# Object detection

Drop one [`UObjectDetectionConsumer`](#uobjectdetectionconsumer) component on an actor and detected markers (colored ball/disc trackers) and 6-DoF objects spawn as child actors that follow the live AR 51 tracking feed. The owning actor's transform is the parent/anchor space for everything spawned.

:::caution[Units]
The AR 51 system reports **meters**; the consumer converts spawned actor transforms to Unreal **cm** internally. Fields that are *not* converted — notably `UTrackedInstance.Radius` and the smoothing thresholds — appear to be in **meters** as received; see per-field flags.
:::

## EInstanceType

Moved to [`EInstanceType`](/docs/sdk-api/unreal-api/classes/utrackedinstance#einstancetype).

## UTrackedInstance

Moved to [`UTrackedInstance`](/docs/sdk-api/unreal-api/classes/utrackedinstance).

## FMarkerItem

Moved to [`FMarkerItem`](/docs/sdk-api/unreal-api/classes/uobjectdetectionconsumer#fmarkeritem).

## UObjectDetectionConsumer

Moved to [`UObjectDetectionConsumer`](/docs/sdk-api/unreal-api/classes/uobjectdetectionconsumer).

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Next: [Hands, boundary & anchors](/docs/sdk-api/unreal-api/hands-boundary-anchors).