which application is my application in illustrative visualization?

just now i am clean up my printed paper, and find recently i read much more bilateral fitler related paper than illustrative visualization. Last day I read a illustrative visuaizatin, I occure to find I havn't understand that paper. In the begining, I always think I have get that paper. but when I find a equation abou the opacity, i know i havn't make this paper sense. After carefully reading, I know all illustrative visuaslization still make some new opaicty equation, give them a new item to multiply the preliminary  formula. It just expand the cutway occlustion  1 and 0 to a continous variable between 0 and 1.then combine the occlusion with the importance value.

Now I think i need to change my way : not only reading paper, for learning the what is illustrative visualization, and how it goes. I need to get a application problem, and then based on application to read paper, and when reading paper think these method can be used for my application. But which problem is suited for me? line, normal, depth? which is suitable?

In my brains, i always think the transfer function, and just the in volume data. However, in recnet paper many researchers provide some new idea based on mixed data : segmentated data and raw volume data. I need to expand my brain, not just in the transfer function, raw volume data.