Barracuda PoseNet Tutorial Pt. 2.5 (Outdated)

This post covers how to view preprocessed images during runtime.

Christian Mills


November 5, 2020

Version 2: Part 1

Last Updated: Nov 30, 2020

Previous: Part 2


Examining the preprocessed input images can be a useful step when debugging. We can see how much the source image gets squished when resized to a square aspect ratio. The model can have a hard time accurately determining key point locations if the individual gets squished too much. We can also get a visual sense of how the preprocessing operations change the pixel values.

Make a New Screen

We can make a second screen to see what the preprocessed images look like before they get fed into the model.

Make a Quad

In the Hierarchy tab, make an new Quad and name it InputScreen.

Set the Scale

We’ll set both the X and Y scale values to 360 to match our current input resolution for the model.

Set the Position

We also need to set the X and Y position values to 180. Set the Z position value to -1 so that it’s in front of the VideoScreen.

Make a RenderTexture

Make another RenderTexture and name it input_texture.

Set the Size

Set the Size to 360 x 360.

Apply the input_texture

Drag and drop the input_texture onto the InputScreen in the Scene tab.

Make the Shader Unlit

Set the Shader for the InputScreen to Unlit/Texture just like the VideoScreen.

Update the PoseNet Script

Next, we need to create a few new public variables in the PoseNet script.

Add displayInput variable

Create a new public bool variable called displayInput. This will add a checkbox in the Inpsector tab that we can use to turn the InputScreen on and off.

Add inputScreen variable

Create a new public GameObject variable called inputScreen. We need to access the InputScreen object to activate and deactivate it.

Add inputTexture variable

Create a new public RenderTexture variable called inputTexture. We’ll assign the input_texture asset to this variable in the Unity Editor.

Modify the Update() Method

We can use the Graphics.Blit() method to copy the processedImage data to the inputTexture variable. We’ll use the inputScreen.SetActive() method to activate and deactivate the InputScreen.

Assign Inspector Variables

With the PoseEstimator selected in the Hierarchy tab, drag and drop the InputScreen and input_texture into their respective variables in the Inspector tab.

Test the New Screen

Make sure the Display Input checkbox is ticked in the Inspector tab. It will be easier to see the changes to the preprocessed images if we use a full color video. We can set the Video Clip for the Video Player to the pexels_woman_dancing file that we downloaded in Part 1.

Rescale Pixel Values

The current result may not be the most accurate representation as pixel values are still in the the range of [0, 255] instead of Unity’s [0.0, 1.0]. We can rescale the pixel values by adding another function to our PoseNetShader.

Update PoseNetShader

We’ll create another function called ScaleInputImage() that divides the RGB channel values by 255.0.

Note: Rescaling the pixel values will have a small impact on performance. Make sure to untick the Display Input checkbox when you’re not examining the input image.

Create ScaleInputImage Method

We need to create a new method in the PoseNet script to execute the function just like for the PreprocessResNet function.

Call ScaleInputImage Method

Finally, we’ll call the new method in the if (displayInput) statement.



We now have a little screen that we can use to view the processed input image before it gets fed to the model.

GitHub Repository - Version 1

Next: Part 3