On Set Data Capture
V-Ray’s image-based lighting systems work well for the type of work Iloura’s team does – creature work, hard surface modelling and integrating digital set extensions, buildings or vehicles. IBL is fairly new in the V-Ray renderer. The dome light supports arbitrary texture maps that determine the amount of light coming from each direction on the virtual dome hemisphere. V-Ray then uses importance sampling to trace more rays in the directions where most of the light is coming from. This method can be faster and produce a better result than with pure gathering GI.

The team frequently carries out accurate HDRI and Civetta capture while on set, which they can plug into the VRay Dome Light system to create physically accurate area lights. This facility means they can bring shots close to completion very quickly, early in the schedule, and by storing them in the application’s GBuffer file, use those same elements later in the workflow to refine the shots to look exactly as required.

GBuffer is a collection of data generated during image rendering such as Z-values or material or object IDs which is useful for compositing. V-Ray supports multi-layered G-Buffer output used by several 3ds Max render effects, and automatically generates the g-buffer channels for the image output and render effects without manual selection.

Skin Shader
Drew said, “In ‘Don’t Be Afraid of the Dark’, the FastSSS2 skin shader was critical to the look we were able to achieve for subsurface scattering, due to its speed and efficiency in handling.” VRayFastSSS2 is a material that calculates a sub-surface scattering effect for rendering of translucent materials like skin  marble with a simplified algorithm speed and better control.

It simulates the effect of three sub-surface layers - a specular layer, a diffuse layer, and a sub-surface scattering layer. You can control these separately to achieve different looks for the surface. The sub-surface scattering layer includes single and multiple scattering components. The V-Ray prepass system is used to simulate and interpolate the sub-surface scattering.

“‘Ghost Riders: Spirit of Vengeance’ was interesting because it involved about 400 shots with a flaming skull,” Drew said. “Though there wasn’t a larger than usual lighting element, being able to read the skull underneath the flame was essential, while keeping it well integrated with the plate. We started by using a dome light with the HDR data captured on set for the environment, and then removing any direct lights that we wanted to control individually. By setting up separate lights, we could then bring the work into compositing and balance out each element individually until we were satisfied.”

Stereo Support & Control
Ghost Riders was also shot in stereo, so the V-Ray StereoRig helper was good support for the team. On full CG shots, they used the frame buffer to visualize the results and check the correctness of the depth setting very quickly. It allows you to view all render elements in a single window and switch between them, and do basic colour correction to the rendered image.

The VRayStereoscopic object is a helper added to scenes to assist with stereoscopic render set-ups. The helper allows you to define two virtual cameras either based on a selected render camera and the VRayStereoscopic settings, or explicitly through the VRayStereoRig controller that combines the positions of two separate cameras for stereo rendering. With or without stereoscopy, the built in support for shade maps can speed up rendering of depth of field and motion blur effects in the images.