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Focus3, Vive Pro Eye and SRanipal

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I work in a company that makes software for eye treatment. We have an application for Windows that uses the Eye Tracker from the HTC Vive Pro Eye to calculate the deviation of each eye separately.

Now we want to make that application usable by the new Focus 3 as well.

We have the development in Unity version 2021.1.24f1.

To collect the information of each eye we use SRanipal_Eye_API.GetEyeData(ref eyeData). The problem is that the Focus 3 does not receive any type of information using this method.

I have not been able to find an example programmed for the Focus 3 either.

Everything I find obtains information to obtain the gaze point at which the user looks, but we need to obtain the information of the eye pupils, since we need to detect deviations in the eyes that the patients who use the application may have.

How can we get that information in Focus 3? How can we make it still compatible with HTC Vive Pro Eye?

I would appreciate any information you can give me.

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I think I have solved my problem,

It seems that I had an incorrect installation of SRanipal. I was checking everything and I thought I had a compatible version because the Tobii VRU02 Runtime version was 1.16.36. However, the installation that I had of SRanipal was the old way, that is, I had installed HTC Vive Pro Eye on the one hand and SRanipal on the other using the following link: https://www.vive.com/us/support/vive-pro-eye/category_howto/installing-eye-tracking-software.html

I have uninstalled that version of SRanipal, I have downloaded the Pro Eye installer again and installed it. In this new process, SRanipal is automatically installed (not like before) and although I have installed the same version of Tobii VRU02 Runtime (1.16.36), it does connect correctly with both the Vive Pro Eye and the Focus 3, so I assume something changes from process to process.

If I find something else I will update this post, for now I think my query is resolved.


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  • 1 month later...

Hi @DiegoVisionary

I've been trying for about a week now to get the add-on Eye Tracker for HTC VIVE Focus 3 to work. First i wanted to use it on a project in Unity, but now I just want to try and get it to work on a 360-degree video/image and somehow get gazing data out of it. I spoke with Tobii support, but they said that they don't support the VIVE Focus 3. So did iMotions say.. Could you elaborate on what to do? 

I've tried to follow your link and download the SRanipalInstaller, but is says that can't open the "SRanipalService" as the file wasn't found..


Louis H

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  • 2 weeks later...

Hi @cluelou,

Sorry for taking so long to reply, but I occasionally log in to the forum and for some unknown reason I had notifications turned off and didn't see your message.

I managed to get SRanipal working in Unity3D and Focus3 by following these steps:

  1. First I installed SteamVR and VIVE Business Streaming on my PC (I assume you have already done these steps).
  2. Then I installed from the Steam shop, VIVE Console for SteamVR, it is a free application and among other things it installs the SRanipal software on your PC.  If you have a previous version of SRanipal installed on your PC following the link I mentioned in my previous post, uninstall it because that version will not work.
  3. Go to the VIVE development website and from there download the SRanipal SDK. https://developer-express.vive.com/resources/vive-sense/eye-and-facial-tracking-sdk/
  4. Import the SDK into Unity and check the documentation and especially the examples. There is not much documentation and it is very limited, but the examples are quite graphical.

By following the above steps you should be able to work with SRanipal. In Unity I am using the OpenXR library to support VR. You may need to load support for Focus 3 in Interaction Profiles, by loading Eye Gaze Interaction Profile and HTC Vive Focus3 Controller Support. Everything is explained in the following link: 



I hope this will help you to know where to start.


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