The Gaussian Splat shape renders point-based scene representations composed of millions of oriented volumetric splats instead of traditional polygonal geometry. Gaussian splats are commonly generated from photogrammetry, neural rendering, or radiance field reconstruction workflows and provide an efficient way to represent highly detailed real-world captures.

Each splat is represented as an anisotropic 3D Gaussian distribution defined by:

• Position — center of the splat in 3D space
• Scale — ellipsoid size along each axis
• Orientation — rotation of the ellipsoid
• Color / Radiance — emitted or reflected appearance
• Opacity — transparency contribution

During rendering, Arnold projects and blends splats together to reconstruct continuous surfaces and volumetric detail with smooth transitions and high visual fidelity.

The Gaussian Splat shape loads and renders Gaussian splat datasets inside Arnold. These parameters control file loading, viewport display, color handling, and advanced rendering options.

File/Frame

Path

Specifies the Gaussian Splat file to load (PLY).

Use File

When enabled without a mask mesh, passes the file path directly to Arnold for efficient on-demand loading. When disabled, MtoA reads and inlines the PLY data at scene translation time. Inlining also occurs automatically when a mask mesh is connected, regardless of this setting.

Up Axis

Specifies the coordinate-system convention used by the source splat file. Set this to match how the splat dataset was authored so that the data is oriented correctly in the scene.

• Y up — Identity (Maya default).
• Z up — Source +Z maps to +Y (−90° rotation around X).
• -Y up — Source −Y maps to +Y (180° rotation around X).
• -Z up — Source −Z maps to +Y (+90° rotation around X).

Min Pixel Width

Defines the minimum on-screen size of individual splats in pixels. Increasing the Min Pixel Width (MPW) can help reduce holes and sparse regions, improve the visibility of distant splats, and produce smoother surface reconstructions. Lower values preserve finer detail but may introduce gaps or aliasing in thin regions.

For best results, use an MPW value close to 1.0. Setting MPW too low may cause visible holes or missing coverage.

Shading

Controls how each splat's stored color and radiance data is interpreted, shaded, and combined into the final image.

Input Color Space

Specifies the color space used to interpret splat color data. Choose the color space that matches the source dataset to ensure accurate shading and lighting.

Emission Weight

Scales the contribution of each splat's stored radiance, treating splat color as emitted light. A value of 1.0 renders splats at their captured brightness; 0.0 disables the emission contribution.

Emission Tint

Applies a color multiplier to the emission component of each splat. White preserves the original captured color; other values shift the emitted appearance for look development, grading, or matching scene lighting.

Diffuse Weight

Scales the diffuse shading contribution from scene lights. Use a non-zero value to have splats respond to Arnold lights; set to 0.0 for an unshaded, radiance-only look.

Note that the fish in the example below is a polygon mesh. This demonstrates that Gaussian splats can be mixed with meshes, curves, and volumes in the same scene, while still supporting ray-traced effects such as reflections and refractions.

Diffuse Tint

Applies a color multiplier to the diffuse component of each splat.

Diffuse Roughness

Controls the roughness of the diffuse response. Higher values produce a flatter, more uniform diffuse falloff across each splat.

Masking

Restricts splat rendering to a region defined by a polygon mesh.

Mask Mesh

Specifies a polygon mesh that masks the splat rendering. By default, splats inside the mask mesh are removed and only those outside are rendered. This is useful for cutting away a region of a large splat capture.

To select a Mask Mesh:

1. Click the pick icon
2. Click an object in the scene or Outliner
3. Press ENTER to add the object to the Mask Mesh field

Alternatively, you can manually connect the object's shape node Out Mesh to the Mask Mesh of the Gaussian Splat.

_{All Arnold > Visibility attributes disabled for mask mesh}

Invert Mask

When you enable Invert Mask, Arnold renders only the splats inside the mask mesh instead of outside.

Display

Controls viewport visualization behavior.

Draw Mode

Determines how the Gaussian splats are displayed in the viewport.

• Bounding Box — Displays only the object bounds for maximum viewport performance.
• Point Cloud — Displays the splats as colored points for lightweight visualization and interaction.
• Gaussian Splat — Displays the splats using depth-sorted, alpha-blended 2D projected quads. This provides a higher-fidelity viewport preview than Point Cloud and closely approximates the original 3DGS appearance, though it differs from Arnold's ray-traced output.

Display Percentage

Specifies the percentage of splats shown in the viewport. Lower values improve interactive performance when working with large datasets. This setting does not affect final render output.

Max Display Points

Limits the number of splats shown in the viewport. This parameter improves interactive performance when working with large datasets. Lower values provide faster interaction while higher values improve viewport fidelity. This setting does not affect final render output.

Advanced

User Options

A text box for Arnold points node parameters and values (Gaussian splats are rendered as Arnold points).

You can use this to set points parameters. For example: mode sphere radius 0.01