Python machine learning to classify forest/trees (vegetation) in multispectral, panchromatic satellite imagery.
Python
GENERAL DESCRIPTION: VEGETATION AND FOREST CLASSIFICATION WITH MACHINE LEARNING AND PYTHON
Satellite imagery products often come with several multispectral bands: Red, Green, Blue, NIR, and
sometimes, a high-resolution panchromatic band. Some of these products may come from satellites (orbiters) including
the Landsat (i.e. NASA's Landsat 8, launched in 2013), as well as Sentinel II (ESA's Copernicus
program).
This program is meant to be called on the UNIX-like command-line, in which the user must
pass-in 1-band (1 image layer or array) georeferenced image filenames (i.e. Geotiffs or JPEG2000,
PNG with "world file," etc.), including those for the Red, Green, Blue, and NIR bands. These are
required. The user must also pass-in two filename(s) for two shapefiles. One of these shapefiles
will hold points marking trees/forest/vegetation, and the other holidng points for
non-trees/non-vegetation/non-forest. Finally, the user must also pass-in the number of "trees"
(integer) for the number of "trees" used in Python/Sklearn's ExtraTreesClassifier() method
(usually between 1 and 15). Optionally, this program allows the user to pass-in a NOData (nan)
value (usually -9999 or 0) at the command line, as well as a desired output directory.
This program will do the following:
(1) Computes a panchromatic image Geotiff if necessary (if user did not pass this at command-line)
using the formula (Red+Green+Blue+NIR)/4.0.
(2) Resamples the panchromatic band (usually by downsampling using nearest-neighbor), if necessary,
(i.e. if it was passed at the command-line) to the same resolution and dimensions as the input
multispectral RGB,NIR imagery.
(3) Computes a supporting set of georeferenced (GDAL) raster satellite imagery files, including
Normalized Difference Vegetation Index (NDVI), Soil-Adjusted NDVI (SAVI) for L = 0.1,0.2,...1.0
(see https://wiki.landscapetoolbox.org/doku.php/remote_sensing_methods:soil-adjusted_vegetation_index),
as well as "background" imagery (Gaussian-filtered) for the Red,Green,Blue,NIR,Panchromatic, and
NDVI band and/or band combinations. Also creates an RGB Geotiff mosaic.
(4) Reads both vegetation and non-vegetation POINT shapefiles and converts these latitude/longitude
projected points into Row/Column space for the input NIR/RGB imagery passed-in. Gathers corresponding
pixel values from all imagery (RGB,NIR,Panchromatic, "Backround" imagery, NDVI, SAVI) and writes all
pixel values to a CSV file. Values of 1 mark "trees/vegetation" and 0s mark "non-trees/non-vegetation"
in the right-most column of this CSV ("Label"). Each row in this CSV represents one POINT from one
of the TWO shapefile(s) passed-in at command-line. This CSV hence contains "Training Data"
used for vegetation classification.
(5) Uses CSV from (5), as well as Python machine-learning tools from Sklearn and Pandas, to
write a PNG and Geotiff containing a final forest (woods/trees) classification for the
imagery set. 1s are forest (vegetation), 0s are non-forest (i.e. not vegetation).
For increased accuracy, ensure both input shapefile(s) have more points (i.e. training data).
PYTHON VERSION
Supports Python 2.7.x. May run with Python 3.x with minor modifications.
FURTHER EXPLANATION OF METHODOLOGY
See see a simplifed version of this code, visit this site:
https://gerasimosmichalitsianos.wordpress.com/2019/05/26/classification-of-forest-vegetation-in-satellite-imagery-using-machine-learning-and-python/
This example blog entry shows how the code works, assuming all "training imagery" (NDVI,SAVI,...)
has already been created, along with the CSV containing the "training data" of
all relevant pixel values and tree/non-tree label (1 or 0 in the final "Label" column).
