====== Compute GPS and GDI ======

In this tutorial, we will walk through how to compute the [[sift:gait_measures:gait_profile_score|Gait Profile Score]] (GPS) and  [[sift:gait_measures:gait_deviation_index|Gait Deviation Index]] (GDI) using a Normal Database (ND) we derived in the previous [[Sift:Tutorials:build_normal_database|tutorial]].\\
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=====Starting Point=====

If you do not have a [[sift:build_nds:building_normal_databases|Sift ND]] file generated, please follow the previous tutorial BEFORE completing this one: [[Sift:Tutorials:build_normal_database|Build ND Tutorial]]\\

If you wish to follow this tutorial with a premade Sift ND file, download here: \\

==== 1. Load Library ====

On the [[Sift:application:Load_page|Load Page]], select **Load Library** and navigate to the library of CMZ workspaces you wish to compute the GPS and/or GDI measure on. \\

===== 2. Run External Script =====

In this specific tutorial, we have loaded a library that does not have all of the 15 kinematic features necessary for the [[sift:gait_measures:gait_profile_score|GPS]] and [[sift:gait_measures:gait_profile_score|GDI]]. Therefore, we need to make sure we have the correct joint angles computed in our CMZ workspaces. To do so, we are going to run a Visual3D pipeline script (.v3s file) against the loaded library. \\

==== Pipeline Script ====
The pipeline can be found here: \\
**Note**: this pipeline was derived for the sample workspace associated with this tutorial. If running this against your own data, make sure to verify the Link_Model_Based calculations with the GPS definitions to insure you have the correct angles. \\
A sample of this pipeline script can be seen here:\\
  !/////////////////////////////////////////////////////////////////////////////////////////////////
  !		Compute LEFT Joint Angles
  !/////////////////////////////////////////////////////////////////////////////////////////////////

  ! Left Angles are calculated in accordance to the GPS score

  ! Left Ankle
  Compute_Model_Based_Data
  /RESULT_NAME=L_Ankle_Angle
  /SUBJECT_TAG=ALL_SUBJECTS
  /FUNCTION=JOINT_ANGLE
  /SEGMENT=LMF
  /REFERENCE_SEGMENT=LSK
  /RESOLUTION_COORDINATE_SYSTEM=
  ! /USE_CARDAN_SEQUENCE=FALSE
  ! /NORMALIZATION=FALSE
  ! /NORMALIZATION_METHOD=
  ! /NORMALIZATION_METRIC=
  ! /NEGATEX=FALSE
  ! /NEGATEY=FALSE
  ! /NEGATEZ=FALSE
  ! /AXIS1=X
  ! /AXIS2=Y
  ! /AXIS3=Z
  ! /TREADMILL_DATA=FALSE
  ! /TREADMILL_DIRECTION=UNIT_VECTOR(0,1,0)
  ! /TREADMILL_SPEED=0.0
  ;

  ! Left Knee
  Compute_Model_Based_Data
  /RESULT_NAME=L_Knee_Angle
  /SUBJECT_TAG=ALL_SUBJECTS
  /FUNCTION=JOINT_ANGLE
  /SEGMENT=LSK
  /REFERENCE_SEGMENT=LTH
  /RESOLUTION_COORDINATE_SYSTEM=
  ! /USE_CARDAN_SEQUENCE=FALSE
  ! /NORMALIZATION=FALSE
  ! /NORMALIZATION_METHOD=
  ! /NORMALIZATION_METRIC=
  ! /NEGATEX=FALSE
  ! /NEGATEY=FALSE
  ! /NEGATEZ=FALSE
  ! /AXIS1=X
  ! /AXIS2=Y
  ! /AXIS3=Z
  ! /TREADMILL_DATA=FALSE
  ! /TREADMILL_DIRECTION=UNIT_VECTOR(0,1,0)
  ! /TREADMILL_SPEED=0.0
  ;
\\
{{ sift:tutorials:gpsgditut_loadnd.png?600}}
==== Run V3D Engine Dialog ====

  - To run this script, the [[Sift:application:run_v3d_engine_dialog|Run V3D Engine Dialog]]] can be accessed through the {{:sift_run_v3d.png?30}} button on the [[Sift:Application:Toolbar|toolbar]].\\
  - Add the .v3s script downloaded from this tutorial and select **"Run Scripts"**.\\
  - Wait for the CMZs to update and the library to load.\\

==== 3. Load Sift ND ====

On the [[Sift:application:Load_page|Load Page]], select **Load ND** and navigate to the Sift ND CMZ file generated in the previous tutorial, or your own Sift ND file. \\

The Load Page should now display both the library data and ND data, like the image to the right of the page.\\

The ND we have loaded contains the 15 kinematic joint angles for the [[sift:gait_measures:gait_profile_score|GPS]] and [[sift:gait_measures:gait_profile_score|GDI]] definitions. \\

The ND also has a Mean summary statistic signal for both Workspace and Library level. Both workspace means and the library mean are **REQUIRED** for the GDI measure. The Library level mean signal is **REQUIRED** for the GPS.\\

**IF** your Sift ND does not follow these requirements, please follow the previous tutorial [[Sift:Tutorials:build_normal_database|here]] to build a ND with the correct summary data.\\