I was trying to find out how much of your scene is rendered in vue 10 that is not seen by the camera.

If I put a tree on an empty scene out side the cameras view point the shadow cast will appear in the view. When the scene renders will it just render the shadow or the unseen tree as well? 

For example ifI want to create a Forest scene, obviously the trees outside my point of view change the light coming in so I place trees that can not be seen but their shadows can be and the way they change the light will be seen. As I always need to conserve resources when using vue I don't want to render Hi Res trees that will not be seen but take up resources. If only the shadows render then it probably makes very little difference. 

You may wonder why not just put lowRes trees out side the

cameras view, it just saves swapping them round if I need to adjustment the cameras position. Hope I've managed to explain this clearly enough, thanks in advanced for any help

HopeI've e

Sorry for mistakes writing this on my phone while over is busy and a bit difficult to correct anything.

If a pixel in your rendered frame can be ray-traced back to a tree, it will render/generate data for that tree.  In general, if the tree is off camera, just the lighting calculations from it are used (like GI and GR), which is almost like rendering the tree anyway.  Some trees glow their leaf colors, depending on their materials used.  Their alpha mask is certainly generated though to get the shadows to appear in your frame.

But being off camera, there will be hardly any photon bouncing within leaves/branches of trees and certainly no applying of any AA to the rendering of them.  So the CPU and RAM will skip over most of that process while rendering.  But the trees will still occupy scene RAM.

ok thanks that seems clear enough maybe worthwhile using low rez trees off camera

ShawnDriscoll makes a good and important point with his wording...calculations in the render engine are made from the "camera" (rendered frame) out. This is one door in the process in which optimization is utilized in the code.