oce-class
object. Landsat data are available at several websites (e.g. [1]).
Although the various functions may work for other satellites, the
discussion here focusses on Landsat 8 and Landsat 7.This class holds satellite data of various types, including
amsr-class and g1sst-class.
x are
contained within x@data$aerosol$msb and x@data$aerosol$lsb,
each of which is a matrix of raw values. The results may be combined as e.g.
256L*as.integer(x@data[[i]]$msb) + as.integer(x@data[[i]]$lsb)
and this is what is returned by executing x[["aerosol"]].Landsat data files typically occupy approximately a
gigabyte of storage. That means that corresponding Oce objects are about
the same size, and this can pose significant problems on computers with
less than 8GB of memory. It is sensible to specify bands of interest when
reading data with read.landsat, and also to use
landsatTrim to isolate geographical regions that need
processing.
Experts may need to get direct access to the data, and this is easy because
all Landsat objects (regardless of satellite) use a similar storage form.
Band information is stored in byte form, to conserve space. Two bytes are
used for each pixel in Landsat-8 objects, with just one for other objects.
For example, if a Landsat-8 object named L contains the tirs1
band, the most- and least-significant bytes will be stored in matrices
L@data$tirs1$msb and L@data$tirs1$lsb. A similar Landsat-7
object would have the same items, but msb would be just the value
0x00.
Derived bands, which may be added to a landsat object with
landsatAdd, are not stored in byte matrices. Instead they
are stored in numerical matrices, which means that they use 4X more storage
space for Landsat-8 images, and 8X more storage space for other satellites.
A computer needs at least 8GB of RAM to work with such data.
Band 8 is panchromatic, and has the highest resolution. For convenience of
programming, read.landsat subsamples the tirs1 and
tirs2 bands to the 30m resultion of the other bands. See Reference
[3] for information about the evolution of Landsat 8 calibration
coefficients, which as of summer 2014 are still subject to change.
tirs1 and tirs2, which
are at two different gain settings, with identical wavelength span for
each, which roughly matches the range of the Landsat-8 bands tirs1
and tirs2 combined. This may seem confusing, but it lets code like
plot(im, band="tirs1") to work with both Landsat-8 and Landsat-7..------------------------------------------------------------------------------. | Band | Band | Band | Wavelength | Resolution | | No. | Contents | Name | (micrometers) | (meters) | |------+---------------------------+--------------+---------------+------------| | 1 | Blue | blue | 0.45 - 0.52 | 30 | | 2 | Green | green | 0.52 - 0.60 | 30 | | 3 | Red | red | 0.63 - 0.69 | 30 | | 4 | Near IR | nir | 0.77 - 0.90 | 30 | | 5 | SWIR | swir1 | 1.55 - 1.75 | 30 | | 6 | Thermal IR | tirs1 | 10.4 - 12.50 | 30 | | 7 | Thermal IR | tirs2 | 10.4 - 12.50 | 30 | | 8 | SWIR | swir2 | 2.09 - 2.35 | 30 | | 9 | Panchromatic | panchromatic | 0.52 - 0.90 | 15 | .------------------------------------------------------------------------------.
satellite
2. see landsat.gsfc.nasa.gov/?page_id=5377
3. see landsat.usgs.gov/calibration_notices.php
4.
5.
6. see landsat.usgs.gov/Landsat8_Using_Product.php
7. see landsathandbook.gsfc.nasa.gov/pdfs/Landsat7_Handbook.pdf
8. see landsat.usgs.gov/band_designations_landsat_satellites.php
9. Yu, X. X. Guo and Z. Wu., 2014. Land Surface Temperature Retrieval from
Landsat 8 TIRS-Comparison between Radiative Transfer Equation-Based Method,
Split Window Algorithm and Single Channel Method, Remote Sensing, 6,
9829-9652.
10. Rajeshwari, A., and N. D. Mani, 2014. Estimation of land surface
temperature of Dindigul district using Landsat 8 data. International
Journal of Research in Engineering and Technology, 3(5), 122-126.
11. Konda, M. Imasato N., Nishi, K., and T. Toda, 1994. Measurement of the Sea
Surface Emissivity. Journal of Oceanography, 50, 17:30.
amsr-class.
A file containing Landsat data may be read with read.landsat or
read.oce, and one such file is provided by the landsat.Plots may be made with plot.landsat. Since plotting can be quite
slow, decimation is available both in the plotting function and as the separate
function decimate. Images may be subsetted with
landsatTrim.
landsat-class for handling data from the Landsat-8 satellite.
Other functions dealing with satellite data: [[,landsat-method,
amsr-class, g1sst-class,
landsatAdd, landsatTrim,
plot,amsr-method,
plot,landsat-method,
plot,satellite-method,
read.amsr, read.g1sst,
read.landsat,
summary,amsr-method,
summary,landsat-method,
summary,satellite-method
Other functions dealing with satellite data: [[,landsat-method,
amsr-class, g1sst-class,
landsatAdd, landsatTrim,
plot,amsr-method,
plot,landsat-method,
plot,satellite-method,
read.amsr, read.g1sst,
read.landsat,
summary,amsr-method,
summary,landsat-method,
summary,satellite-method