PDG

PDG

PDG(Procedural Dependency Graph)
TOPS(Task Operators)

PDG is designed to:
•Describe complex dependencies visually with nodes
•Transform that dependency description into a set of actionable, monitorable tasks
•Distribute those tasks with the help of a scheduler and compute them in parallel

为什么设计PDG：

• 直观的描述依赖关系
• 将该依赖关系描述转换为一组可操作的，可监视的任务
• 在调度程序的帮助下分发这些任务并并行计算它们

PDG=所有的任务及其中蕴含的依赖关系。是高于OBJ、ROP、SHOP、CHOP等层面的，由此诞生了一个崭新的模块——TOP（Task OP）。PDG是一个独立的API接口，而TOP是类比传统SOP、DOP等模块的一套节点系统。Houdini 17.5包含所有的PDG和TOP。

TOPS

A TOP network describes a “recipe” for generating work items for the computer to do, and efficiently runs them in processes on a single machine, or on a render farm, figuring out dependencies so it can run as many items in parallel as possible. The generated “recipe” is an underlying PDG (Procedural Dependency Graph) describing the work items to do and their dependencies.

TOP网络描述了一个“recipe”，用于生成计算机要执行的工作项，并在单个计算机或渲染服务器场中的进程中有效地运行它们，计算出依赖关系，以便它可以尽可能多地并行运行项目。 生成的“recipe”是底层PDG（程序依赖关系图），描述要执行的工作项及其依赖关系。
参考

1. SideFX Releases New Procedural Dependency Graph Technology[2019.3]
2. Introduction to TOPs[2019.9]
3. PDG到底是啥玩意[2019.3]