Just want to ask one question regarding the classification using the hyperspectral or Multi-spectral data, If we have hyperspectral or Multi-spectral data, and we only use the data of R G and B frequencies and we got the good classification result. Does it make sense? Or we have to use all the possible the frequencies which have the information.
Assuming your accuracy assessment is valid and you are satisfied with the classification accuracy, by all means use only the visible spectrum bands. Many studies limit the spectral bands to the visible spectrum and near infrared for processing purposes or to maintain native spectral resolution. This is completely valid depending upon your research question and the desired results.
However, incorporating additional spectral information into your land cover classification will almost always increase your accuracy and decrease your commission and omission error rate. Therefore, unless you have some very particular reason not to incorporate the additional spectral information, I would opt to use it.