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--- visual3d:documentation:pipeline:metric_commands:metric_frames_between_events [2025/09/18 18:00] – wikisysop
+++ visual3d:documentation:pipeline:metric_commands:metric_frames_between_events [2025/09/24 13:43] (current) – [Complex Example: Finding time between events using frame rate] wikisysop
@@ Line 41: / Line 41: @@
 The dialog box allows you to assign values to the command parameters outlined above.
-===== Example =====
+====Simple Example: Frames between steps====
+If you are conducting analysis on a gait trial with gait events that have been defined, you can use **Metric Frames Between Events** to find the number of frames between each stride and compare. The number of frames separating one stride from another can be an indication of stride length and/or walking speed. Use the pipeline command below to perform the operation.
-\\
+<code>
+Metric_Frames_Between_Events
+! /RESULT_METRIC_FOLDER=PROCESSED
+/RESULT_METRIC_NAME=Frames_Between_Strides
+/EVENT_SEQUENCE=LTO+RHS
+/EXCLUDE_EVENTS=
+/GENERATE_MEAN_AND_STDDEV=TRUE
+! /APPEND_TO_EXISTING_VALUES=FALSE
+;
+</code>
+A new metric folder containing the following data can be seen:
-|<code>\\ Metric_Frames_Between_Events\\ /RESULT_METRIC_NAME=Right_Terminal_Double_Limb_Support\\ ! /RESULT_METRIC_FOLDER=PROCESSED\\ /EVENT_SEQUENCE=LHS+RTO\\ /EXCLUDE_EVENTS=LTO+RHS\\ ! /GENERATE_MEAN_AND_STDDEV=TRUE\\ ! /APPEND_TO_EXISTING_VALUES=FALSE\\ ;\\ </code>  |  {{:MetricTimeBtwnEventsDlg_Example.jpg}}|
+{{:visual3d:documentation:pipeline:metric_commands:frames_between.png?400|}}
+====Complex Example: Finding time between events using frame rate====
+Most movement trials will provide important trial information, like capture rate, along with the data. Using this data we can calculate important values, like stride time, if they aren't already available. Here we will use **Automatic Gait Events**, **Metric Frames Between Events**, and **Divide Signals by Constant** to calculate the average time between heel strikes in a gait trial.
+First, we will use the automatic gait events command to add tags to events in the trial like heel strikes and toe offs.
+<code>
+Automatic_Gait_Events
+! /FRAME_WINDOW=8
+! /USE_TPR=TRUE
+! /TPR_EVENT_INSTANCE=1
+;
+</code>
+Now that these events have been defined we can use **Metric Frames Between Events** to determine how many frames pass between each left toe off and the next heel strike, as well as the mean.
+<code>
+Metric_Frames_Between_Events
+! /RESULT_METRIC_FOLDER=PROCESSED
+/RESULT_METRIC_NAME=Frames_Between_Strides
+/EVENT_SEQUENCE=LTO+LHS
+/EXCLUDE_EVENTS=
+! /GENERATE_MEAN_AND_STDDEV=TRUE
+! /APPEND_TO_EXISTING_VALUES=FALSE
+;
+</code>
+Using the capture rate of 150 frames/second for this trial (often found in the parameters folder) we can now calculate the time between each frame using **Divide Signal By Constant**. By dividing the time between each event by the capture rate (constant) we can calculate the time. This will be done for each stride as well as for the mean stride time.
+<code>
+Divide_Signal_By_Constant
+/SIGNAL_TYPES=METRIC
+/SIGNAL_FOLDER=PROCESSED
+/SIGNAL_NAMES=Frames_Between_Strides_MEAN
+/SIGNAL_COMPONENTS=ALL
+! /RESULT_TYPES=
+/RESULT_FOLDERS=Stride_Calculation
+/RESULT_NAME=Stride_Time_MEAN
+/APPLY_AS_SUFFIX_TO_SIGNAL_NAME=FALSE
+/CONSTANT=150
+;
+</code>
+<code>
+Divide_Signal_By_Constant
+/SIGNAL_TYPES=METRIC
+/SIGNAL_FOLDER=PROCESSED
+/SIGNAL_NAMES=Frames_Between_Strides
+/SIGNAL_COMPONENTS=ALL
+! /RESULT_TYPES=
+/RESULT_FOLDERS=Stride_Calculation
+/RESULT_NAME=Stride_Time
+/APPLY_AS_SUFFIX_TO_SIGNAL_NAME=FALSE
+/CONSTANT=150
+;
+</code>
+You should now see two new folders named **Stride_Time** and **Stride_Time_MEAN** containing stride time data for each trial.
+{{:visual3d:documentation:pipeline:metric_commands:stride_time.png?500|}}
+{{:visual3d:documentation:pipeline:metric_commands:stride_time_mean.png?500|}}
 ==== Visual3D Versions supporting Subject Prefixes ====