In one embodiment, a wearable apparatus is provided which may include a holographic film disposed on the wearable apparatus, an eye tracking device including an image sensor and an illuminator, and one or more processors. The processors may be configured to activate the illuminator to illuminate the holographic film and capture, with the image sensor, an image of at least a portion of the holographic film while the holographic film is illuminated. The processors may also be configured to determine a characteristic of the holographic film based on the image and determine, based on the characteristic, a location or an orientation of the image sensor relative to the holographic film. The processors may further be configured to change, based on the location or the orientation of the image sensor relative to the holographic film, at least one calibration parameter of the image sensor.