Cuaderno 3

#1. Introduccion.

En este cuaderno ilustraremos algunas funciones para obtener, procesar y visualizar Modelos Digitales de Elevación en R.

Los datos de elevación son usados en un amplio rango de aplicaciones, por ejemplo, hidrología y modelamiento ecológico.

Para obtener los datos necesarios a través de R se requería de muchos paquetes, sin embargo, esto ya no es necesario debido a que existe una variedad de API que brinda acceso a los datos de elevación.

Para acceder a los datos de elevación utilizamos el paquete “elevatr” usa Amazon Web Services Terrain Tiles.

library(rasterVis)

library(raster)

library(rgl)

library(rgdal)

library(elevatr)

#2. Conseguir dato de elevacion.

Existen varios recursos para obtener Modelos de Elevación Digital como el Shuttle Radar Topography Mission (STRM), el USGS National Elevation Dataset (NED), Global DEM (GDEM) y otros. Cada uno de esos DEMs tiene ventajas y desventajas.

Antes de su cierre en 2018, Mapzen combinó varias de estos recursos para crear un producto de elevación de síntesis que utiliza los mejores datos de elevación disponibles para una región dada a un nivel de zoom determinado. Esta compilación de datos está dispoible a través de Terrain Tiles en Amazon Web Services (AWS).

La entrada para get_elev_raster() es un data.frame con x(longitud) y y (latitud), cualquier objeto sp o raster se convierte en un RasterLayer de mosaicos que se suponerponen al cuadrado delimitador de la entrada. Si se utilizan varios mosaicos, la salida resultantes es una capa Raster combinada.

#3. Usando GET_ELEV_RASTER() para acceder a yerrain tiles en aws.

Un data.frame con columnas x y y, un objeto sp o un objeto raster necesita ser la entrada y src debe establecerse en “mapzen” (este es un valor predeterminado).

No hay diferencia en usar datos de tipo sp o raster. El data frame requiere un prj. Inicialmente, se necesita subir un shapefile que represente los municipios del departamento, en este caso, Cesar.

Ahora se procede a cargar el shapefile usando la función “shapefile” de la librería ráster

munic <- shapefile("d:/Users/Janus/Documents/Geomatica basica/18_CAQUETA/ADMINISTRATIVO/MGN_MPIO_POLITICO.shp")

Observamos los datos que contienen los archivos

head(munic)

Flor <- munic[munic$MPIO_CNMBR=="FLORENCIA"]
plot(Flor, main = "Florencia", axes= TRUE)
plot(munic, add=TRUE)

invisible(text(coordinates(munic), labels=as.character(munic$MPIO_CNMBR), cex=0.6, col = "blue"))

A continuacion descargamos los datos de elevacion de la zona de interes

elevation <- get_elev_raster(Flor, z = 8)

CRS object has comment, which is lost in outputCRS object has comment, which is lost in outputCRS object has comment, which is lost in outputDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [=>-------------------------]   7% eta: 33sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [==>------------------------]  10% eta: 25sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [===>-----------------------]  13% eta: 20sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [===>-----------------------]  17% eta: 17sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [====>----------------------]  20% eta: 15sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [=====>---------------------]  23% eta: 13sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [======>--------------------]  27% eta: 12sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [=======>-------------------]  30% eta: 11sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [========>------------------]  33% eta: 10sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [=========>-----------------]  37% eta:  9sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [==========>----------------]  40% eta:  8sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [===========>---------------]  43% eta:  8sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [============>--------------]  47% eta:  7sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [=============>-------------]  50% eta:  6sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [=============>-------------]  53% eta:  6sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [==============>------------]  57% eta:  5sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [===============>-----------]  60% eta:  5sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [================>----------]  63% eta:  4sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [=================>---------]  67% eta:  4sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [==================>--------]  70% eta:  4sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [===================>-------]  73% eta:  3sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [====================>------]  77% eta:  3sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [=====================>-----]  80% eta:  2sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [=====================>-----]  83% eta:  2sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [======================>----]  87% eta:  2sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [=======================>---]  90% eta:  1sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [========================>--]  93% eta:  1sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [=========================>-]  97% eta:  0sDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition
Downloading DEMs [===========================] 100% eta:  0s
Discarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionDiscarded ellps WGS 84 in CRS definition: +proj=merc +a=6378137 +b=6378137 +lat_ts=0 +lon_0=0 +x_0=0 +y_0=0 +k=1 +units=m +nadgrids=@null +wktext +no_defsDiscarded datum WGS_1984 in CRS definitionMerging DEMs
Reprojecting DEM to original projection
Note: Elevation units are in meters.
Note: The coordinate reference system is:
 +proj=longlat +datum=WGS84 +no_defs

elevation

class      : RasterLayer 
dimensions : 2565, 3078, 7895070  (nrow, ncol, ncell)
resolution : 0.00275, 0.00275  (x, y)
extent     : -77.3575, -68.893, -2.825057, 4.228693  (xmin, xmax, ymin, ymax)
crs        : +proj=longlat +datum=WGS84 +no_defs 
source     : memory
names      : layer 
values     : -452.4322, 5310.176  (min, max)

