Photon Tracing

Video captions: In the following, for the demonstration of photon tracing, we create a cube as a special environment. Open the Scene menu in the menu bar and create a box, via Create Geometry. If necessary, position the box with space around your object. Open the Render Settings, via the Quick Access Bar, and under Raytracing Quality, in the Illumination Mode section, in for Interactive and Still Frame, Full Global Illumination. The render view appears black, as the object is not being lit by any light source. All up the Light Editor, under Scene, in the main menu bar. With the help of the right mouse button, open the Light Editor context menu and create a new light source. Alter the type of the light in the Area Light section, under Shape, into a Sphere light. Increase the Intensity of the light to the value of 10 and scale your light source with the help of the Transform parameter, which you can call upon via the Quick Access Bar. Position the light source as you please. Open the Render Settings and select the Photo Tracing section. Under Mode, choose Indirect Only to enable photon tracing. Indirect lighting of the scene is exclusively displayed by photons. To demonstrate this, we switch the Mode from Full Global Illumination to Precomputed + IBL. As you can see, the only difference for the indirect lighting is the emitted photons. In Full GI, you additionally have glossy reflections. You, actually, only have indirect lighting where photons land. It’s important to strike a good balance between the number of photons and the radius to illuminate the whole scene. The optimal case in reality would be an infinite amount of photons with an infinitely small radius. As this is not possible, an estimation is attempted with values like count and radius to reach a satisfactory result. With Photon Radius, you can control the radius of a single photon. Activate Antialias. You can see that no noise-free image is generated. This signals that the balance between the count and the radius has not yet been found. Change the radius and the count of the photos respectively. By increasing the count and scaling the radius, more dark areas were able to be covered by photons, reducing the noise. You have the possibility to enable Use Automatic Photon Radius, to ensure that no dark areas appear in the image. Here, depending on the number of photons, the result can occasionally be falsified.