VdbGeometry

Overview

VdbGeometry loads an OpenVdb volume file for rendering using the VdbVolume volume shader.


Attribute Reference

Geometry attributes

reverse_normals

Bool
default: False

enable to reverse the normals in the geometry

side_type

Int enum
  0 = “force two-sided” (default)
  1 = “force single-sided”
  2 = “use mesh sidedness”

set single sidedness of the mesh, will affect the visibility of the mesh based on normal direction

Labels attributes

label

String
default:

label used in material aov expresssions

shadow_receiver_label

String
default:

Label used to associate Geometry objects into ShadowReceiverSets. Using this in combination with the ["shadow_exclusion_mappings"] attribute, shadows from specified geometries or their parts can be suppressed from casting shadows onto one or more specified sets.

Motion Blur attributes

velocity_grid

String
default:

the name of vector grid representing the velocity field. Usually named "v" or "vel" in simulation export. If multiple velocity grids have the same name, only the first grid with that name will be loaded. If a vdb file has multiple grids with the same name, you may use a suffix index to pick which grid to load, e.g. "v[3]". The index must be in [] brackets. The index can be different from the index on the "density_grid".

velocity_sample_rate

Float
default: 0.2

the relative scale of input velocity grid resolution. Lower value has lower memory overhead and lower fidelity of motion blur effect, which is sometimes desired for artistic reasons

velocity_scale

Float
default: 1.0

A scale factor for the velocity field. A value of 0 disables motion blur.

Ray Tracing attributes

ray_epsilon

Float
default: 0.0

When a secondary ray is fired, anything within this distance of the intersection point will be ignored. Instead, it is considered part of the current intersection's geometry. If zero, an automatically calculated epsilon will be used.

shadow_ray_epsilon

Float
default: 0.0

When a shadow ray is fired, anything within this distance of the intersection point will be ignored. If this value is less than "ray_epsilon", then it has no additional effect.

VDB attributes

density_grid

String
default: density

The name of the density grid. If multiple grids have the same name, only the first grid with that name will be loaded. If a vdb file has multiple grids with the same name, you may use a suffix index to pick which grid to load, e.g. "density[3]". The index must be in [] brackets.

emission_grid

String
default:

The name of the emission grid. If multiple grids have the same name, only the first grid with that name will be loaded. If a vdb file has multiple grids with the same name, you may use a suffix index to pick which grid to load, e.g. "emission[3]". The index must be in [] brackets.

emission_sample_rate

Float
default: 1.0

the relative scale of input emission grid resolution. Lower value has lower memory overhead and faster render time, with the cost of lower fidelity of emission shape and illumination

interpolation

Int enum
  0 = “nearest neighbor”
  1 = “linear” (default)
  2 = “quadratic”

Voxel interpolation to use when sampling the volume data

model

String filename
default:

The VDB file to load

Visibility attributes

visible_diffuse_reflection

Bool
default: True

whether the geometry is visible in diffuse reflection

visible_diffuse_transmission

Bool
default: True

whether the geometry is visible in diffuse transmission

visible_glossy_reflection

Bool
default: True

whether the geometry is visible in glossy reflection.

visible_glossy_transmission

Bool
default: True

whether the geometry is visible in glossy transmission (refraction).

visible_in_camera

Bool
default: True

whether the geometry is visible to camera rays

visible_mirror_reflection

Bool
default: True

whether the geometry is visible in miror reflection.

visible_mirror_transmission

Bool
default: True

whether the geometry is visible in miror transmission (refraction).

visible_shadow

Bool
default: True

whether the geometry casts shadows

visible_volume

Bool
default: True

whether the geometry is visible in indirect volume rays

General attributes

contains_camera

Bool
default: False

Specifies whether the geometry contains the camera and should be used for IOR tracking. This should not be changed by the user -- they should instead attach the relevant geometry to the camera, which will then flag this geometry.

dicing_camera

SceneObject
default: None

Alternate camera that is used for adaptive tessellation. This is useful if you want adaptive tessellation to behave consistently in a sequence, regardless of what the main camera is doing

node_xform

Mat4d blurrable
default: [ [ 1, 0, 0, 0 ], [ 0, 1, 0, 0 ], [ 0, 0, 1, 0 ], [ 0, 0, 0, 1 ] ]

The 4x4 matrix describing the transformation from local space to world space.

references

Geometry Vector
default: {}

list of geometries that geometry procedural can reference during procedural generate/update stages. For example, an instancer geometry procedural can instance primitives generated by the reference geometry procedural.

shadow_exclusion_mappings

String
default:

A space-separated list of mappings of the form A:B where:
A is a comma-separated list of names of parts of this Geometry, or an asterisk to specify the whole geometry;
B is a comma-separated list of shadow receiver set labels established using the ["shadow_receiver_label"] attribute, or an asterisk to specify to all such sets in the scene.
For each of the listed mappings, shadows from the parts specified in A will be suppressed from casting onto any geometries in the ShadowReceiverSets specified in B.
**Note: no part name should appear more than once in the string, otherwise the behavior is undefined.**

static

Bool
default: True

disable if the geometry will be updated between frames

use_local_camera_motion_blur

Bool
default: False

Enables experimental feature that also attempts to remove the camera blur in the local regions

use_local_motion_blur

Bool
default: False

Enables the local motion blur feature, which makes the geometry procedural responsible for handling all of the geometry's motion and allows for custom effects