VRAY FOR 3 DS MAX Volumetrics LESSON INTRODUCTION

V-RAY FOR 3 DS MAX Volumetrics

LESSON INTRODUCTION Orientation • This presentation covers the use of the V -Ray Aerial Perspective and V-Ray Environment Fog effects in 3 ds Max • This lesson topic is approximately 40 minutes in length • This presentation covers all three learning cycles: Lecture, Demonstration and Activity

RANDOM COLORS • Objective – We will use the V -Ray Aerial Perspective and VRay Environment fog atmospheric effects to add a fog effect to our scene • Outcome – You will be able to properly setup the V-Ray Aerial Perspective and V-Ray Environment fog atmospheric effects Artwork by Name

VOLUMETRICS V-Ray Environment Fog • The V-Ray Environment Fog allows us to simulate effects like fog, dust, smoke or other tiny particles floating in the atmosphere • The effect can be confined within the boundaries of a gizmo or any geometry • We can control which light sources contribute to the effect • V-Ray performs ray tracing, including GI, within the fog which creates physically accurate results with volumetric light and shadows • Textures can be used to control the fog but ray tracing through the volume can be slow • Emissive component allows us to fake GI in the volume without having to calculate it

V-RAY ENVIRONMENT FOG General Parameters • fog color – the color attenuation of the fog • fog distance – controls the fog density. Larger values make the fog more transparent • fog emission – allows us to add a selfillumination color to the fog to fake GI bouncing within it • scatter GI – when enabled global illumination will be calculated for the fog. This can be quite slow hence we suggest using the fog emission. • scatter bounces – when the scatter GI check box is enabled this parameter controls how many times a ray of light bounces within the fog

V-RAY ENVIRONMENT FOG General Parameters • fog height – puts a limit on how far the fog reaches along the Z axis • step size – when we use textures to control the fog parameters V-Ray needs to sample the fog in steps starting from the camera and moving into the volume of the fog. This parameter determines the distance each ray travels before taking the next sample. Higher values are faster to calculate but may miss some fine detail in the texture. • cutoff threshold – when V-Ray is tracing inside the volume it accumulates information about the transparency. This parameter tells V-Ray when to stop. If the transparency is below this level any additional tracing will not have a visible effect so V-Ray will stop the ray tracing

V-RAY ENVIRONMENT FOG Maps • fog color – a texture slot to control the color attenuation of the fog • density texture – a texture slot to control the density of the fog. The values in the texture are multiplied by the fog distance parameter to get the actual density • fog emission – a texture slot to control the selfillumination color of the fog

V-RAY ENVIRONMENT FOG Ray filter • The options in this section allow us to speed up the rendering of the Environment Fog by disabling it from affecting certain calculations. • affect background – when disabled the background will not be obscured by the fog • affect reflections/refractions – specifies whether the fog will be visible in reflections/refractions • affect shadows – When disabled the fog will not generate volumetric shadows • affect GI – when disabled the fog will not affect the calculation of GI for the rest of the scene • Affect camera rays – when disabled the fog will not be visible directly by the camera.

V-RAY ENVIRONMENT FOG Nodes • Gizmos – a list of gizmos or geometries within which the V-Ray Environment Fog will be contained • Use all lights – when enabled all lights will affect the V-Ray Environment Fog. When disabled only the lights in the list below will affect the fog.

VOLUMETRICS V-Ray Aerial Perspective • The V-Ray Aerial Perspective allows us to simulate the effect of looking at objects at a distance through the atmosphere. • The effect is similar to a thin haze and contributes to the realism of large scale exterior scenes • The resulting effect is very similar to the effect of the V-Ray Environment Fog but it is only an approximation. • The effect is much quicker to calculate than the V-Ray Environment Fog but it’s not entirely physically accurate i. e. volumetric shadows are not calculated

V-RAY AERIAL PERSPECTIVE General parameters • visibility range (in meters) – specifies the distance at which the fog has absorbed 90% of the light coming from behind it. Lower values make the fog look more dense • atmosphere height (in meters) – specifies the height of the fog • inscattered light intensity – a multiplier for the brightness of the light scattered within the fog • filter color – allows us to tint the color of the fog

DEMONSTRATION Volumetrics Sit back and watch as I demonstrate how to set up the V-Ray Environment Fog and the V-Ray Aerial Perspective atmospheric effects…

ACTIVITY Volumetrics Now it’s your turn. Use the provided scenes and handouts to experiment with the V-Ray Environment Fog and the V-Ray Aerial Perspective atmospheric effects…