Two modes: "minimal" picks the fewest photos to reach target coverage
(greedy set-cover); "all" returns every photo whose footprint intersects
the AOI.
Usage
fly_select(
photos_sf,
aoi_sf,
mode = "minimal",
target_coverage = 0.95,
component_ensure = FALSE
)Arguments
- photos_sf
An sf point object with a
scalecolumn (pre-filtered to target year/scale).- aoi_sf
An sf polygon to cover.
- mode
Either
"minimal"(fewest photos to reach target) or"all"(every photo touching the AOI).- target_coverage
Stop when this fraction is reached (default 0.95). Only used when
mode = "minimal".- component_ensure
If
TRUE(defaultFALSE), guarantee that every polygon component ofaoi_sfis covered by at least one photo before running the greedy selection. Useful for multi-polygon AOIs (e.g. patchy floodplain fragments) where small components might otherwise get zero coverage. Only used whenmode = "minimal".
Value
An sf object (subset of photos_sf). For mode = "minimal",
includes selection_order and cumulative_coverage_pct columns.
Examples
centroids <- sf::st_read(system.file("testdata/photo_centroids.gpkg", package = "fly"))
#> Reading layer `photo_centroids' from data source
#> `/home/runner/work/_temp/Library/fly/testdata/photo_centroids.gpkg'
#> using driver `GPKG'
#> Simple feature collection with 20 features and 9 fields
#> Geometry type: POINT
#> Dimension: XY
#> Bounding box: xmin: -126.7631 ymin: 54.34512 xmax: -126.449 ymax: 54.47635
#> Geodetic CRS: WGS 84
aoi <- sf::st_read(system.file("testdata/aoi.gpkg", package = "fly"))
#> Reading layer `aoi' from data source
#> `/home/runner/work/_temp/Library/fly/testdata/aoi.gpkg' using driver `GPKG'
#> Simple feature collection with 1 feature and 0 fields
#> Geometry type: MULTIPOLYGON
#> Dimension: XY
#> Bounding box: xmin: -126.75 ymin: 54.34813 xmax: -126.45 ymax: 54.47
#> Geodetic CRS: WGS 84
# Fewest photos to reach 80% coverage
fly_select(centroids, aoi, mode = "minimal", target_coverage = 0.80)
#> Spherical geometry (s2) switched off
#> Selecting photos (target: 80% coverage)...
#> 3 photos -> 81.6% coverage
#> Selected 3 of 20 photos for 81.6% coverage
#> Spherical geometry (s2) switched on
#> Simple feature collection with 3 features and 11 fields
#> Geometry type: POINT
#> Dimension: XY
#> Bounding box: xmin: -126.6796 ymin: 54.41035 xmax: -126.5269 ymax: 54.46049
#> Geodetic CRS: WGS 84
#> airp_id photo_year photo_date scale film_roll frame_number media
#> 11 697358 1968 1968-07-31 1:31680 bc5306 89 Film - BW
#> 20 697329 1968 1968-07-31 1:31680 bc5306 60 Film - BW
#> 12 697292 1968 1968-07-31 1:31680 bc5306 23 Film - BW
#> photo_tag nts_tile geom selection_order
#> 11 bc5306_089 093L07 POINT (-126.6796 54.41035) 1
#> 20 bc5306_060 093L07 POINT (-126.6039 54.42617) 2
#> 12 bc5306_023 093L07 POINT (-126.5269 54.46049) 3
#> cumulative_coverage_pct
#> 11 41.0
#> 20 66.5
#> 12 81.6
# Ensure every AOI component gets at least one photo
fly_select(centroids, aoi, mode = "minimal", target_coverage = 0.80,
component_ensure = TRUE)
#> Spherical geometry (s2) switched off
#> Seeding 9 photos for component coverage...
#> 9 seed photos -> 78% coverage
#> Selecting photos (target: 80% coverage)...
