---
title: Preliminary_ReferenceImage
framework: usd
role: collectionGroup
path: usd/preliminary-referenceimage
---

# Preliminary_ReferenceImage

A schema that defines the properties of an image in the physical environment.

## Overview

Overview This schema defines the criteria that the runtime uses to recognize an image in the physical environment, including pixel data and width. When RealityKit opens a USDZ file that defines a reference image, it instantiates an AnchorEntity with a component type  AnchoringComponent.Target.image(group:name:). Declaration class Preliminary_ReferenceImage "Preliminary_ReferenceImage" (     inherits = </Typed> ) Define a reference image The following example defines a prim named ImageReference that instructs the runtime to scan for an image described by image.png. def Preliminary_ReferenceImage "ImageReference" {     uniform asset image = @image.png@     uniform double physicalWidth = 12 }

## Topics

### Properties

- [image](usd/image.md)
- [physicalWidth](usd/physicalwidth.md)

## See Also

### Anchoring

- [Placing a prim in the real world](usd/placing-a-prim-in-the-real-world.md)
- [Preliminary_AnchoringAPI](usd/preliminary-anchoringapi.md)