La salida anterior permite observar que el sistema de coordenadas de los datos es datum WGS 84. Para graficar los datos se usa la función plot

plot(elevation, main="Modelo digital de elevacion descargado (meters)")
plot(Flor, add=TRUE)

#4. Ajustar los datos a el area de estudio.

Los datos graficados anteriormente presentan un problema debido a que comprenden un área mayor a la de interes, esto se debe a la disposición espacial del arreglo de elevación en AWS.

elev_crop = crop(elevation, Flor)
plot(elev_crop, main= "Modelo de Elevacion Digital Ajustado")
plot(Flor, add=TRUE)

Visualizar las caa¿racteristicas del nuevo objeto

elev_crop

class      : RasterLayer 
dimensions : 1334, 1838, 2451892  (nrow, ncol, ncell)
resolution : 0.00275, 0.00275  (x, y)
extent     : -76.307, -71.2525, -0.7048069, 2.963693  (xmin, xmax, ymin, ymax)
crs        : +proj=longlat +datum=WGS84 +no_defs 
source     : memory
names      : layer 
values     : -245.7183, 5310.176  (min, max)

Debido al ajuste, el nuevo DEM tiene dimensiones más pequeñas que el anterior, menor cantidad de celdas pero conserva el sistema de referencias WGS 84.

#5. Reproyeccion de los datos de elevacion.

Al trabajar con DEMs resulta más conveniente utilizar coordenadas de un mapa que coordenadas geográficas. Lo anterior se debe a que en las coordenadas geográficas, las unidades horizontales son grados decimales, mientras que las verticales están en metros.

Para comenzar a reproyectar se usará MAGNA Colombia, Bogotá, por lo que se necesita definir esta referencia espacial en formato PROJ.4

spatialref <- "+proj=tmerc +lat_0=4.596200416666666 +lon_0=-74.07750791666666 +k=1 +x_0=1000000 +y_0=1000000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs"

prj <- projectExtent(elev_crop, spatialref)

Discarded datum Unknown based on GRS80 ellipsoid in CRS definition,
 but +towgs84= values preservedDiscarded datum Unknown based on GRS80 ellipsoid in CRS definition,
 but +towgs84= values preserved

Ahora es posible reproyectar los datos de elevacion del sistema de coordenadas WGS 84 a mAGNA Colombia, Bogota.

res(prj)

[1] 306.2328 304.4534

rep_elev <- projectRaster(elev_crop, prj)

(rep_Flor= spTransform(Flor,spatialref))

Discarded datum Unknown based on GRS80 ellipsoid in CRS definition,
 but +towgs84= values preserved

class       : SpatialPolygonsDataFrame 
features    : 16 
extent      : 751894.5, 1314457, 413692, 819562.9  (xmin, xmax, ymin, ymax)
crs         : +proj=tmerc +lat_0=4.59620041666667 +lon_0=-74.0775079166667 +k=1 +x_0=1000000 +y_0=1000000 +ellps=GRS80 +towgs84=0,0,0,0,0,0,0 +units=m +no_defs 
variables   : 1
names       : DPTO_CCDGO 
min values  :         18 
max values  :         18 

Graficamos

plot(rep_elev, main="Modelo de Reproyeccion elevacion dijital ")
plot(rep_Flor, add=TRUE)

#6. Estadistica basica de datos de elevacion.

Rapida exploracion estadistica para DEM

hist(rep_elev, main="Histograma de Reproyeccion", col ="blue") 

promedio <- cellStats(rep_elev, 'mean')
minimo <- cellStats(rep_elev, 'min')
maximo <- cellStats(rep_elev, 'max')
desviacion <- cellStats(rep_elev, 'sd')

Para crear un vector unidimensional

metricas <- c('mean', 'min', 'max', 'sd')
valores <- c(promedio, minimo, maximo, desviacion)

Ahora creamos un data-frame con las estadisticas de elevacion, las unidades se encuentran en metros.

