Which of these are valid types for custom attributes in OpenUSD? (Choose two.)
Correct Answer: B, C
Explanation:
Custom attributes in OpenUSD are user-defined properties authored on prims to store additional typed data beyond predefined schema attributes. NVIDIA’s Learn OpenUSD material states that custom attributes can hold “numeric values, strings, or arrays,” and that custom attributes are created with UsdPrim::CreateAttribute(), where Sdf.ValueTypeNames represents the attribute type. NVIDIA’s OpenUSD data type reference lists Asset with the USDA value type token asset, and String Array with the USDA token string[], making asset paths and string arrays valid attribute value types.
Option B is correct because asset path values are represented through the asset value type and are commonly used for resource references such as textures or external asset identifiers. Option C is correct because string[] is a valid array value type. Option A is incorrect because USD does not have a native struct attribute type; NVIDIA recommends namespace-prefixed attributes for mapping grouped or compound fields. Option D is incorrect in this context because dictionaries are associated with metadata/customData patterns, not ordinary typed custom attributes. This aligns with Customizing USD → Custom Properties, Sdf.ValueTypeNames, Name spaced Attributes.
Question 2
When prioritizing ease of interchange and reducing dependencies between different applications in a pipeline, why might codeless schemas, schemas defined purely in .usda files, be preferred over codeful schemas, schemas with generated classes using usdGenSchema?
Correct Answer: A
Explanation:
Codeless schemas are preferred when the pipeline goal is portability, easy distribution, and reduced application coupling. NVIDIA’s Learn OpenUSD schema guidance states that schemas define data models and optional APIs for encoding and interchanging 3D and non-3D concepts, and notes a trend toward codeless schemas for easier distribution, with schemas becoming more focused on data modeling rather than behavior implementation.
Option A is correct because a codeless schema can be distributed as schema data and plugin metadata without requiring every consuming application to compile, link, or ship custom generated C++/Python schema classes. OpenUSD’s schema-generation documentation identifies codeless schemas as schemas produced without corresponding C++ classes, where only generatedSchema.usda and plugInfo.json are essential for runtime registration. Option B is incorrect because strongly typed convenience APIs are the advantage of codeful generated schemas. Option C is incorrect because fallback values are authored in schema definitions. Option D is incorrect because codeful and codeless schemas can both participate in schema registration and value interpretation. This aligns with Customizing USD → Schemas, API Schemas, Codeless Schemas, Schema Registry, Data Modeling for Interchange .
Question 3
Why is usdchecker an important part of data exchange?
Correct Answer: A
Explanation:
usdchecker is important in data exchange because it validates whether exported USD or USDZ assets comply with rules that make them more likely to be interchangeable, renderable, and usable by downstream consumers. NVIDIA’s Learn OpenUSD Asset Validation lesson states that usdchecker validates a USD stage or USDZ package using defined rules to provide the best assurance that an asset will be properly interchangeable and renderable by Hydra. It is presented as part of the data exchange workflow for testing converter output and improving exporter quality.
Option A is correct because asset validation directly supports downstream consumption, which is the core goal of data exchange. A converter may write syntactically valid USD but still omit important metadata, invalid extents, default prims, unresolved dependencies, or other requirements that reduce interoperability. Option B is incorrect because usdchecker does not require binary .usdc output. Option C is incorrect because validation is not optimization. Option D is too narrow; URI and asset-path checks may be part of validation, but they are not the primary purpose. This aligns with Data Exchange → Asset Validation, usdchecker, Converter Testing, USDZ Compliance, and Downstream Interoperability .
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