To achieve that, there were a series of challenges that needed to be addressed. The following list provides a description of each of those challenges, the solution we used and some alternatives.

• 3D environment: We wanted to create a simple Gym environment where both instructor and participants would be located, during the exercise class. For this job we chose Unity.
• Tracking and rendering instructor's movements: We needed to be able to render the trainer’s avatar inside the Gym and change the body position accordingly to the movements captured by the trainer’s cellphone camera. To help us with that we used MediaPipe an open-source cross-platform customizable Machine Learning solution. To integrate MediaPipe inside Unity we used an open-source plugin. Although the plugin facilitates the job, we encountered some issues regarding correctly tracking the instructor's movements.
• Handling session between instructor and participants: We started evaluating the possibility to use WebRTC to transmit the 3D instructor and virtual room to the participants’ application. Unity has an open-source library called Unity Render Streaming that allows that, including the possibility for the clients to interact with the rendering scene. 
• Spatial Voice Chat: Spatial Voice chat not only allows users to chat with each other within the application or game but also takes into consideration the user’s location, changing sound direction and volume accordingly. We wanted to incorporate this functionality in the application as it is an important factor for the user’s immersive experience inside our environment.