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Stacking, gap-filling, cloud removal of Landsat image ET Model

Source: R/rsebstack.R
sebkcstack.Rd

This function prepares landsat 5, 7, and 8 data for landsat578. First, it reads meta data and returns many input parameters for landsat578 and sebal. Second, it stacks 7 landsat layers: it stacks bands 1-7 for landsat 5 and 7; and bands 2-7,10 for landsat 8.. Third, it removes landsat clouds based on Martinuzzi et al(2009) method. Fourth, it gap-fills landsat 7 strips due to SLC-off as well as gap-filling NAs in other landsat sensors. It can also process any selected bands.

Usage

sebkcstack(
  folder,
  meta_pattern = "MTL.txt",
  remove_cloud = FALSE,
  gap_fill = FALSE,
  gap_loop = 8,
  clip = NULL
)

# Default S3 method
sebkcstack(
  folder,
  meta_pattern = "MTL.txt",
  remove_cloud = FALSE,
  gap_fill = FALSE,
  gap_loop = 8,
  clip = NULL
)

Arguments

folder

The folder or directory of landsat files

meta_pattern

The regular expression pattern to identify metadata file. The default is "MTL.txt". The function works on the new landsat metadata only.

remove_cloud

TRUE FALSE, 1, or 2. To indicate the cloud cover removal from the image. Default is FALSE. If it is set to 1, the overlapping areas of band 1 DN values between 120 and 255 and band 6 DN values of 102 to 128 are used. If it is set to 2 the union of the DN ranges are used; and clouds as well as urban, barren, quarries, rocks, and sand are removed; otherwise only clouds are removed. See Martinuzzi et al(2009) for more details. At the moment only landsat 5 and 7 clouds are removed.

gap_fill

Logical (TRUE or FALSE).It replaces strips in landsat 7 or NAs in other data set. It uses focal neighbourhood approach. It is an automated Version of USGS "Gap-Filling Landsat 7 SLC-off Single Scenes Using Erdas Imagine TM". Like USGS, it also takes approximately one hour to complete. see details at http://landsat.usgs.gov/ERDAS_Approach.php

gap_loop

numeric. The number of loops or repetitions that gap-fill should be run. The default is 8 for one landsat scene. If the landsat image is smaller, it can be reduced.

clip

extent object or raster object or polygon from which an Extent object can be extracted. A polygon or raster will be reprojected to conform the data to be cropped. for example clip can take the form of c(xmin, xmax, ymin, ymax)

Value

data:

raster stacked data. If crop is not NULL then crop Extent object is returned

brescale:

brescale of the stacked data

grescale:

grescale of the stacked data

sunelev:

sun elevation for stacked data

date:

Acquired date of the raster stacked data

viewangle:

view angle of landsat 8

azimuth:

azimuth angle of the image

sensor:

Type of satellite

K1:

K1 of landsat 8 thermal band 10

K2:

K2 of landsat 8 thermal band 10

cc:

cloud cover percentage

quality:

Image quality

row:

WRS_ROW of the image

path:

WRS_PATH of the image

Details

The function can simulate any of the activities described in the description section. It takes several minutes to replace strips (1 hour) and remove clouds (30 minutes) on one landsat scene. But stacking of bands and reading of metadata take few seconds. One can save the stacked and processed data in the same "folder" with writesebkc. The output file name is "sebkcstack.tif".

References

Martinuzzi, S., Gould, W.A., Ramos Gonzales, O.M. 2007. Creating Cloud-Free Landsat ETM+ Data Sets in Tropical Landscapes: Cloud and Cloud-Shadow Removal. USDA Forest Service General Technical Report IITF-GTR-32.

USGS Using Landsat 7 Data http://landsat.usgs.gov/ERDAS_Approach.php

Author

George Owusu

Examples

if (FALSE) { # \dontrun{
folder=system.file("extdata","stack",package="sebkc")
stack=sebkcstack(folder=folder)
#returns data and grescale
stack$data
stack$grescale
} # }