We Need Bettter Bump mapping to be implemented in corona. Bump Roughness similarly to what is being used in Renderman and it will gets you a good result from any distance which solves the Bump Filtering issues currently affecting Corona.
Someone posted about it previously
https://forum.corona-renderer.com/index.php?topic=38682.msg212955#msg212955And Please can it be added to the Most Wanted Features List. Thanks