Calculate focal statistics on a hyperspectral image using non-overlapping
sliding windows.
slideBrick(Brick, slide_windows, fun = median)
Arguments
| Brick |
An object of class RasterBrick or RasterStack
(from package raster), containing multiple layers (spectral bands). |
| slide_windows |
An object of class slideWindows, which consists
of a list of spatial extents giving the location of the non-overlapping
sliding windows that covers the entire image. |
| fun |
A vectorized function indicating the statistics to be calculated
within each sliding-windows, e.g. median (default), mean,
sd. |
Value
A vector or matrix containing the estimates of each sliding windows.
See also
Examples
p <- system.file('exdata', 'obory.dat', package = 'hyperbrick')
im <- buildBrick(p, ref_layer = 35,
spectral_feature = "radiance",
hFOV = 36.8, vFOV = 36.8, height = 45)
print(im)
#> class : RasterBrick
#> dimensions : 128, 128, 16384, 81 (nrow, ncol, ncell, nlayers)
#> resolution : 0.2338986, 0.2338986 (x, y)
#> extent : 512700.2, 512730.1, 5769447, 5769477 (xmin, xmax, ymin, ymax)
#> crs : +proj=utm +zone=34 +datum=WGS84 +units=m +no_defs
#> source : memory
#> names : b500, b505, b510, b515, b520, b525, b530, b535, b540, b545, b550, b555, b560, b565, b570, ...
#> min values : 0.000000, 0.000000, 3.897654, 4.049472, 4.437743, 4.817500, 4.343040, 4.413920, 4.358121, 4.428270, 4.682880, 4.520327, 4.454752, 4.520215, 4.809630, ...
#> max values : 0.00000, 0.00000, 66.79552, 67.92139, 70.52788, 71.32485, 70.51176, 68.90576, 68.98065, 70.26558, 69.09466, 69.58734, 70.76328, 73.18644, 75.02528, ...
#>
plotRGB(im, r = 63, b = 34, g = 11, scale = 90)
ext <- extent(c(512700.2, 512715, 5769462, 5769477))
sw <- slideWindows(ext, n = c(7, 7))
lapply(sw, lines, col = "white") -> null_obj
sb <- slideBrick(im, sw, fun = mean)
head(sb)
#> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
#> b500 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
#> b505 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
#> b510 12.75857 13.26442 13.17248 13.04623 12.30576 12.01026 11.88891 13.03600
#> b515 13.07932 13.53732 13.47865 13.38056 12.66994 12.40043 12.25170 13.23369
#> b520 13.87847 14.39375 14.30749 14.28247 13.46109 13.28651 13.00823 14.10483
#> b525 14.93502 15.48548 15.34373 15.23994 14.49004 14.36838 14.09447 15.09697
#> [,9] [,10] [,11] [,12] [,13] [,14] [,15] [,16]
#> b500 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
#> b505 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
#> b510 13.49851 13.60887 13.13858 13.12507 12.84848 12.42397 13.39208 13.58370
#> b515 13.81157 13.87270 13.53837 13.50300 13.17613 12.91251 13.58336 13.89090
#> b520 14.70460 14.70545 14.51737 14.34615 14.08241 13.65188 14.52388 14.67861
#> b525 15.86491 15.96884 15.63053 15.50381 15.06732 14.83548 15.62891 16.01627
#> [,17] [,18] [,19] [,20] [,21] [,22] [,23] [,24]
#> b500 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
#> b505 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
#> b510 13.82219 13.48634 13.31101 13.58479 13.67281 13.49489 13.70267 13.66638
#> b515 14.26368 13.87919 13.67203 13.97965 14.01743 13.84810 13.99755 13.95825
#> b520 15.15102 14.86996 14.60093 14.86746 14.89736 14.74459 14.93873 14.87836
#> b525 16.34274 15.94733 15.76267 16.01032 16.00211 16.02839 16.06759 16.07639
#> [,25] [,26] [,27] [,28] [,29] [,30] [,31] [,32]
#> b500 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
#> b505 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
#> b510 13.41429 13.30737 14.36494 13.99048 13.74639 13.73866 13.78157 13.81657
#> b515 13.77630 13.85798 14.75049 14.37514 14.06252 14.10911 14.20901 14.14137
#> b520 14.83823 14.66493 15.70809 15.40301 14.97668 15.05564 15.10792 15.03636
#> b525 15.89962 15.81535 17.08151 16.70013 16.30041 16.39099 16.33064 16.48963
#> [,33] [,34] [,35] [,36] [,37] [,38] [,39] [,40]
#> b500 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
#> b505 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
#> b510 13.71083 13.25106 13.57133 13.62107 14.45981 13.83782 14.08953 14.04554
#> b515 14.20134 13.74085 14.07975 13.91306 14.89052 14.14819 14.36706 14.34790
#> b520 15.07304 14.73906 14.93303 14.79873 15.74393 15.28412 15.41741 15.36628
#> b525 16.37096 16.00250 16.31982 16.16844 17.36903 16.67739 16.75917 16.83041
#> [,41] [,42] [,43] [,44] [,45] [,46] [,47] [,48]
#> b500 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
#> b505 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000 0.00000
#> b510 13.71103 13.80403 13.12301 14.42943 14.70058 14.29837 13.97457 14.49605
#> b515 14.17775 14.31161 13.46501 14.81396 14.98094 14.71744 14.44486 14.90458
#> b520 15.21705 15.26637 14.41905 15.79131 16.02945 15.76661 15.40824 15.93892
#> b525 16.54259 16.66572 15.74046 17.37034 17.53368 17.20365 16.87555 17.48165
#> [,49]
#> b500 0.00000
#> b505 0.00000
#> b510 14.39896
#> b515 15.04551
#> b520 15.98496
#> b525 17.63996