V-Ray Gaussians

This page provides information about the Gaussian splats geometry in V-Ray for Cinema 4D.

Overview

3D Gaussian Splatting is a method for creating a 3D scene from images or videos. It requires several pictures of an object, each taken from a different angle. With Gaussian Splatting, the images are blended to produce a detailed, three-dimensional representation of the object. Instead of depicting the scene as a collection of meshes, a Gaussian splat represents the scene as a type of point cloud, where each point is a 3D Gaussian.

Gaussian splats help you create a realistic environment for your scenes.

UI Path: ||V-Ray menu|| > Geometry > V-Ray Gaussians

Gaussian Splats Usage

Used as Extended Environment

One use of Gaussian splats is to represent an environment, typically generated from photos or videos of the scene.

There are advantages over the traditional environment maps, including proper parallax and view-dependent effects and the ability for Gaussian splats to occlude other objects in the scene.

For Gaussian splats to work as environments in V-Ray, the Affect Matte Surfaces option should be enabled, and the Affect Shadows option should usually be disabled.

See the example for more information.

On Other Matte Surfaces

To make the Gaussian splats rendered as part of the background, i.e., visible on other matte objects even if they are behind them. This is achieved by enabling the Affect Matte Surfaces option from the parameters.

See the example for more information.

Used as Individual Objects

Gaussian splats can also be used to represent smaller individual objects in the scene. In that case, the Affect Matte Surfaces option typically is turned off, and the Affect Shadows option is enabled. The latter is needed so that the Gaussian splats can cast proper shadows on other objects in the scene.

Note that the lighting and reflections are baked into the Gaussian splats objects, and therefore these objects are not affected by the scene lighting.

See the example for more information.

General

Gaussian Splat File – Loads the Gaussian splats file. Currently, only .ply files are accepted.

Clipping Mask Enabled – The Clipping mask can be used to include or exclude areas of a splat or blend between two or more splats with the help of additional objects (primitives). Attach a V-Ray Distance texture (Node or Classic) to the Clipping Mask field. The properties of the Distance texture determine the properties of the clipping. 3D procedural textures are also supported as clipping masks.

Material Tag – Allows a material tag to be attached to determine the UVW mapping of the clipping mask.

Scale – Scales the Gaussian splats up and down. See the example.

Flip Axis – Controls which axis is used as a vertical - the Y or Z axes for the loaded file. You can choose between:

As Is – No changes in the axes are applied.
Rotate YZ– Switches the Y and Z axes.
Rotate XZ + Flip Y – Switches the X and Z axes and flips the Y axis.

Affect Camera – Specifies whether the Gaussian splats should be visible to the camera. See the example.

Affect Shadows – When enabled, Gaussian splats block shadows from lights. When disabled, the Gaussian splats become transparent to shadow and GI rays. It is recommended that this option be turned off when using the Gaussian splats as environment or individual objects. See the example.

Affect Reflections – Specifies whether the Gaussian splats should be visible in reflections. See the example.

Affect Refractions – Specifies whether the Gaussian splats should be visible in refractions. See the example.

Affect Matte Surfaces – When enabled, Gaussian splats appear as part of the background on matte surfaces. It is recommended to enable this for Gaussian splats used as an environment and disable it for Gaussian splats used as individual objects. See the example.

Color Space – Specifies the color space of the data in the Gaussian splats file.

Default – Takes the current color correction that is set in Maya. That means it does not change the colors.

To read the Gaussian splats file as it was written, select the respective input color space - sRGB, ACEScg, or Raw.

Intensity – Increases or decreases the Color multiplier for the Gaussian splat.

Color – Specifies a filter color for the splat. By default, the Color is white, which does not affect the splat. See the example.

Lighting

Lighting On – Enables the lighting for this gaussian instance. See the example.

Lighting Blend – Specifies the blending ratio between the splats' original color and the illuminated result.

Lighting Shadow Blur – Specifies the blur distance of the illumination in world units.

Lighting Shadow Offset – Offset for computing the illumination in world units.

Lighting Normals Mode – Determines how normals are treated when computing Gaussian Splats.

Disabled – Disables normals when computing the lighting.
Intrinsic (compute if Needed) – Forces the usage of computed normals, ignoring any intrinsic normals.
Computed (force Calculation) – Uses intrinsic normals, if they are present. Otherwise, computes normals from scratch.

Preview

Type – Specifies how the Gaussian splats are rendered in the viewport.

Disabled – The Gaussian splats are not visible in the viewport and cannot be selected from there. You can select them from the Object Manager only.
Bounding Box – The Gaussian splats are represented by a bounding box.
Limited Point Cloud – This is the default mode. The Gaussian splats are represented by cloud points in a bounding box. The bounding box is restricted by the Point Radius and the Point Count.
Unlimited Point Cloud – The Gaussian splats are represented by cloud points in a bounding box. The bounding box is restricted only by the Point Radius.

Point Radius – Determines the radius around the Gaussian geometry, where the cloud points are visible in the viewport. This option works when the Type is set to Limited/Unlimited Point Cloud.

Point Count – Determines the exact number of points to be visible in the viewport. This option works when the Type is set to Limited/Unlimited Point Cloud.

Example: Scale

This example shows Gaussian Splat used as an individual object - the pink flamingo floatable in this scene. Using the Scale parameter, it can be scaled as any other object in the scene.

Scale = 0.5

Scale = 1

Scale = 1.5

Example: Affect Camera

The Gaussian Splats object can be hidden from the camera, like any other geometry object in the scene, by using the Affect Camera option.

On

Off

Example: Affect Reflections

The Affect Reflections option controls if the Gaussian splats object is reflected in other objects in the scene.

Off

On

Example: Affect Refractions

The Affect Refractions option makes the Gaussian splats object seen by other objects in the scene that exhibit refractive properties.

On

Off

Example: Affect Shadows

This example shows how the pink flamingo can produce shadows when the Affect Shadows option is enabled, and doesn't block light when it's not.

On

Off

Example: Affect Matte Surfaces

In this example, the Gaussian splat is used as an environment. The left building in the rendering that casts shadows over the plane, is a Cosmos asset (mesh).

When the Affect Matte Surfaces option is enabled, the Gaussian splat is considered as background and receives shadows from the casting object.

On

Off

Example: Color

The Color shown on each render as a box is used as a filter for the original Gaussian splat diffuse color.

Example: Lighting On

This example shows how adding light in the scene and then enabling the Lighting On property affects the render.

No Light in the scene. Splat has baked-in light, but geometry is dark.

V-Ray Sun added to the scene. The building is lit, but the Splat does not receive that light.

Lighting On enabled. Both the building and Splat are lit by the V-Ray Sun, but the light does not correspond to the baked-in light of the Splat.

The V-Ray Sun is positioned to match the lighting direction of the light in the splat.