While these quick modes, such as Lighting, Normals and UVs, can quickly help an artist figure out what is going on, the Isolate Selected option is the real power of this feature. When choosing this option, V-Ray will only render with what is selected; this includes objects, shaders and even lights. To better understand this, here are some examples:
- Within one of your scenes, select an object, or a group of objects, while in the Isolate Selected mode. V-Ray will only render those objects that you see. Everything else will be black.
- Select a single light or a group of lights. Now it will render the whole scene, but only take into consideration the light(s) you've selected. You can use this to isolate the contribution of that light and change its values or position on the fly.
- Finally, choose an object that you want to adjust shaders on, and then expose that shader graph in Hypershade. When you select any node with the graph, V-Ray will only render the object up to that point in the graph; this allows you to precisely see what each portion of the shader is contributing to the actual rendering.
Now, let’s say you've selected a series of objects and a few lights, and you want to adjust a shader but still see the rendering based on your current selection — then you can switch the Debug Shading mode to Isolate Locked Selection. This way, you don’t lose your current selection set as you continue to adjust values.
In addition, you can use the Debug Shading mode in combination with the AI Denoiser — and even playblast it if you want to.
This makes it one of the best tools to fine-tune and see exactly what is going on in the different parts of your scene.
This video will give you an even better idea of how the Debug Shading works on a scene: