Mutable

If the pair is a dictionary with a key type, it’s a mutable. There are three types of mutables:

• Camera where we are

• Geometry the things we want to see

• Light how we see things

Each mutable consists of attributes. Each key-value pair of a mutable is an attribute. An attribute can be a Mutable Attribute, which mutates per frame.

Available attributes of mutables are:

Name	Type	Description
type	string	The type of the mutable, camera, geometry, or light.
count	int	The number of identically defined mutables
tracked	bool	If the mutable is tracked, its 2D/3D bounding boxes will be output, and it will have a corresponding highlighted color on the segmentation mask.
transform_operators	list	The transformation of the object.

Transform operators

Specially, to define its pose in space, the mutable can define a sequenced list of transform operators. A transform operator is also a key-value pair, in which the value can be a mutable attribute.

Shader attributes

In Omniverse, a shader has many attributes describing how a mesh is shaded. For example, diffuse_texture that points to the RGB image, and texture_rotate that specifies how its texture should be rotated. In ORO, you can control these attribtues just like any other mutable attributes. For example, the following description randomizes the tint, and rotates and scales the texture:

mesh:
  type: geometry
  subtype: mesh
  usd_path: omniverse://content.ov.nvidia.com/NVIDIA/Assets/ArchVis/Residential/Furniture/Desks/Desk_01.usd
  transform_operators:
  - rotateXYZ:
    - -90
    - 0
    - 0
  shader_attributes:
    texture_rotate:
      distribution_type: range
      start: -180
      end: 180
    diffuse_tint:
      distribution_type: range
      start:
      - 0
      - 0
      - 0
      end:
      - 2
      - 2
      - 2
    texture_scale:
      distribution_type: range
      start:
      - 0.2
      - 0.2
      end:
      - 0.7
      - 0.7

Specially, we can do common computer vision operations such as color mapping to a mesh that has a RGB image as diffuse texture by doing:

shader_attributes:
  diffuse_texture:
    distribution_type: texture
    operation: color_map

Available options are: color_map, transform, add_noise, apply_blur, color_shift, invert_color, sobel_edges, and random_mutation.

Name, count and index

A mutable has a name which is the key in the key-value pair, and potentially an index, if defined in group with a count attribute. For example, this mutable:

mesh:
  count: 2
  ...

During initialization stage, two mutables are initialized after the description is parsed. For example:

mesh_0:
  count: 2
  index: 0
  name: mesh_0
  ...

mesh_1:
  count: 2
  index: 1
  name: mesh_1
  ...

The count is still there so that you can access how many mutables are in the group. You can use these values to define macros.