AR 內容的放置方式和大小必須正確，才能融入場景。虛擬物體就像真實世界中的物品一樣，遠一點的虛擬物件應較小。您可以執行命中測試 (或針對 Unity 的 AR Foundation 執行光柵)，確定 3D 物件的正確位置。正確放置方式可確保 AR 內容能以適當的大小 (透明) 顯示。
命中測試能夠找到現實世界 3D 幾何圖形與由起點和方向組成的虛擬光柵之間的交集。最常使用裝置相機做為來源的 Ray 應用程式，不過 ARCore 包含的 API 可用於以世界空間座標的任意光線執行命中測試。
假設有一條直線從使用者的裝置鏡頭往前延伸，直到達到場景的 3D 幾何圖形，例如地板、牆壁或物體。發生這種情況時，您會收到命中結果清單，或與偵測到的場景幾何圖形相交的交集清單。這份清單會根據與裝置之間的距離排序，最遠的十字路口。這點非常重要，因為一般情況下，您無法看到某些物件背後的物件，因此在多數情況下，第一個結果才是最重要的。
[null,null,["上次更新時間：2025-07-26 (世界標準時間)。"],[[["\u003cp\u003eARCore hit-tests, or raycasts, help you determine the correct placement and scale of virtual objects in the real world by finding intersections between a ray and the scene's geometry.\u003c/p\u003e\n"],["\u003cp\u003eHit results provide distance, pose, and trackable information, allowing you to realistically anchor 3D content.\u003c/p\u003e\n"],["\u003cp\u003eThere are four hit result types: Depth, Plane, Feature Point, and Instant Placement, each with different use cases and tradeoffs depending on the desired outcome and device capabilities.\u003c/p\u003e\n"],["\u003cp\u003eDepth hit results, available on Depth supported devices, utilize depth information for precise object placement on any surface, while Plane hit results are suitable for floors and walls.\u003c/p\u003e\n"],["\u003cp\u003eFeature Point hit results rely on visual features, and Instant Placement allows for fast content placement even with initially unknown depth and scale.\u003c/p\u003e\n"]]],[],null,["# Hit-tests place virtual objects in the real world\n\n**Platform-specific guides** \n\n### Android (Kotlin/Java)\n\n- [Developer guide](/ar/develop/java/hit-test/developer-guide)\n\n### Android NDK (C)\n\n- [Developer guide](/ar/develop/c/hit-test/developer-guide)\n\n### Unity (AR Foundation)\n\n- [Developer guide](/ar/develop/unity-arf/hit-test/developer-guide)\n\nYour browser does not support the video tag.\n\nAR content must be correctly placed and sized to blend into a scene. Like real-world objects, virtual objects that are further away should appear smaller. You can perform a **hit-test** (or a **raycast** in AR Foundation for Unity) to determine the correct placement of a 3D object in your scene. Correct placement ensures that the AR content is rendered at the appropriate (apparent) size.\n\nHit-tests find intersections between either real-world 3D geometry and a virtual ray consisting of an origin and direction. Rays with the device's camera as the origin are used most commonly, though ARCore includes an API for performing hit-tests with an arbitrary ray in world space coordinates.\n\nImagine that there is a ray originating from a user's device camera that extends forward until it hits the 3D geometry of the scene, such as a floor, wall, or object. Once this happens, you receive a list of **hit results**, or intersections with detected scene geometry. The list is sorted by distance from the device, with the nearest intersection first. This is important because generally you can't see objects occluded behind other objects, so most of the time the first result is the most significant.\n| **Note:** Hit-tests are typically performed as rays from the device or device camera, but it is possible to have an arbitrary ray origin and direction.\n\nContents of a hit result\n------------------------\n\nAn individual hit result is returned as a list with the following information for each result:\n\n- Distance from the ray origin, in meters\n- Pose (position and orientation) of the hit result\n- The 3D geometry that you hit, in the form of a Trackable\n\nYou can then use the desired hit result to [realistically place your 3D content using an Anchor](/ar/develop/anchors).\n\nHit result types\n----------------\n\nThere are four types of hit results: Depth, plane, feature point, and Instant Placement results. Each has its own use cases and tradeoffs, as shown by the following table.\n| **Note:** Depth hit results require [Depth supported devices](/ar/devices#google_play_devices). On non-Depth supported devices, Depth supported devices that do not have depth data yet or on sessions where Depth has been disabled, use plane hit results instead.\n\n| Hit result type | Description | Orientation | Use case |\n|----------------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|-------------------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|\n| Depth | Uses depth information from the entire scene to determine a point's correct depth and orientation | Perpendicular to the 3D surface | Place a virtual object on an arbitrary surface (not just on floors and walls) |\n| Plane | Hits horizontal and/or vertical surfaces to determine a point's correct depth and orientation | Perpendicular to the 3D surface | Place an object on a plane (floor or wall) using the plane's full geometry. Need correct scale immediately. Fallback for the Depth hit-test |\n| Feature point | Relies on visual features around the point of a user tap to determine a point's correct position and orientation | Perpendicular to the 3D surface | Place an object on an arbitrary surface (not just on floors and walls) |\n| Instant Placement (Persistent Raycast) | Uses screen space to place content. Initially uses estimated depth provided by the app. Works instantly, but pose and actual depth will change once ARCore is able to determine actual scene geometry | +Y pointing up, opposite to gravity | Place an object on a plane (floor or wall) using the plane's full geometry where fast placement is critical, and the experience can tolerate unknown initial depth and scale |\n\nDevice compatibility\n--------------------\n\nHit-tests work on all [ARCore supported devices](/ar/devices), but Depth hit-tests will require [Depth supported devices](/ar/devices#google_play_devices).\n\nUse hit results to place AR content\n-----------------------------------\n\nOnce you have a hit result, you can use its pose as input to [place AR content](/ar/develop/anchors) in your scene."]]