(df_estadisticas <-data.frame(metricas, valores))

#7. Obtencion de variables Geomorfometricas

Primero se calcula la pendiente, aspecto y sombreado

slope = terrain(rep_elev, opt='slope', unit='degrees')
aspect = terrain(rep_elev, opt='aspect', unit='degrees')
hill = hillShade(slope, aspect, 40, 315)

plot(rep_elev, main= "DEM para Florencia (metros)", col=terrain.colors(25, alpha = 0.7))
plot(rep_Flor, add=TRUE)

Tambien es posible graficar la pendiente

plot(slope, main="Pendiente de Florencia (grados)", col=topo.colors(25, alpha = 0.7))
plot(rep_Flor, add=TRUE)

Asimismo es posible graficar eñ aspecto

plot(aspect, main="Aspecto para Florencia (grados)", col=rainbow(25, alpha = 0.7))
plot(rep_Flor, add=TRUE)

Graficamos la sombra

plot(hill, col=grey(1:100/100), legend=FALSE, main="DEM para Florencia", axes= FALSE)
plot(rep_elev, col=terrain.colors(12, alpha = 0.35), add=TRUE)

plot(rep_Flor, add=TRUE)

plot(hill,
     col=grey(1:100/100),
     legend=FALSE,
     main="DEM for Flor",
     axes=FALSE)

plot(rep_elev,
     axes=FALSE,
     col=terrain.colors(12, alpha=0.35), add=TRUE)

plot(rep_Flor, add=TRUE)

#8. Mapeando datos de elevacion con RAYSHADER.

La librería rayshader se utiliza para producir visualizaciones en 2D y 3D en R. Esta librería usa datos de elevación en una matrix R de base y una combinación de trazado de rayos, mapeo de texturas esfércias, superposiciones y oclusión ambiental para generar mapas topográficas en 2D y 3D. Además de los mapas, rayshader permite al usuario traducir objetos ggplot2 en visualizaciones en 3D.

library(rayshader)

elmat <- raster_to_matrix(rep_elev)

[1] "Dimensions of matrix are: 1838x1334."

elmat %>%
  sphere_shade(texture = 'imhof2') %>%
  plot_map()

Usamos la funcion detect_water y add_water, para representar el agua en el mapa:

elmat %>%
  sphere_shade(texture = 'desert') %>%
  add_water(detect_water(elmat), color = 'desert') %>%
  plot_map()

De igual forma, se puede agregar una capa que muestre los rayos del solsobre la superficie

elmat %>%
  sphere_shade(texture = 'desert') %>%
  add_water(detect_water(elmat), color = 'desert') %>%
  add_shadow(ray_shade(elmat), 0.5) %>%
  plot_map()

NA
NA

library(jpeg)

getv=function(i,a,s){
  ct = dim(i)[1:2]/2
  sx = values(s)/90 * ct[1]
  sy = values(s)/90 * ct[2]
  a = values(a) * 0.01745
  px = floor(ct[1] + sx * -sin(a))
  py = floor(ct[2] + sy * cos(a))
  
  
  template = brick(s,s,s)
  values(template)=NA
  
  cellr = px + py * ct[1]*2
  cellg = px + py * ct[1]*2 + (ct[1]*2*ct[2]*2)
  cellb = px + py * ct[1]*2 + 2*(ct[1]*2*ct[2]*2)
  
  template[[1]] = i[cellr]
  template[[2]] = i[cellg]
  template[[3]] = i[cellb]
  
  template = template * 256
  
  template
}

Graficamos

map=readJPEG("D:/Users/Janus/Pictures/JPEG.jpg")


out = getv(map, aspect, slope)

Discarded datum Unknown based on GRS80 ellipsoid in CRS definition,
 but +towgs84= values preservedning昼㹡n argumento finito para min; retornando Infningun argumento finito para max; retornando -Infning昼㹡n argumento finito para min; retornando Infningun argumento finito para max; retornando -Infning昼㹡n argumento finito para min; retornando Infningun argumento finito para max; retornando -Infning昼㹡n argumento finito para min; retornando Infningun argumento finito para max; retornando -Infning昼㹡n argumento finito para min; retornando Infningun argumento finito para max; retornando -Infning昼㹡n argumento finito para min; retornando Infningun argumento finito para max; retornando -Inf

plotRGB(out, main = "montañas de florencia")

Se observa que ele municipio de Florencia, presenta unicamente algunas colinas hacia el norte-occidente, lo que, teniendo en cuenta la geografia colombiana.