|Transparency Mapping is a method to create transparent material based on the Alpha channel of a bitmap image.|
Transparency Mapping allows you to mask your geometry with the Alpha Channel of a bitmap image. this means that parts of the image hat are black will render with a transparent material in the scene. This method can be very helpful because it prevents you from modeling the actual objects of your scene. Creating the actual objects will increase both the number of objects on the scene, as well as the rendering time. In cases where you can use Transparency Mapping instead of modeling the actual object, it is recommended that you do so, since it creates a very similar result.
To create a transparent map you should open the Material Editor . Create a new Diffuse layer, Diffuse 1, to the main material of your object. Click on the m at the right of Transparency option to open the Texture Editor . Upload the Bitmap for Transparency texture map. In the Diffuse1 layer you can adjust the diffuse color of the Transparency map. Click on the "m" at the right of Color to add more texture to this map if needed. Use Photoshop editing tools to create a black and white of your image before you upload it as a transparent maps in Vray. Use image formats such as, .png, .jpg., .bmp.