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--- other:dsx:x4d:working_with_motion_capture_data [2024/07/16 17:01] – removed sgranger
+++ other:dsx:x4d:working_with_motion_capture_data [2025/06/19 19:59] (current) – Cleaned up and added section headers. wikisysop
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+====== Working with Motion Capture Data ======
+Surface-marker-based motion capture data for an x-ray trial can be used to calculate initial poses for the bones you want to track in the trial. To use this data in X4D, you must have [[visual3d:documentation:c3d_signal_types:c3d_format|C3D files]] with labelled marker trajectories for the motion trial and its associated static trial, and [[visual3d:visual3d_overview|Visual3D]] files defining a kinematic model and its motion constraints. Within the [[other:dsx:dsx_overview|DSX Suite]] this model is referred to as a //motion capture model//.
+===== Using Visual3D =====
+Creating the model template and the constraint scripts requires a good working knowledge of Visual3D.
+  - The [[visual3d:documentation:modeling:modeling_overview|model template file]] (MDH) defines the segments and landmarks in the kinematic model, based on a specific marker set.
+  - The [[visual3d:documentation:pipeline:pipeline_overview|build script]] (V3S) creates the constraints that define the relative motions of the segments in the model.
+  - The [[visual3d:documentation:pipeline:general_information:recalc_pipeline|recalc script]] (V3S) updates the segment poses to satisfy the constraints.
+===== Using Models within DSX =====
+Once the model is defined, and applied to a particular DSX trial, it can be used in three modes:
+  * **Marker Mode** The motions of the segments are driven by the surface markers, with constraints enforced. This mode is used to calculate mocap poses in X4D.
+  * **Interactive Mode** You can interactively change all of the model's degrees of freedom (the 6 degrees of freedom of the root segment, and the joint angles). Constraints are enforced. This mode is used when you manipulate the bone poses in X4D.
+  * **DSX Mode** The motions of the segments are driven by DSX tracking results (transform matrices). Constraints are not enforced. This mode is used when DSX results are viewed and analyzed in Visual3D.
+In addition to generating initial poses for the tracking objects, you can use the mocap model to help with manual positioning of the objects. In the [[Other:DSX:X4D:Motion_Capture_Model|Mocap Model]] widget in X4D, you can turn on the model's joint constraints, making it easier to move all of the objects together as a group, or to move them relative to each other in a realistic manner (e.g., flexing or twisting the vertebrae in a spine model).