Vicon Nexus — Motion Capture & Clinical Gait Analysis Software for Biomechanics

Vicon Nexus is the industry's most widely adopted software platform for clinical gait analysis, biomechanical research, sports science, and rehabilitation motion capture. The Vicon Nexus application connects to, controls, calibrates, collects, and processes data from Vicon 3D motion systems. The software also allows the integration and synchronized capture from video cameras and other pieces of scientific equipment used in clinical gait analysis and sport biomechanics. These devices include force platforms, EMG systems, accelerators, and other measurement devices common in hospital and university laboratories.

What Vicon Nexus Delivers — The Complete Motion Capture Workflow

The Nexus workflow manages the complete journey from laboratory setup through to clinical report generation:

Camera calibration — Nexus requires periodic calibration to precisely determine where the cameras are positioned in space. A wand having reflective spheres set at known distances is waved throughout the movement space. Nexus then computes the camera positions, orientations, and lens parameters. Real-time calibration feedback confirms camera accuracy throughout the calibration sequence, ensuring consistent, reproducible data standards across sessions and over time. 
Subject preparation and marker labelling — A patient profile is created in Nexus and the appropriate biomechanical model selected. Markers are placed on anatomical landmarks per the model protocol, and a static subject calibration trial defines segment orientations and joint centre positions.
Multi-device data collection — Cameras capture three-dimensional marker trajectories simultaneously with force plate ground reaction forces, EMG muscle activity, video reference footage, and any additional analogue device signals — all time-synchronised through Nexus.
Real-time processing and visualisation — Vicon's Nexus software can work in real time, permitting immediate visualization of data, or in offline mode, recording the movement for later analysis. It has been designed to display data as they are collected: 3-D marker data, analog data, and reference video images, as well as the current system status. The operator can view reconstructed data in a 3-D workspace as the motion occurs, or view stored motions for review purposes.
Biomechanical model processing — Once you collect your walking trials, Nexus runs the biomechanical model pipeline automatically, calculating joint angles, moments, and powers across the full gait cycle. You review each trial's waveforms in the graphing panel, checking for marker dropout, asymmetrical force plate strikes, and any spikes that suggest a bad step. xft-china
Report generation — Processed data is exported through Nexus Insight or Polygon for clinical report generation, or to external analysis software for research pipelines.

Plug-In Gait (PiG) & CGM2 — Concurrent Biomechanical Models 

Use native PiG and CGM2 models that can run concurrently to compare datasets. 

Nexus natively supports two of the most widely used clinical biomechanical models:

Plug-In Gait (PiG) — Vicon's proprietary implementation of the conventional gait model, first introduced in the 1980s and refined over four decades of clinical and research use. PiG is the most widely used clinical gait model globally — providing the standardised, normative-referenced kinematic and kinetic outputs (joint angles, moments, and powers at the hip, knee, and ankle) that are the foundation of clinical gait interpretation in the majority of hospital gait laboratories worldwide.

Conventional Gait Model 2 (CGM2) — An updated, open-source validated evolution of the conventional gait model incorporating methodological improvements in joint centre estimation, segment definition, and kinematic calculation. CGM2 addresses specific limitations of the original PiG model that have been identified in the clinical and research literature — providing improved accuracy and inter-laboratory reproducibility.

Running PiG and CGM2 concurrently on the same trial dataset enables direct, paired comparison of the two models' outputs — supporting transition from PiG to CGM2 in established clinical programmes while maintaining continuity of historical datasets, and enabling research investigations into model-specific measurement differences.