ARAnchor 和 AnchorEntity 有什么区别? [英] What's the difference between ARAnchor and AnchorEntity?

问题描述

我目前正在用 RealityKit 做一些实验.

I'm currently doing some experiments with RealityKit.

我一直在查看一些示例代码，我对 ARAnchor 和 AnchorEntity 之间的区别以及何时使用一个而不是另一个感到有些困惑.

I've been looking at some sample code, and I'm a bit confused about the differences between ARAnchor and AnchorEntity, and when to use one over the other.

到目前为止我知道:

• 两者都是描述现实世界中位置的锚点.
• AnchorEntity 还可以将其他 Entity 作为子项，因此您可以将模型对象直接添加到锚点.你不能用 ARAnchor 做到这一点，你必须手动"将模型对象添加到 rootNode，并正确使用锚点的位置.莉>
• 在文档中，它说 ARKit 使用添加的 ARAnchor 来优化锚点周围区域的跟踪.AnchorEntity 的文档没有指定这一点.

• Both are anchors that describes a position in the real world.
• AnchorEntity can also have other Entity's as children, so you can add model objects directly to the anchor. You can't do this with ARAnchor, you have to add model objects "manually" to the rootNode, and use the position of the anchor the place it correctly.
• In the documentation it says that ARKit uses the added ARAnchor to optimize the tracking in the area around the anchor. The documentation for AnchorEntity does not specify this.

现在我将 AnchorEntity 作为根节点"添加到会话中，因为它更易于使用，因此我可以简单地将模型作为子项直接添加到此锚点.但随后我还向场景的锚点添加了位于相同位置的 ARAnchor，以增强围绕该点的跟踪.这是必要的吗?

Right now I add a AnchorEntity to the session as a "root node", since it's simpler to use, so that I can simply add models as children directly to this anchor. But then I also add a ARAnchor, located at the same position, to the scene's anchors, to enhance tracking around this point. Is this nececary?

推荐答案

更新时间:2021 年 4 月 3 日.

ARAnchor 类和 AnchorEntity 类都是为了同一个神圣的目的而创建的——连接 3D 内容到您的真实世界对象.

ARAnchor class and AnchorEntity class were both made for the same divine purpose – to tether a 3D content to your real-world objects.

RealityKit AnchorEntity 极大地扩展了 ARKit ARAnchor 的功能.这两者之间最重要的区别是 AnchorEntity 自动跟踪现实世界的目标，但 ARAnchor 需要 renderer(...) 或 >session(...) 实例方法来实现这一点.还要考虑到 ARAnchors 的集合存储在 ARSession 中，而 AnchorEntities 的集合存储在 Scene 中.

RealityKit AnchorEntity greatly extends the capabilities of ARKit ARAnchor. The most important difference between these two is that AnchorEntity automatically tracks a real world target, but ARAnchor needs renderer(...) or session(...) instance methods to accomplish this. Also take into consideration that the collection of ARAnchors is stored in the ARSession and the collection of AnchorEntities is stored in the Scene.

以下是层次差异:

RealityKit 的主要优点是能够同时使用不同的 AnchorEntities，例如 .plane、.image 和 .object.

The main advantage of RealityKit is the ability to use different AnchorEntities at the same time, such as .plane, .image and .object.

在 ARKit 中，如您所知，您只能在当前会话中运行一个配置:World、Image 或 Object.然而，ARKit 中有一个例外——你可以同时运行两个配置——WorldTracking 和 FaceTracking(但第一个必须是驱动程序，另一个必须是 驱动).

In ARKit, as you know, you can run just one config in the current session: World, Image, or Object. There is an exception in ARKit, however - you can run two configs together - WorldTracking and FaceTracking (but first one has to be a driver, and the other one – driven).

Apple 开发者文档说:

Apple Developer documentation says:

在 RealityKit 框架中，您使用 AnchorEntity 实例作为实体层次结构的根，并将其添加到场景的 anchors 集合实例.这使得 ARKit 能够将锚实体及其所有层次结构的后代放置到现实世界中.除了锚实体从Entity类继承的组件外，锚实体还符合HasAnchoring协议，赋予它一个AnchoringComponent实例.

In RealityKit framework you use an AnchorEntity instance as the root of an entity hierarchy, and add it to the anchors collection for a Scene instance. This enables ARKit to place the anchor entity, along with all of its hierarchical descendants, into the real world. In addition to the components the anchor entity inherits from the Entity class, the anchor entity also conforms to the HasAnchoring protocol, giving it an AnchoringComponent instance.

AnchorEntity 具有三个构建块:

• 变换组件(包含平移、旋转和缩放的变换矩阵)
• 同步组件(用于多用户体验的实体同步数据)
• 锚定组件(允许选择锚的类型——world、body 或 image)

所有实体都有同步组件，有助于组织协作会话.

All entities have Synchronization component that helps organise collaborative sessions.

AnchorEntity 有九种特定的锚点类型，用于九种不同的目的:

AnchorEntity has nine specific anchor types for nine different purposes:

• ARAnchor
  • 帮助实现 10 个 ARKit 锚点，包括 ARGeoAnchor 和 ARAppClipCodeAnchor

  
  您可以在您的应用中同时使用 ARAnchor 和 AnchorEntity 这两个类.或者你可以只使用 AnchorEntity 类，因为它足够了.

  
  You can simultaneously use both classes ARAnchor and AnchorEntity in your app. Or you can use just AnchorEntity class because it's all-sufficient one.

  有关ARAnchor 和AnchorEntity 的更多信息，请查看这篇文章.

  For additional info about ARAnchor and AnchorEntity, please look at THIS POST.

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