Class Project Report: Supervised Classification and Unsupervised Classification

This project use migrating means clustering unsupervised classification (MMC), maximum likelihood classification (MLC) trained by picked training samples and trained by the results of unsupervised classification (Hybrid Classification) to classify a 512 pixels by 512 lines NOAA-14 AVHRR Local Area Coverage (LAC) image. All the channels including ch3 and ch3t are used in this project. The image is classified to six classes including water, vegetation, thin partial clouds over ground, thin clouds, low/middle thick clouds and high thick clouds plus unknown class for supervised classification. In total, the results using these three methods are very consistent with the original three-band overlay color composite image and the statistical mean vectors for each class are consistent using different methods and are reasonable. We also note that the ch3t temperature is usually much larger than the thermal channel-measured temperature for clouds, the colder the thermal temperature, the larger their difference. The ch3 reflectance is anti-correlated with the ch1 and ch2 reflectance, which is due to that high reflectance ice clouds can absorb most of the energy in this channel. Look carefully, the results of MMC and MLC trained by the results of MMC are better than that of the MMC trained by picked samples. The MLC trained by picked samples produces more unknown classes than that trained by MMC, which is probably due to that the standard deviation (multivariate spreads) for each class generated by MMC is usually larger than that of picked training samples. It takes more computation time to run MMC (5 iterations) than MLC if the classes are the same, but take more time to pick samples over and over to get comparable results. The results of MLC trained by picking samples is worse than the other two methods due to the difficulty of picking representative training samples. The hybrid supervised/unsupervised classification combines the advantages of both supervised classification and unsupervised classification. It doesn’t require the user have the foreknowledge of each classes, and can still consider the multivariate spreads and obtain accurate mean vectors and covariance matrixes` for each spectral class by using all the pixels image as training samples. Class Project Report: Supervised Classification and Unsupervised Classification 2