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Holographic face tracking sample

Shows how to acquire video frames from the photo/video (PV) camera and use the FaceAnalysis API to determine if there are any faces in front of the HoloLens. We display a cube on top of the detected face and a video stream inside the user's view.

Note: This sample is part of a large collection of UWP feature samples. If you are unfamiliar with Git and GitHub, you can download the entire collection as a ZIP file, but be sure to unzip everything to access shared dependencies. For more info on working with the ZIP file, the samples collection, and GitHub, see Get the UWP samples from GitHub. For more samples, see the Samples portal on the Windows Dev Center.

If multiple faces are detected, then the sample will pick the face closest to the center of the user's gaze. If no faces are detected then the text "No faces detected" is displayed.

This sample uses the webcam and microphone app capability in order to access the MediaCapture object and stream video images to the FaceAnalysis API and to the user.

FaceAnalysis and HoloLens

The FaceTracker class processes images and returns a list of rectangles inside the image where the faces are detected. This is a very intensive process to run in real-time, and could reduce rendering performance if it were to slow down the main render thread. It is very important that Holographic applications maintain 60fps for rendering to reduce user discomfort.

In this sample, we are rendering holograms at 60fps, receiving video frames at 30fps, and running the FaceTracker as fast as it can process new frames (about 10-15fps). In order to keep rendering performance at 60fps, we run the FaceAnalysis on an explicit background thread. This adds a bit of complexity to sychronize between the FaceAnalysis worker thread and the main render thread.

Handling NV12 images

The HoloLens PV camera provides NV12 video images by default, which can't be directly used in the shaders for rendering to a RGB backbuffer. Converting the full image from NV12 to RGB is possible, but it's an expensive operation. We only need to render the portion of the frame where the face was detected. So instead of converting the full image, we can convert NV12 to RGB in the pixel shader itself.

NV12 is a 8-bit YUV format for video rendering. To obtain more information about YUV and video formats, see Recommended 8-Bit YUV Formats for Video Rendering.

Additional remarks

Note The Windows universal samples for Windows 10 Holographic require Visual Studio 2017 Update 3 to build, and a Windows Holographic device to execute. Windows Holographic devices include the Microsoft HoloLens and the Microsoft HoloLens Emulator.

To obtain information about Windows 10 development, go to the Windows Dev Center.

To obtain information about the tools used for Windows Holographic development, including Microsoft Visual Studio 2017 Update 3 and the Microsoft HoloLens Emulator, go to Install the tools.

Related topics

Samples

BasicFaceDetection

BasicFaceTracking

CameraFrames

Reference

The following types are used in this code sample:

System requirements

Client: Windows 10 Holographic build 14393

Phone: Not supported

Build the sample

  1. If you download the samples ZIP, be sure to unzip the entire archive, not just the folder with the sample you want to build.
  2. Start Microsoft Visual Studio 2017 and select File > Open > Project/Solution.
  3. Starting in the folder where you unzipped the samples, go to the Samples subfolder, then the subfolder for this specific sample, then the subfolder for your preferred language (C++, C#, or JavaScript). Double-click the Visual Studio Solution (.sln) file.
  4. Press Ctrl+Shift+B, or select Build > Build Solution.

Run the sample

The next steps depend on whether you just want to deploy the sample or you want to both deploy and run it.

Deploying the sample to the Microsoft HoloLens emulator

  • Click the debug target drop-down, and select Microsoft HoloLens Emulator.
  • Select Build > Deploy Solution.

Deploying the sample to a Microsoft HoloLens

  • Developer unlock your Microsoft HoloLens. For instructions, go to [Enable your device for development] (https://msdn.microsoft.com/windows/uwp/get-started/enable-your-device-for-development#enable-your-windows-10-devices).
  • Find the IP address of your Microsoft HoloLens. The IP address can be found in Settings > Network & Internet > Wi-Fi > Advanced options. Or, you can ask Cortana for this information by saying: "Hey Cortana, what's my IP address?"
  • Right-click on your project in Visual Studio, and then select Properties.
  • In the Debugging pane, click the drop-down and select Remote Machine.
  • Enter the IP address of your Microsoft HoloLens into the field labelled Machine Name.
  • Click OK.
  • Select Build > Deploy Solution.

Pairing your developer-unlocked Microsoft HoloLens with Visual Studio

The first time you deploy from your development PC to your developer-unlocked Microsoft HoloLens, you will need to use a PIN to pair your PC with the Microsoft HoloLens.

  • When you select Build > Deploy Solution, a dialog box will appear for Visual Studio to accept the PIN.
  • On your Microsoft HoloLens, go to Settings > Update > For developers, and click on Pair.
  • Type the PIN displayed by your Microsoft HoloLens into the Visual Studio dialog box and click OK.
  • On your Microsoft HoloLens, select Done to accept the pairing.
  • The solution will then start to deploy.

Deploying and running the sample

  • To debug the sample and then run it, follow the steps listed above to connect your developer-unlocked Microsoft HoloLens, then press F5 or select Debug > Start Debugging. To run the sample without debugging, press Ctrl+F5 or select Debug > Start Without Debugging.