For faster preview renderings use the Render Area Rectangle to render just a small part of your scene
To turn this option ON select Render Area Rectangle from Display pull-down menu.
Move and resize the rectangle in the modeling window.
RenderZone render the scene and observe only the area inside the rectangle is rendered, which is much faster than rendering the entire scene.
Make any desired changes to lights or materials. You can even move and resize the rectangle again and the original rendered area remains on the screen.
RenderZone render again and observe only the area inside the rectangle is rendered.
This feature not only speeds up preview renderings it also let’s you compare and contrast changes to lights and materials by overlaying multiple renderings simultaneously.
