OPCFoundation.NetStandard.Opc.Ua.OpenUsdScene

Opc.Ua.OpenUsdScene

Companion information model for the draft OPC UA — OpenUSD Scene Materialization (Part 2) specification, source-generated from the shared Opc.Ua.OpenUsdScene.NodeSet2.xml.

Where the Bindings model (Part 1, Opc.Ua.OpenUsd) keeps the USD scene outside OPC UA and binds process values to it, Scene Materialization puts the scene inside the address space: the composed prim tree becomes the OPC UA node hierarchy, so browsing the server is browsing the scene.

What is in the model

The value-role DataTypes follow the OPC UA idiom of conveying meaning by extending a primitive (Duration : Double, UtcTime : DateTime), so a role such as colour versus point is discoverable from the type system while the built-in encoding stays unchanged for generic clients.

The scene value model

An authored USD value is carried by UsdValue, a readonly struct that scopes a value to the shapes a .usda document can express. A Variant cannot stand in for it: the USD value model is recursive and ragged, with tuples (float3), arrays, arrays of tuples (color3f[]), matrices authored as a tuple of row tuples, and asset paths and prim path references that must round-trip as their own syntax.

UsdValue implements INullable, so an attribute with no authored value is UsdValue.Null — never UsdValue?. Values are read through TryGet* accessors; there is no boxing accessor:

UsdAttribute radius = prim.Attributes["radius"];

if (radius.Value.TryGetDouble(out double r))
{
    // a double3 or color3f arrives as a tuple instead
}

if (radius.Value.TryGetTuple(out ArrayOf<UsdValue> components))
{
    foreach (UsdValue component in components.Span)
    {
        component.TryGetNumber(out double v);
    }
}

Construction mirrors the authored syntax — UsdValue.From(1.5), UsdValue.FromToken("vertex"), UsdValue.FromAssetPath("./tool.usda"), UsdValue.FromTuple(...), UsdValue.FromArray(...). The attribute's TypeName stays authoritative for how a value is rendered back out, so the kind adds type safety without changing the emitted .usda.

The same type carries UsdAttribute.TimeSamples and UsdPrim.Metadata, and a nested metadata dictionary is a UsdValue of kind Dictionary.

An integral value that does not fit a signed 64 bit integer — a uint64 above long.MaxValue — has no integral kind to carry it, so it arrives as a Token holding its exact decimal digits rather than being wrapped into a negative Integer; the coercion layer reads that form back into a uint64.

Related packages

• Opc.Ua.OpenUsdScene.Server — materializes a scene into a server address space and exports it back
• Opc.Ua.OpenUsd — the Part 1 Bindings model
• Opc.Ua.OpenUsd.Client — the Part 1 connector

This package tracks a draft specification; the model URI, versions and NodeIds may change.

Namespace URI: http://opcfoundation.org/UA/OpenUSD/Scene/