extractR: Extracts pixel values from Landsat imagery

In Bartesto/BARTpkg: Utility Functions for Working with Remote Sensing Data

Description

This function must be run only after jpegR and visual QA of jpegs has been completed. It will extract either the pixel value or mean pixel values based on a point or polygon shape file respectively, from a stack of Landsat imagery. It can also extract some predefined vegetation indices (VI). This function:

1. copies individual site shape files to respective QA jpeg folders

2. obtains the dates of the remaining jpegs found in each of the QA jpeg folders

3. uses the dates obtained from step 2 to extract data (pixel values or VI) from the local USGS Landsat archive

4. writes the results of step 3 to a csv file within each QA jpeg folder

5. combines all individual site data extract csv files and writes to one csv file at the working directory level

Usage

extractR(wkdir, imdir, shp, shp.ID, option)

Arguments

wkdir	character string of the working directory where your original shape file is located
imdir	character string of the directory where imagery is located to path/row level
shp	character string of the name of the shape file (no extension)
shp.ID	character string of the name of the field in the attribute table of the shape file that contains the unique entries (e.g.site numbers)
option	character string choice for extracted values. One of "i35", "ndvi", "b1", "b2", "b3", "b4", "b5", "b6"

Value

The csv from step 5 will contain all extracted data (pixel values or VI) for each site. An 'NA' in the data indicates that a site was impacted by cloud or fell within a missing data stripe (Landsat 7 post 2003).

Author(s)

Bart Huntley, [e-mail]

Examples

## Not run: 
extractR("../wkdir", "../imdir", "plot_locations", "Plot_ID", "i35")

## End(Not run)

Bartesto/BARTpkg documentation built on May 5, 2019, 10:28 a.m.