(
"coverage",
prefer = "finest",
min_coverage = 0.90
)
bluertopo(aoi, resolution = policy, coverage = "fill")For strategy = "coverage", the coverage target stored in
the resolution policy is used. For other strategies, the function-level
min_coverage argument is used.