# Example data

## Bird trajectory

An example GPS track of a stork `niclas` and an example Digital Elevation Model `dem` are included in the package. The DEM is a snippet from the SRTM 90m Digital Elevation Database v4.1 from CGIAR-CSI and the stork track is a subset of the data in the study LifeTrack White Stork SWGermany 2014-2017 (Movebank Study ID 21231406) from the Movebank Data Repository.

The area covered by the test data is the Swiss midland. The example track is a data.frame with coordinates in x, y and z. The x and y coordinates are in the CH1903+ / LV95 (EPSG:2056) reference system.

    head(niclas)
    #>         x       y        z
    #> 1 2556476 1188336 1283.736
    #> 2 2558565 1189297 1359.580
    #> 3 2560477 1189861 1369.713
    #> 4 2562431 1190668 1391.752
    #> 5 2563809 1190657 1806.566
    #> 6 2567940 1192930 1764.062

## Digital elevation model

The DEM is a rasterLayer of the raster package, it’s Coordinate Reference System (CRS) is also CH1903+ / LV95. The stork flies from southwest to northeast, GPS fixes are collected every 15 minutes.

    dem
    #> class      : RasterLayer
    #> dimensions : 175, 501, 87675  (nrow, ncol, ncell)
    #> resolution : 251.2, 370.8  (x, y)
    #> extent     : 2543252, 2669103, 1177108, 1241998  (xmin, xmax, ymin, ymax)
    #> crs        : +init=epsg:2056 +proj=somerc +lat_0=46.95240555555556 +lon_0=7.439583333333333 +k_0=1 +x_0=2600000 +y_0=1200000 +ellps=bessel +towgs84=674.374,15.056,405.346,0,0,0,0 +units=m +no_defs
    #> source     : memory
    #> names      : srtm_38_03
    #> values     : 374.3316, 2602.137  (min, max)