#> 10 photos -> 90.1% coverage
#> Selected 10 of 20 photos for 90.1% coverage
#> Spherical geometry (s2) switched on
#> Simple feature collection with 10 features and 11 fields
#> Geometry type: POINT
#> Dimension: XY
#> Bounding box: xmin: -126.6796 ymin: 54.34512 xmax: -126.449 ymax: 54.46049
#> Geodetic CRS: WGS 84
#> airp_id photo_year photo_date scale film_roll frame_number media
#> 18 697326 1968 1968-07-31 1:31680 bc5306 57 Film - BW
#> 11 697358 1968 1968-07-31 1:31680 bc5306 89 Film - BW
#> 13 697293 1968 1968-07-31 1:31680 bc5306 24 Film - BW
#> 10 699421 1968 1968-05-10 1:12000 bc5282 227 Film - BW
#> 4 699396 1968 1968-05-10 1:12000 bc5282 202 Film - BW
#> 17 697295 1968 1968-07-31 1:31680 bc5306 26 Film - BW
#> 15 696206 1968 1968-07-31 1:31680 bc5300 236 Film - BW
#> 12 697292 1968 1968-07-31 1:31680 bc5306 23 Film - BW
#> 6 699419 1968 1968-05-10 1:12000 bc5282 225 Film - BW
#> 20 697329 1968 1968-07-31 1:31680 bc5306 60 Film - BW
#> photo_tag nts_tile geom selection_order
#> 18 bc5306_057 093L07 POINT (-126.6025 54.34512) 1
#> 11 bc5306_089 093L07 POINT (-126.6796 54.41035) 2
#> 13 bc5306_024 093L07 POINT (-126.5269 54.43578) 3
#> 10 bc5282_227 093L07 POINT (-126.5655 54.43945) 4
#> 4 bc5282_202 093L07 POINT (-126.5869 54.45413) 5
#> 17 bc5306_026 093L07 POINT (-126.5262 54.38554) 6
#> 15 bc5300_236 093L08 POINT (-126.449 54.41519) 7
#> 12 bc5306_023 093L07 POINT (-126.5269 54.46049) 8
#> 6 bc5282_225 093L07 POINT (-126.54 54.45206) 9
#> 20 bc5306_060 093L07 POINT (-126.6039 54.42617) 10
#> cumulative_coverage_pct
#> 18 3.6
#> 11 44.6
#> 13 68.9
#> 10 70.3
#> 4 72.2
#> 17 74.8
#> 15 76.6
#> 12 78.0
#> 6 78.0
#> 20 90.1
# All photos touching the AOI
fly_select(centroids, aoi, mode = "all")
#> Spherical geometry (s2) switched off
#> although coordinates are longitude/latitude, st_union assumes that they are
#> planar
#> although coordinates are longitude/latitude, st_intersects assumes that they
#> are planar
#> Selected 20 of 20 photos intersecting the AOI
#> Spherical geometry (s2) switched on
#> Simple feature collection with 20 features and 9 fields
#> Geometry type: POINT
#> Dimension: XY
#> Bounding box: xmin: -126.7631 ymin: 54.34512 xmax: -126.449 ymax: 54.47635
#> Geodetic CRS: WGS 84
#> First 10 features:
#> airp_id photo_year photo_date scale film_roll frame_number media
#> 1 699370 1968 1968-05-10 1:12000 bc5282 176 Film - BW
#> 2 699415 1968 1968-05-10 1:12000 bc5282 221 Film - BW
#> 3 699426 1968 1968-05-10 1:12000 bc5282 232 Film - BW
#> 4 699396 1968 1968-05-10 1:12000 bc5282 202 Film - BW
#> 5 699365 1968 1968-05-10 1:12000 bc5282 171 Film - BW
#> 6 699419 1968 1968-05-10 1:12000 bc5282 225 Film - BW
#> 7 699425 1968 1968-05-10 1:12000 bc5282 231 Film - BW
#> 8 699393 1968 1968-05-10 1:12000 bc5282 199 Film - BW
#> 9 699373 1968 1968-05-10 1:12000 bc5282 179 Film - BW
#> 10 699421 1968 1968-05-10 1:12000 bc5282 227 Film - BW
#> photo_tag nts_tile geom
#> 1 bc5282_176 093L07 POINT (-126.7091 54.3727)
#> 2 bc5282_221 093L08 POINT (-126.4879 54.47635)
#> 3 bc5282_232 093L07 POINT (-126.6292 54.40794)
#> 4 bc5282_202 093L07 POINT (-126.5869 54.45413)
#> 5 bc5282_171 093L07 POINT (-126.6885 54.38426)
#> 6 bc5282_225 093L07 POINT (-126.54 54.45206)
#> 7 bc5282_231 093L07 POINT (-126.6165 54.41424)
#> 8 bc5282_199 093L07 POINT (-126.624 54.43612)
#> 9 bc5282_179 093L07 POINT (-126.7438 54.39477)
#> 10 bc5282_227 093L07 POINT (-126.5655 54.43945)