Between this slide and the previous slide (slides 27 and 28), I'm not quite sure how increasing p leads to and increase in reflection. I think it was during this slide that Professor Ren had made this observation, but it seems like from the last image that as p increases, the reflection lobe narrows. I interpreted a narrow reflection lobe as meaning less reflective, but I think I may have an incorrect understanding. Can someone help me better understand what's going on with p, and possible even k_s (what these variables generally do or mean)?
brandonlouie
After thinking about this for a little longer, I think I have a slightly better understanding of how p increases reflection (although I'd appreciate if someone could verify my understanding or correct me). I believe that reflectivity mainly comes from the max(0, n * d)^p term, and this term is equivalent to cos(alpha)^p where alpha is the angle between n and d (this equivalence is state in slide 26). Looking at the plots of cos(alpha)^p, it's clear that the reflection lobe narrows as p increases. I'm interpreting a narrowed reflection lobe as meaning the reflectivity of an object is more concentrated over a smaller range or area. So, we can expect that at points where the vectors n and h are more similar (i.e. the angle between n and h is closer to 0) that the reflectivity is significantly greater than of areas where n and h are less similar. If we had a smaller value of p, we might expect that the reflectivity is more spread across an object because the reflection lobe is wider. Is this the correct interpretation?
stephanie-fu
What kinds of physical factors can affect p? From this image, it looks like texture of the surface is a factor, which makes sense. Do surface geometry and type of light source also factor into this exponent, or are they considered elsewhere?
Between this slide and the previous slide (slides 27 and 28), I'm not quite sure how increasing p leads to and increase in reflection. I think it was during this slide that Professor Ren had made this observation, but it seems like from the last image that as p increases, the reflection lobe narrows. I interpreted a narrow reflection lobe as meaning less reflective, but I think I may have an incorrect understanding. Can someone help me better understand what's going on with p, and possible even k_s (what these variables generally do or mean)?
After thinking about this for a little longer, I think I have a slightly better understanding of how p increases reflection (although I'd appreciate if someone could verify my understanding or correct me). I believe that reflectivity mainly comes from the max(0, n * d)^p term, and this term is equivalent to cos(alpha)^p where alpha is the angle between n and d (this equivalence is state in slide 26). Looking at the plots of cos(alpha)^p, it's clear that the reflection lobe narrows as p increases. I'm interpreting a narrowed reflection lobe as meaning the reflectivity of an object is more concentrated over a smaller range or area. So, we can expect that at points where the vectors n and h are more similar (i.e. the angle between n and h is closer to 0) that the reflectivity is significantly greater than of areas where n and h are less similar. If we had a smaller value of p, we might expect that the reflectivity is more spread across an object because the reflection lobe is wider. Is this the correct interpretation?
What kinds of physical factors can affect p? From this image, it looks like texture of the surface is a factor, which makes sense. Do surface geometry and type of light source also factor into this exponent, or are they considered elsewhere?