Subsets photos whose footprint or centroid intersects the area of interest. The footprint method catches photos whose centroid falls outside the AOI but whose ground coverage overlaps it.
Usage
fly_filter(
photos_sf,
aoi_sf,
method = c("footprint", "centroid"),
buffer = 0,
dem = NULL
)Arguments
- photos_sf
An sf point object with a
scalecolumn. Geometry must be POINT — the ground footprint is estimated from a centroid, so passing footprints back in is refused rather than coerced.- aoi_sf
An sf polygon defining the area of interest.
- method
One of
"footprint"(default) or"centroid".- buffer
Buffer distance in metres added to the AOI before testing intersection (default 0). Applied in BC Albers (EPSG:3005).
- dem
Optional elevation raster passed to
fly_footprint(), sizing each frame from its height above ground instead of the reported scale. See the Terrain section offly_footprint().
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 16 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
# Footprint method finds more photos than centroid method
fp_result <- fly_filter(centroids, aoi, method = "footprint")
ct_result <- fly_filter(centroids, aoi, method = "centroid")
nrow(fp_result) >= nrow(ct_result)
#> [1] TRUE