08-raster.Rmd

# Working with raster data {#raster}

## Prerequisites {-}

<!-- 
- nrow, ncol, nlayers, dim, ncell, res, extent, crs
- crop, mask, merge
- aggregate, disaggregate, resample
- projectRaster
- reclass, cut
- focal, focalStack, focalNA, zonal
- overlay, calc
- area, distance
- clump
- mosaic
- cellStats
- stackApply
- getValues
- terrain, hillshade ?
-->


<!-- # https://aws.amazon.com/public-data-sets/landsat/ -->
<!-- ## other stuff -->
<!-- # http://grindgis.com/blog/vegetation-indices-arcgis -->
<!-- ## calculate ndvi from red (band 1) and near-infrared (band 2) channel -->
<!-- # Band 4 reflectance= (2.0000E-05 * (“sub_tif_Band_4”)) + -0.100000 -->

<!-- process_landsat8_ndvi <- function(input, type){ -->
<!--   DN_to_radiance <- function(value){ -->
<!--     value*2.0000E-05-0.1 -->
<!--   } -->
<!--   r4 <- DN_to_radiance(input) -->
<!--   if (type == 1){ -->
<!--     ndvi <- overlay(r4[[1]], r4[[2]], fun = function(x, y) { -->
<!--       (y-x) / (y+x) -->
<!--     }) -->
<!--     writeRaster(ndvi, 'data/landsat8_ndvi_spk.tif', overwrite=TRUE) -->
<!--   } else if (type == 2){ -->
<!--     savi <- overlay(r4[[1]], r4[[2]] ,fun = function(x, y) { -->
<!--       l=0.5 -->
<!--       ((y-x) / (y+x+l)) * (1+l) -->
<!--     }) -->
<!--     writeRaster(savi, 'data/landsat8_savi_spk.tif', overwrite=TRUE) -->
<!--   } -->
<!-- } -->