Here is a quick tip on how to add hard shadows to any HDRI image. A lot of HDRI have very soft shadows not matter how much you adjust the contrast. This trick lets you control how hard the shadows are your scene.
Jon Hull shows how to make and use transparent textures in KeyShot. Using transparent .tif images for color maps has several advatages over normal color maps. This tutorial will show you how to create these images to use in KeyShot.