   Renderer question
  Hy!Does anyone know why do the hi-end ray-tracing renderers create the image in separately rendered small parts(small boxes) one by one? Cache optimization maybe?THX!   
  Cache optimization and multi-threading, probably.   ;  Some renderers are progressive, so they go from low to high resolution to give quicker feedback of entire image, rather than just partially rendered rows. Due to how raytracing works, this is quite cheap.   