Unsupervised Learning::Satellite Images::Single Bands

Question

Unsupervised Learning::Satellite Images::Single Bands

OctoCatKnows

2022年2月8日 12:08

Has anyone has success with building models using KMeans for classification? I have images that only have one band and it continues to fail. My guess is that the issue is with both size of the image as well as the single band.

For example:

from osgeo import gdal,gdal_array
import numpy as np

src = '/Path/ImgA.TIF'
img_A = gdal.Open(src)

#Getting bands (count)
bands_n = img_A.RasterCount  #returns 1

band = img_A.GetRasterBand(1)

#read as array
band_arr = band.ReadAsArray()

band_sh = band.shape

#eg. output#
300,300

//This is where I am getting stuck. If I pass only two inputs (rows/cols) to KMeans, it fails as it requires a 2D array not 1D. It also fails when I manually set the band://

#Attempt 1
rows, cols = band_sh

#Attempt 2
rows, cols, band = band_sh, 1 

X = band.reshape(rows*cols,band) // X = band.reshape(rows*cols,1)

from scikit.cluster import KMeans

kmeans = KMeans(n_classes = 2, random_state=2).fit(X)

Any ideas? This works just fine with RGB but fails each time when dealing with rasters that are single band.

Topic image-classification geospatial scikit-learn k-means

Category Data Science

Bruno Lubascher · Accepted Answer · 2019年12月12日 08:09

it fails as it requires a 2D array not 1D

The X in .fit(X) is 2D, where each row is one training point and the columns are the features of that training point.

It should be a list of lists:

X = [
  [feature_1, feature_2,....feature_n], # training point 1
  [feature_1, feature_2,....feature_n]  # training point 2
  .
  .
  .
  [feature_1, feature_2,....feature_n]  # training point 123
]

The K-Means will train with all the examples in X.

However, you are only giving 1 training example, namely img_A. So your X is like this at the moment:

X = [feature_1, feature_2,....feature_n] # img_A

So, to .fit() K-Means, you need more image examples.

Unsupervised Learning::Satellite Images::Single Bands

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