INSTALLATION
git clone https://github.com/gerasimosmichalitsianos/VegetationClassification
pip install VegetationClassification/
or to upgrade:
pip install VegetationClassification/ --upgrade
This will create a new command-line tool called "VegetationClassification"
(i.e. /home/username/.local/bin/VegetationClassification)
USAGE MESSAGE
NAME:
VegetationClassification{.py}
DESCRIPTION
It is common for satellite imagery to include bands for the Red, Green, Blue,
and Near-Infrared (NIR) bands, among others. Each of these would correspond to
a frequency and/or reflectance (or irradiance) channel for a particular satellite
(i.e. Landsat, MODIS, Sentinel, and so on). These bands can be used to compute
various combinations that would help to classify vegetation in the satellite
imagery (i.e. Normalized Difference Vegetation Index, NDVI).
This command-line program uses Python and machine-learning to classify a set of
satellite imagery into a vegetation and non-vegetation. To this end, this program
computes various parameters, Normalized Difference Vegetation Index (NDVI), SAVI
(Soil-Adjusted NDVI) for 10 different thresholds, as well as a Panchromaic image
(if needed). The final output is a Geotiff with 1s and 0s, whereas 1s mark
trees/woods and 0s mark non-trees (non-forest/woods).
USAGE:
To use this program, run it at command-line with the
following possible arguments:
$ VegetationClassification
Command-Line Options:
{ --help, --h, -h }
Display this help usage message
{ --outdir, -o }
Output directory path (optional)
{ --ntrees, --numtrees, --numbertrees }
Number of trees used in ExtraTreesClassifier (optional, default is 3)
{ --panchromatic, -p }
Panchromatic Image Filename (optional)
{ --red, -r }
Image Filename for "Red" Band or Channel (required)
{ --green, -g }
Image Filename for "Green" Band or Channel (required)
{ --blue, -b }
Image filename for "Blue" Band or Channel (required)
{ --nir, -n }
Image Filename for "NIR" or Near-Infrared Band or Channel (required)
{ -z, --background, --nontrees, --nonvegetation }
Shapefile (.shp extension) for points marking NOT trees/vegetation (required)
{ -t, --targets, --trees, --vegetation }
Shapefile (.shp extension) for points marking trees/vegetation (woods) (required)
{ -i, --ignore, --nodata }
Imagery pixel value to ignore. NoData value. Usually 0 or -9999 (optional).
EXAMPLE USAGE:
This example shows how to use this program on the
Linux command-line (typically a BASH shell).
Using Sentinel 2A imagery:
$ red=T34SDH_20180830T093029_B04_10m.jp2
$ green=T34SDH_20180830T093029_B03_10m.jp2
$ blue=T34SDH_20180830T093029_B02_10m.jp2
$ NIR=T34SDH_20180830T093029_B08_10m.jp2
$ VegetationClassification
--red $red
--green $green
--blue $blue
--nir $NIR
--trees trees.shp
--nontrees not_trees.shp
--ntrees 3
--nodata 0
AUTHOR:
Gerasimos A. Michalitsianos
gerasimosmichalitsianos@gmail.com
Last Updated: 5 August 2019
SAMPLE OUTPUTS:
Left: RGB (Red-Green-Blue) composite a 10m resolution Sentinel 2A Scene (Hong Kong SAR)
Right: Python machine-learning forest (woods/vegetation) classification.
Left: RGB (Red-Green-Blue) composite a 30m resolution Landsat 8 Scene (Paliki Peninsula, island of Kefalonia, Greece)
Right: Python machine-learning forest (woods/vegetation) classification.
Left: RGB (Red-Green-Blue) composite a 10m resolution Sentinel 2A Scene (Karavomilos and Sami, island of Kefalonia, Greece)
Right: Python machine-learning forest (woods/vegetation) classification.
@AUTHOR:
Gerasimos Michalitsianos
gerasimosmichalitsianos@gmail.com
August 2019
