[[ operator.## S3 method for class 'landsat':
[[(x, i, j, ...)landsat-class.i item (ignored).landsat[["panchromatic"]], for the panchromatic band. If a new
``band'' is added with landsatAdd, it may be referred by
name. In all cases, a second argument can be provided, to govern
decimation. If this is missing, all the relevant data are returned. If
this is present and equal to TRUE, then the data will be
automatically decimated (subsampled) to give approximately 800 elements in
the longest side of the matrix. If this is present and numerical, then its
value governs decimation. For example,
landsat[["panchromatic",TRUE]] will auto-decimate, typically
reducing the grid width and height from 16000 to about 800. Similarly,
landsat[["panchromatic",10]] will reduce width and height to about
1600. On machines with limited RAM (e.g. under about 6GB), decimation is a
good idea in almost all processing steps. It also makes sense for
plotting, and in fact is done through the decimate argument of
plot.landsat.Accessing derived data. One may retrieve several derived quantities
that are calculated from data stored in the object:
landsat[["longitude"]] and landsat[["latitude"]] give pixel
locations. Accessing landsat[["temperature"]] creates an estimate
of ground temperature as follows (see [4]). First, the ``count value'' in
band 10, denoted $b_{10}$ say, is scaled with coefficients stored
in the image metadata using
$\lambda_L=b_{10}M_L+A_L$ where $M_L$
and $A_L$ are values stored in the metadata (e.g. the first in
landsat@metadata$header$radiance_mult_band_10) Then the result is
used, again with coefficients in the metadata, to compute Celcius
temperature $T=K_2/ln(\epsilon
K_1/\lambda_L+1)-273.15$.
The value of the emissivity $\epsilon$ is set to unity by
read.landsat, although it can be changed easily later, by
assigning a new value to landsat@metadata$emissivity. The default
emissivity value set by read.landsat is from [11], and is
within the oceanic range suggested by [5]. Adjustment is as simple as
altering landsat@metadata$emissivity. This value can be a single
number meant to apply for the whole image, or a matrix with dimensions
matching those of band 10. The matrix case is probably more useful for
images of land, where one might wish to account for the different
emissivities of soil and vegetation, etc.; for example, Table 4 of [9]
lists 0.9668 for soil and 0.9863 for vegetation, while Table 5 of [10]
lists 0.971 and 0.987 for the same quantities.
Accessing metadata. Anything in the metadata can be accessed by
name, e.g. landsat[["time"]]. Note that some items are simply
copied over from the source data file and are not altered by e.g.
decimation. An exception is the lat-lon box, which is altered by
landsatTrim.
amsr-class,
g1sst-class, landsatAdd,
landsatTrim,
plot,amsr-method,
plot,landsat-method,
plot,satellite-method,
read.amsr, read.g1sst,
read.landsat,
satellite-class,
summary,amsr-method,
summary,landsat-method,
summary,satellite-method