Why there are two clipping planes here to represent the render area? Personally, I think the front clipping plane is because of the distance between eye and retina? And the back clipping plane is to get depth information? I am not sure my understanding is correct or not.
I had the same question about the purpose of the clipping planes. I think that the back clipping plane is used to limit the computational power needed to render a scene, but I am still unsure about the front clipping plane. Additionally, if an object is halfway into the front clipping plane, after clipping the image, we are left with a cross section of the object. It seems computationally expensive to have to check for objects that are sliced by the clipping planes and remove them.
A lot fo times clipping is indeed used to improve performance. Other times, front clipping is important because we want to leave enough numerical precision for the depth information objects farther away. For an excellent explanation of the latter, see https://computergraphics.stackexchange.com/questions/2310/could-we-dispense-the-near-clipping-plane
Maybe I am misunderstanding what the clipping planes are but how exactly do we determine where to place them? My understanding is that as you shift the volume closer to the fixed position COP your will essentially be zooming in the image. Is this how we zoom in and out with a camera or is this whole idea strictly regarding depth?