DIY Eye and Face Tracking for the Valve Index: EyeTrackVR, Project Babble and Setup Guide

Yes—you can add eye gaze, blinking and lower-face expression tracking to a Valve Index without replacing the headset. The practical solution is modular: EyeTrackVR handles eye tracking, Project Babble handles lower-face movement, and software such as Baballonia and VRCFaceTracking sends the resulting data to VRChat, Resonite or ChilloutVR. This is an add-on system, not native Valve firmware support, so expect 3D-printed mounts, extra USB hardware, calibration and troubleshooting.

What you are actually adding

“Eye and face tracking” describes several different signals. Keeping them separate makes the build and your expectations much clearer.

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• Eye gaze: the direction each eye is looking.
• Eye actions: blinks, eyelid openness and related eye parameters.
• Lower-face tracking: mouth opening, smiling, cheek and jaw movement, and lip shapes.

EyeTrackVR is the DIY eye-tracking component. Project Babble is primarily a lower-face expression tracker, not a complete eye tracker. A combined build can provide a convincing eye-and-mouth avatar, but it should not be described as one unified sensor or guaranteed full-face capture.

The Index remains a normal SteamVR headset. The added cameras and microcontrollers run as separate USB or network devices and feed tracking data through OSC or an integration layer.

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The recommended software and hardware stack

Baballonia’s current documentation describes VRChat support through VRCFaceTracking and the VRCFT-Babble module, native Resonite support, and a mod-based ChilloutVR route. Its Steam page is Project Babble Baballonia. Support is strongest in these social-VR applications; arbitrary SteamVR games may not expose avatar parameters or an interface for the data.

What you need

EyeTrackVR parts

• Two supported ESP32 camera boards. The current V4 path recommends two XIAO ESP32-S3 Sense modules.
• Two cameras without infrared filters. The parts guide identifies 130-degree no-IR cameras as a recommended option.
• An EyeTrackVR infrared-emitter kit or a documented equivalent.
• A USB hub for a wired Index build, preferably with enough ports for both eye cameras, the LED hardware and any face tracker.
• Short USB-C data cables or the adapters required by your boards.
• Index-specific 3D-printed mounts, camera extensions, wires and connectors as required by the chosen design.

Some inexpensive camera modules arrive with an IR-cut filter that must be removed by hand. That operation can damage the module or introduce dust, so follow the instructions for the exact camera rather than assuming every board is prepared the same way. The live parts list is EyeTrackVR’s parts documentation; the V4 build page is the V4 full-build guide.

Project Babble parts

Babble requires one or more compatible cameras, a mount that keeps the mouth and lower face visible, a computer to run the tracker, and an integration into your target application. Its hardware designs change, so the official documentation should be treated as the current bill of materials rather than a frozen list. Start at the Babble introduction and the ProjectBabble repository. Official or prebuilt hardware is also presented at babble.diy.

Representative EyeTrackVR component costs

The parts documentation gave these example signals, not a guaranteed project total:

Printing, tools, shipping, tax, spare components and failed parts are additional. On August 16, 2026, the EyeTrackVR store showed a V4 mini No-Solder LED Kit at $37.99 (sold out), a V4 Lite DIY LED Kit at a $9.99 sale price, replacement wire pairs at $3.50 and ESP camera cable extensions at $4.99. These are time-specific listings; check the store before buying.

Choose a Valve Index mounting design

Lens-mounted brackets

Lens clips place cameras and emitters close to the eyes and avoid replacing the frunk. They can look tidy, but clearance is tight: an incorrectly positioned bracket can reduce eye relief, touch the facial interface or shift when the strap is tightened. Wires may need extensions, and some mounts call for adhesive.

Replacement or modified frunk

A replacement “DEV Frunk” style arrangement provides more room for boards, a hub and face-tracking hardware, with easier cable access. It requires more fabrication and can alter weight, ventilation and reversibility. Removing or cutting the original shell is a permanent-risk choice.

Compact hub or community mounts

The Index guide also describes a compact Gumstick USB Hub Dongle approach and lists community mounts. Use Index-specific designs rather than a generic VR mount: the camera field of view, lens clearance, emitter position, facial-gasket fit, cable bend radius and frunk access all matter. See the Valve Index guide.

Start reversibly with printed clips, an external bracket, a replacement panel, Velcro or mechanical fasteners. Avoid hot-gluing boards, drilling the shell or routing wires through the gasket until the cameras work and the fit is comfortable. If adhesive is required, the V4 guide advises gluing the plastic housing—not the lens or optical assembly.

