jpegR: Create small jpegs of satellite imagery for analysis.

In RSPaW/RSSApkg: Utility functions for remote sensing and spatial analysis work

Description

jpegR makes small jpeg images centered on and showing site locations from a shape file. This function can be used as part of the cloud quality check process prior to extracting satellite bands or indices. Although designed to help the QA process the jpegs can be useful for quickly checking many image dates for change (e.g. fires, vegetation removal, etc) or for creating stills for animating. When run the function:

1. Obtains a list of imagery folders to access. In doing so it also checks for folder name errors (u_leapR) and only returns sun-corrected image folders.

2. Splits a supplied shape file by unique attribute field entries, stores results in a folder and writes a text file containing the original shape file name (u_shpsplitR).

3. Creates a small jpeg of the individual sites for each image date as per step 1. jpegs are based on band combination from user input and buffered by a desired distance.

4. All outputs are placed in appropriately named folders per site in the working directory

Usage

jpegR(wdir, imdir, layer, attrb, start = NA, stop = NA, combo,
  buffer = 2000)

Arguments

wdir	Character string filepath to the working directory where the original shape file is located.
imdir	Character string filepath to the path/row level for imagery.
layer	Character string of the name of the shape file (no extension).
attrb	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).
start	Character string representing start date of imagery search. Must be in the form "dmY" or "dmy" and can include separators. Defaults to NA so image search starts from first available image in the RSSA archive.
stop	Character string representing end date of imagery search. Must be in the form "dmY" or "dmy" and can include separators. Defaults to NA so image search ends with latest available image in the RSSA archive.
combo	Numerics representing bands to place in RGB channels of the jpeg. Must be of the form c(Nr, Ng, Nb) where Nr is the band number for the red channel etc.
buffer	Numeric representing how much to buffer out the site to control zoom level for jpegs. If imagery crs is projected, number represents metres. If imagery is geodetic then the number represents degrees.

Value

Creates named folders, based on site location and dates of images processed, containing small jpeg images for visual assessment.

Author(s)

Bart Huntley, [e-mail]

For more details see https://rspaw.github.io/RSSApkg/index.html the RSSApkg website

Examples

## Not run: 
jpegR(wdir = "z:/working", imdir = "W:/usgs/115078", layer = "site_locations",
attrb = "ID", start = "1/1/98", stop = "28-12-2009", combo = c(5,4,2),
buffer = 2000)

## End(Not run)

RSPaW/RSSApkg documentation built on May 21, 2019, 1:41 a.m.