===== Model Builder Mode =====

Visual3D's Models tab allows user to build and modify custom models for marker-based motion capture data and to inspect the models that have been automatically built for markerless motion capture data and certain Inertial Measurement Units. In this view, the model appears in the right panel, with model building tools shown in the left panel.

{{:models1.png?1250}}

Building your biomechanical model is VERY important as it is the foundation for the rest of your analysis. Your model is used in conjunction with your [[Visual3D:Documentation:Definitions:Static_Trial|static trial]] (for marker-based motion capture) to tell Visual3D how it should interpret the dynamic motion trials during analysis, with any model able to be saved as a [[Visual3D:Documentation:Modeling:Model_Templates|model template]].

Details on the modelling process can be found in our [[Visual3D:Documentation:Modeling:Modeling_Overview|overview]] while each of the tab's four sections are described below.

==== Segments ====

A Visual3D model consists of a set of rigid segments, each of which corresponds to a body segment (major bone structure) of the subject whose motion is under study. The [[Visual3D:Documentation:Modeling:Segments:Segment_Overview|Segments]] section of the Model tab allows users to define and modify segment definitions including [[Visual3D:Documentation:Modeling:Segments:Segment_Properties|segment properties]] like mass, geometry, [[visual3d:documentation:modeling:segments:segment_inertia|inertial properties]], and [[visual3d:documentation:modeling:segments:animation_surface_models|animation styles]], and apply [[visual3d:documentation:kinematics_and_kinetics:inverse_kinematics|Inverse Kinematics constraints]].

==== Landmarks ====

[[Visual3D:Documentation:Modeling:Landmarks:Landmarks_Overview|Landmarks]] are virtual markers whose positions are computed automatically by Visual3D based on the positions of the actual markers, segments, or equations, according to rules which you define.

==== Muscles ====

Visual3D's modelling features allow users to define [[visual3d:documentation:modeling:muscles:muscles_overview|muscles]] as linear segments connecting a series of Landmarks. These muscles then need to be scaled in accordance with participant-specific features.

==== Subject Data / Metrics ====

Subject data and metrics are stored as [[Visual3D:Documentation:Modeling:Model_Metrics_|model metrics]] which are static values that can be used as parameters in the definition of segments and landmarks. These metrics include the MASS and HEIGHT of the subject, segment proximal and distal radius values that are computed during the construction of segments.