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--- visual3d:documentation:modeling:segments:segment_overview [2025/04/03 12:29] – Cleaned up the Foot section. wikisysop
+++ visual3d:documentation:modeling:segments:segment_overview [2025/04/30 19:26] (current) – Finished clean up of the page - ready for review! wikisysop
@@ Line 108: / Line 108: @@
 ===== Trunk =====
-The [[Visual3D:Documentation:Modeling:Segments:Modeling_the_Trunk|Example: Trunk]] discusses what to do if the trunk animation graphic is upside down and how one might approach modeling the thorax separate from the abdomen.
+The torso presents a challenge for modelling because of the choice in defining which end is considered proximal and which end is considered distal. It is straightforward to decide that the feet are distal to the pelvis and the hands are distal to the pelvis. The trunk is less clear. In order to have a “joint” created at the shoulders it is necessary to define the trunk to have the proximal end at the pelvis and the distal end at the shoulders.
+The [[Visual3D:Documentation:Modeling:Segments:Modeling_the_Trunk|Modelling the Trunk]] example suggests some solutions to these difficulties depending on the question being asked.
 ===== Upper Arm =====
-Defining the segment coordinate system for the humerus is particularly difficult because there are no bony landmarks to assist in determining the glenohumeral joint center, and medial and lateral markers on the epicondyles are close together and often do not represent the axis of rotation of the elbow. The explanation on [[Visual3D:Documentation:Modeling:Segments:Upper_Arm_And_Forearm|Upper_Arm_And_Forearm]] is personal opinion and users should not accept this as a recommendation, rather as one plausible approach. Further work needs to be done in this area and users must decide for themselves.
+Defining the segment coordinate system for the humerus is particularly difficult because there are no bony landmarks to assist in determining the glenohumeral joint center, and medial and lateral markers on the epicondyles are close together and often do not represent the axis of rotation of the elbow. The [[Visual3D:Documentation:Modeling:Segments:Upper_Arm_And_Forearm|Upper Arm and Forearm]] example provides a personal opinion on how to model the upper arm and related shoulder joint.
 ===== Forearm =====
-There are several challenges to defining the Forearm segment coordinate system because the Forearm is treated as a rigid segment model; supination/pronation of the forearm sometimes causes the segment coordinate system to be quite strange. On the [[Visual3D:Documentation:Modeling:Segments:Upper_Arm_And_Forearm|Upper Arm And Forearm]] page, we lay out recommendations for a static standing pose (anatomical position) and a recommendation if the static pose is the T-pose.
+There are several challenges to defining the Forearm segment coordinate system because the Forearm is treated as a rigid segment model; supination/pronation of the forearm sometimes causes the segment coordinate system to be quite strange. The [[Visual3D:Documentation:Modeling:Segments:Upper_Arm_And_Forearm|Upper Arm And Forearm]] examples lays out recommendations for a static standing pose (anatomical position) and a recommendation if the static pose is the T-pose.
-===== Other Objects =====
-==== Construct a Box ====
-  - one motion tracking marker has been attached to a box.
-  - the box will not rotate when it is raised by the subject.
-  - the box was omitted from the standing trial
 ===== Examples =====
-==== Rotate a segment coordinate system ====
+  - Rotating a segment coordinate system about its long axis (under construction)
+  - [[visual3d:tutorials:modeling:introduce_missing_digitizing_pointer_markers|Introduce missing digitizing pointer markers]]
-Rotating a segment coordinate system about its long axis.
+  - [[visual3d:documentation:modeling:segments:example_-_missing_tracking_marker_in_static_trial|Missing Tracking Marker in Static Trial]] (under construction)
-==== Example: Missing Digitizing Pointer Markers====
-[[visual3d:tutorials:modeling:introduce_missing_digitizing_pointer_markers]]
-==== Example: Missing Tracking Marker in Static Trial ====
-The following example is contrived, but it does happen.
-Consider the following right thigh segment constructed using static markers RPPT, RAPT, RPDT, RADT. These tracking markers are saved to a model template, but for the next subject the static trial is missing the RAPT marker. If the model template is applied to this trial, the right thigh segment cannot be built.
-The obvious solution to this problem is to simply remove the RAPT marker as a tracking marker, but there may be an occasion where one of the remaining 3 markers is missing for much of the movement trials because of occlusion. The solution is to replace the missing tracking target with a landmark that is placed at the expected location.