We have been seeing many countries still don't have good resolution geological maps of their territory. In such situation remote sensing is an alternative for independent researchers. Understanding of Photogeology is the most for this.
Hello! I'm not sure what photogeology really is, however I could recommend reading "Remote Sensing Geology" by Ravi P. Gupta. Here is a link to the second edition:
Hi Susmita, there may be several books available on the topic but I think it may be worth to look at one in particular. If I remember correctly we used a reference book during Frank's Module. The name of the book was 'Image Interpretation in Geology' 3rd Edition, by Steve Drury. We were specifically focused on Chp. 4 'Photogeology' but I think the entire book is a valuable resource, beginning with principles of remote sensing, photogetology, passive and active remote sensing, GIS etc. In fact this book contained a red cyan Anaglyph paper glass to view stereo pair of images in 3D. The book cover also reads there is a CD-ROM available with the book but I did not find it in the ITC Library back then. Unfortunately, I don't have the book or the soft copy of it, but I think you can ask Tinu or simply try requesting it from ITC directly. Here is a link that I found online of the book https://www.scribd.com/doc/188027367/Image-Interpretation-in-Geology-3rd-Edition-s-a-Drury-Optimized
Assuming that you have studied geology, and if you have good quality satellite photos of an area of Nepal of particular interest, I'd suggust you might skip the books and start immediately with the best quality geological maps of the area you can find (there are several basic maps of Nepal online). Comparing the photos with the map, try to distinguish igneous and metamorphic rocks from sedimentary rocks based on their erosion characteristics. Then in the Tethys areas try to distinguish lineations caused by the outcrops of hard and soft sediments. Look particularly for loops and hairpins caused by anticlines and synclines. With concentrated effort your expertise will quickly improve and you can submit your observations to the local geological survey for consideration.