Image tracking

To use image tracking on ARCore, you must create a reference image library. See AR Foundation Image tracking for instructions.

When you build the Player for Android, the ARCore build code creates a imgdb file for each reference image library. ARCore creates these files in your project's StreamingAssets folder, in a subdirectory called HiddenARCore, so Unity can access them at runtime.

You can use .jpg or .png files as AR reference images in ARCore. If a reference image in the XRReferenceImageLibrary isn't a .jpg or .png, the ARCore build processor attempts to convert the Texture to a .png so that ARCore can use it.

When you export a Texture2D to .png, it can fail if the Texture's Texture Import Settings have Read/Write Enabled disabled and Compression is set to None.

To use the Texture at runtime (not as a source Asset for the reference image), create a separate .jpg or .png copy for the source Asset. This reduces the performance impact of the Texture Import Settings at runtime.

Reference image dimensions

To improve image detection in ARCore you can specify the image dimensions. When you specify the dimensions for a reference image, ARCore receives the image's width, and then determines the height from the image's aspect ratio.