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Build EyeTrackVR first

1. Test every component. Connect each camera board directly, confirm that the ESP32 boards enumerate, inspect LED wiring and verify that the mount clears the lenses and facial interface. Keep a spare camera or board if disassembly will be difficult.
2. Prepare the cameras. Use no-IR-filter modules or perform the exact filter-removal procedure for your model. Protect the sensor and lens from dust.
3. Flash the firmware. The current V4 path uses OpenIris firmware on supported ESP32 camera boards. In Windows Device Manager, identify each serial device; an example port might be COM4, but your number will differ. Unplug one board at a time to map the left and right devices. Wireless setups instead use configured mDNS names such as ETVR-left.local.
4. Assemble the optical hardware. Fit the emitters around the lens openings, mount each camera so it sees its corresponding eye, install extensions where the Index design requires them, and secure the boards and cables.
5. Install the hub. A typical wired layout uses the Index USB connection, a compact hub, one connection per ESP32 board and one for the IR LED board. Leave a port for a separate face tracker. The parts guide recommends at least four ports for a combined build and notes that an MTT-capable hub may be needed when a Vive Facial Tracker shares the connection.
6. Configure the application. Select the camera inputs or COM ports, confirm both eye images, check left/right orientation, verify that IR illumination is visible to the cameras and make sure the facial gasket does not block the view. EyeTrackVR is actively developed, so labels and screens can change; use the current software guide at the documentation home.
7. Calibrate while wearing the headset normally. Set lens spacing, strap tension, eye relief and facial-interface position first. Moving the headset, changing camera angle or altering the camera-to-eye distance can reduce accuracy and require recalibration.

EyeTrackVR documents OSC-triggered actions. It listens on OSC port 9001; send a Boolean True to /avatar/parameters/etvr_recenter or /avatar/parameters/etvr_recalibrate. The corresponding parameter names are etvr_recenter and etvr_recalibrate. The wired configuration is documented as reaching up to roughly 70 FPS; that is a project figure, not a guaranteed end-to-end avatar update rate.

Add Project Babble after the eyes work

Install the face camera only after EyeTrackVR is stable. This separates camera, hub, OSC and avatar problems instead of creating one large debugging exercise.

• Place the camera so it sees the mouth, cheeks and jaw without the Index gasket, nose area, microphone or cable loop blocking it.
• Secure the mount so tightening the head strap does not change the camera angle.
• Set exposure and lighting so the lower face remains visible; masks, heavy facial hair and strong shadows can reduce usable detail.
• Run Babble and verify expression output before connecting it to the avatar.

Babble models and integrations are still evolving. Use its current troubleshooting material rather than treating one camera or mount as permanently authoritative.

Connect the trackers to VRChat

1. Install VRCFaceTracking through Steam.
2. Install the VRCFT-Babble module described by Baballonia.
3. Run Baballonia and choose the module mode for eyes, face or both.
4. Restart VRCFaceTracking if the current module instructions require it.
5. Load an avatar that exposes compatible eye-look and lower-face parameters.

A working camera pipeline does not guarantee visible avatar movement. The application must receive the data, the module must be active, and the avatar must contain the relevant parameters or blendshapes. VRChat’s native eye-look option can provide eye movement by itself, but it does not replace lower-face tracking.

Wired or wireless EyeTrackVR?

For Index owners who already use Vive or Tundra wireless trackers, begin with wired EyeTrackVR unless cable simplicity matters more than radio reliability.

Troubleshooting by symptom

Safety, comfort and reversibility

Infrared light is invisible, so do not judge emitter brightness by eye. Follow EyeTrackVR’s documented design and safety guidance at the photobiological-safety document; do not increase LED power or substitute unverified emitters.

Additional boards, hubs and cables can make the Index front-heavy, hotter or less comfortable. The DEV Frunk’s open design is presented as a ventilation consideration, not a universal thermal guarantee. Stop and redesign if the gasket is pressed, the lens view is obstructed, cables snag or the mount shifts during use.

Which route makes sense?

No route is universally best. The Index is a strong platform for a wired maker build because it is already tethered and has USB near the headset, but the project remains active development: EyeTrackVR labels its V4 guide unfinished, and Babble warns that documentation can become outdated. Treat the live project pages as the authority for firmware, mounts and module versions.

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Inter-pupillary Distance (IPD) - 58mm - 70mm range physical adjustment; Optics - Double element, canted lens design

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Useful project links

• EyeTrackVR Valve Index guide
• EyeTrackVR parts list
• EyeTrackVR V4 build
• Baballonia repository and compatibility details
• Project Babble documentation
• EyeTrackVR component store

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