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--- visual3d:documentation:definitions:multisubject [2024/07/03 17:27] – removed sgranger
+++ visual3d:documentation:definitions:multisubject [2025/04/30 14:14] (current) – wikisysop
@@ Line 1: / Line 1: @@
+===== Multisubject =====
+Support for multisubject C3D files allows users to easily work with datasets that include more than one subject in a dynamic trial, for example, two people sparring or dancing within the capture volume. It's expected that subject prefixes are used in the C3D files. For example, a target is named "S001:LMK" where "S001:" is the subject prefix and "LMK" is the target name (note: most camera manufacturers already support this option).
+For the static trial, the multiple subjects can be in the same C3D file, or in multiple static C3D files.
+==== Notes ====
+  * If only collecting data with one subject in the volume, nothing about your processing procedure should change and you should not export C3D files with subject prefixes from your camera manufacturer.
+  * If you had a subject in one static trial, and a bench in another static trial. The two static trials can be associated and the segments in both trials will be created in the dynamic trials. [[Visual3D:Documentation:Definitions:Multistatic|If you are collecting data for one subject with multiple static trials, go here for more information]].
+  * This documentation refers mostly using the multi-subject workspace with two subjects, however, you can use as many subjects as you would like.
+==== Important Terms ====
+**[[visual3d:documentation:definitions:subject_prefixes|Subject Prefix]]**: In the C3D file, there is a parameter to specify the subject prefix. This should be specified by your motion capture system. Subject prefixes can be different from C3D file to C3D file
+{{:C3DSubjectPrefixes.png}}
+**[[visual3d:documentation:definitions:subject_tags|Subject Tag]]**: A subject tag associates a generic name to a subject prefix, for example "Ball-carrier" or "Tackler". The active Subject Tag can be set using the [[visual3d:documentation:pipeline:file_commands:select_active_file|Select_Active_File]] pipeline command.
+{{:SubjectTags.png}}
+==== Model Tab ====
+Within the [[visual3d:documentation:definitions:model_builder_mode|Model Builder tab]] the user can choose between the following options for active subject: ALL_SUBJECTS, NO_SUBJECT, and any individual subject prefix.
+{{:multisb.png}}
+^ Selection ^ Description ^
+| ALL_SUBJECTS | Allows you to view all segments with subject prefixes |
+| NO_SUBJECT | Allows you to view all segments not associated with a subject prefix (ex. LAB) |
+| Subject prefixes | Allows you to view all segments associated with that subject prefix. |
+==== Pipeline ====
+The first step to writing a pipeline is to assign a subject tag to a subject prefix using the [[Visual3D:Documentation:Pipeline:Model_Commands:Set_Subject_Tag|Set_Subject_Tag]] command. This is important since a subject prefix can be different for each data collection (ex. "S001:", "S002:"). The subject tag should be something general (ex. "Pitcher", "Catcher"). Once the subject tags have been defined, you can use the subject tags the same as you would a file tag using the [[Visual3D:Documentation:Pipeline:File_Commands:Select_Active_File#Subject_Tags|Select Active File]] command.
+As with single subject files, the resulting pipeline commands will work on the active subject tags that were specified in the Select Active File command
+=== Important Pipeline Commands ===
+Pipeline commands that are specifically important for multi-subject data or have been modified for this new feature include:
+  * [[Visual3D:Documentation:Pipeline:Model_Commands:Set_Subject_Tag|Set_Subject_Tag]]: Sets subject tags for specific files
+  * [[Visual3D:Documentation:Pipeline:File_Commands:Select_Active_File#Subject_Tags|Select_Active_File]]: Use subject tags to precisely specify your active files
+  * [[Visual3D:Documentation:Pipeline:File_Commands:Modify_C3D_Subjects_Parameters|Modify_C3D_Subjects_Parameters]]: Modify the parameters in the SUBJECTS group in the c3d file
+==== Examples ====
+=== Example 1: Building Multi-subject Models ===
+The compute model-based command works the same for multiple subjects as it always has for single subjects, but now also allows the customer to use [[Visual3D:Documentation:Definitions:Subject_Tags|Subject_Tags]] to identify when signals should be calculated for every subject in the model, between subjects, etc.
+Note: Segment A and Segment B tag refer to the Segment tag, or Reference Segment or Resolution Coordinate System.
+**Case 1:** Signal created for all subjects. Ex. RKneeAngle
+  * Subject tag: ALL_SUBJECTS
+  * Segment A Tag: ALL_SUBJECTS
+  * Segment B Tag: ALL_SUBJECTS
+**Case 2:** Signal created for all subjects relative to a segment that is only created in NO_SUBECT (ex. subject's foot relative to generic segment BOX).
+  * Subject tag: ALL_SUBJECTS
+  * Segment A Tag: ALL_SUBJECTS
+  * Segment B Tag: NO_SUBJECT
+**Case 3:** Signal created for one subject between segments that exist in that subject.
+  * Subject tag: SUBJECT_TAG_NAME
+  * Segment A Tag: SUBJECT_TAG_NAME
+  * Segment B Tag: SUBJECT_TAG_NAME
+**Case 4:** Signal created for one subject relative to another subject.
+  * Subject tag: SUBJECT_TAG_NAME
+  * Segment A Tag: SUBJECT_TAG_NAME
+  * Segment B Tag: DIFFERENT_SUBJECT_TAG_NAME