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--- metric_convex_hull_across_frames [2025/10/06 18:12] – created wikisysop
+++ metric_convex_hull_across_frames [2025/10/06 19:52] (current) – [Example: 3D convex hull] wikisysop
@@ Line 51: / Line 51: @@
 ====Example: 2D convex hull====
+Here the **Metric Compute Volume of a Convex Hull Across Frames** command is used to compute the convex hull for right and left foot GRF data during a balance trial. By computing a 2 dimensional (X and Y) hull for the GRF at each foot we can make comparisons between sides while balancing and identify potential asymmetry.
+The command is as so:
+<code>
+Metric_Compute_Volume_of_a_Convex_Hull_Across_Frames
+/SIGNAL_TYPES=FORCE
+/SIGNAL_FOLDER=ORIGINAL
+/SIGNAL_NAMES=FP3
+/RESULT_FOLDER=PROCESSED
+/RESULT_NAME=GRF_right_hull
+/NUMBER_OF_DIMENSIONS=2
+/COMPONENT_SEQUENCE=X+Y
+/REQUIRE_ALL_SIGNALS=TRUE
+! /START_FRAME=
+! /END_FRAME=
+/EVENT_SEQUENCE=Start+End
+! /EXCLUDE_EVENTS=
+;
+Metric_Compute_Volume_of_a_Convex_Hull_Across_Frames
+/SIGNAL_TYPES=FORCE
+/SIGNAL_FOLDER=ORIGINAL
+/SIGNAL_NAMES=FP4
+/RESULT_FOLDER=PROCESSED
+/RESULT_NAME=GRF_left_hull
+/NUMBER_OF_DIMENSIONS=2
+/COMPONENT_SEQUENCE=X+Y
+/REQUIRE_ALL_SIGNALS=TRUE
+! /START_FRAME=
+! /END_FRAME=
+/EVENT_SEQUENCE=Start+End
+! /EXCLUDE_EVENTS=
+;
+</code>
+The resulting metrics show the area of the 2 dimensional hull created for each side, a larger area points to more variation in force during the trial.
+Results:
+{{:hull_left.png|}}{{:hull_right.png|}}
 ====Example: 3D convex hull====
+In this example **Metric Compute Volume of a Convex Hull Across Frames** is used to find the volume occupied by an individual's thorax segment between events as defined in the workspace.
+The pipeline command is as follows:
+<code>
+Metric_Compute_Volume_of_a_Convex_Hull_Across_Frames
+/SIGNAL_TYPES=TARGET
+! /SIGNAL_FOLDER=ORIGINAL
+/SIGNAL_NAMES=CLAV+STRN+CV7+T10+RSHO+LSHO
+! /RESULT_FOLDER=PROCESSED
+/RESULT_NAME=Upper_Thorax_Volume
+/NUMBER_OF_DIMENSIONS=3
+/COMPONENT_SEQUENCE=ALL
+! /REQUIRE_ALL_SIGNALS=TRUE
+! /START_FRAME=
+! /END_FRAME=
+/EVENT_SEQUENCE=EVENT1+EVENT2
+! /EXCLUDE_EVENTS=
+;
+</code>
+Here a 3 dimensional hull is used as the resulting metric will represent a 3 dimensional structure in space. The resulting metric value represents the approximate volume of the space that the upper thorax segment travels through between the events listed:
+{{:thorax_volume.png|}}
 ====Additional Resources:====
-[[https://www.cis.upenn.edu/~jean/gbooks/new281-282.pdf|Delaunay Triangulation]]
+[[https://www.cis.upenn.edu/~jean/gbooks/new281-282.pdf|Delaunay Triangulation]]\\
 [[https://www.geeksforgeeks.org/dsa/convex-hull-algorithm/|Convex Hull Algorithm]]