From Visual3D Wiki Documentation
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Welcome to C-Motion’s Visual3D motion analysis software. The Visual3D software provides kinematics and kinetics (inverse dynamics) calculations for biomechanical analysis of 3D motion capture data.
Prior to beginning the tutorials, if you haven't done so already, we recommend that you look over the documentation on the Visual3D Philosophy. There is some beneficial information particularly for first time users in this section.
- In the original set of tutorials, each tutorial followed from the previous tutorial. Over time additional tutorials were added that don't follow chronologically, but we have tried to group these tutorials conceptually.
- Some users find it useful to review the Visual3D workspace features before attempting the tutorials.
- Links to all data files used in the Tutorials.
- An overview of the steps for a typical processing session, including:
- - Building a model
- - Opening movement trials
- - Assigning a model to the motion trials
- - Basic signal processing
- - Model based items
- - Reporting
- Checklists are important to process oriented tasks.
- See, for example: [The Checklist Manifesto]
- There are many crucial steps in collecting "routine" motion capture data.
- The following partial list is a starting point for every Motion Capture Laboratory.
- We encourage users to contribute to this list by sending additional tasks to email@example.com
This tutorial shows the many different ways to create landmarks (virtual markers) in Visual3D.
- This tutorial describes a lower body 6 DOF model consistent with much of the research published by the Physical Disabilities Branch of the U.S. National Institutes of Health.
- This tutorial describes a lower body conventional gait model.
- This tutorial foces on the Istituto Ortopedico Rizzoli's full-body gait model.
- Plug-in Gait is one of Vicon's implementations of the Conventional Gait Model. This tutorial only covers the lower-Extremities Plug-In gait model.
- Plug-in Gait is one of Vicon's implementations of the Conventional Gait Model. This tutorial covers the full-body Plug-In gait model.
- Model based on the upper extremity model developed by Dr. George Rab, Kyria Petuskey, and Anita Bagley from Shriners Hospital for Children, Northern California. Refer to their paper "A Method for Determination of Upper Extremity Kinematics" Gait & Posture 15 (2002) 113-119 for the exact model specifics.
- This is an implementation of Vicon's Golem Model
- Modeling the thorax/ab segment
- Visual3D is a general tool capable of modeling all of the different foot models.
- This tutorial focuses on the Oxford Foot Model version implemented as a Plug-in option in Vicon's Nexus software.
- The Oxford Foot Model is a good choice for analyzing data from Children with Cerebral Palsy. If this is not your patient population, other options and other multi-segment foot models may be more appropriate.
- This tutorial focuses on the Istituto Ortopedico Rizzoli's multi-segment foot model.
- Various ways of representing the foot segment, so that the foot angle (foot relative to the laboratory) and the ankle angle (foot relative to the shank) are defined in ways that are consistent with the common colloquial uses of the angles.
- A straightforward model of the skull and mandible.
- A Virtual Laboratory is not a physical segment in Visual3D but is equivalent to a physical segment to the effect that it has a Segment Coordinate System that can be used to represent the laboratory (or other objects) and has an associated surface model that can be animated as part of the scene.
- A Virtual Laboratory is often used as the reference for segment angles (e.g. a segment relative to the laboratory) because it can accommodate the subject walking in a direction different from the laboratory coordinate system.
Using the digitizing pointer in post processing mode (e.g. from collected c3d files).
Using the digitizing pointer in Real Time streaming mode.
- Working with c3d files
- Force Platforms provide critical data for biomechanical analysis because they measure the interaction between the subject and the environment. If the subject is in contact with the floor, the joint forces, moments and powers have no physical meaning unless the reaction force data are included in the analysis.
- Instrumented treadmills are becoming common in biomechanics labs. There are three general categories of treadmills:
- Single 6 DOF sensort
- Dual 6 DOF sensors in a side/side arrangement
- Dual 6 DOF sensors in a fore/aft arrangement
- Visual3D is capable on including all of these treadmills into the inverse dynamics calculations.
- The Command Processing Pipeline provides access to the core of Visual3D’s functionality by providing a command line interface into all of Visual3D's functions. The Pipeline is typically used to automate processing steps, which is useful for multiple, repeated tasks. The Pipeline is a set of Visual3D commands that are processed in sequence. The Pipeline has the ability to manage files, define events, execute signal processing computations, create and edit models, and, create and modify reports.
- This tutorial is for advanced pipeline commands and proper pipeline development. A set of standards is also laid out for scripts and meta commands. Several commands are discussed with options that may be helpful with your script development. It is not meant to be a comprehensive discussion of each pipeline command. For a more detailed discussion go to the command wiki page. This tutorial is meant as a "sampler" to show the variety of ways the commands can be implemented.
- The Gait Profile Score (GPS) is an clinical index that can be used to describe overall gait pathology. The GPS is the mean value of a number of discreet values obtained from kinematic variables measured during gait. "[...] the RMS difference between the patient's data and the average from the reference dataset taken over all relevant kinematic variables, for the entire gait cycle.[...]" (Baker et al., 2009). This tutorial describes how to create a pipeline to compute the Gait Profile Score and Movement Analysis Profile.
- Pipeline Favorites is a very powerful way for you to list your pipeline scripts as a Table of Contents. Your list of pipeline scripts can be viewed or run from the Pipeline Favorites list box.
- This tutorial describes how to build a pipeline that will automatically focus on each kinetic events (ON and OFF) so that each force assignment can be visually inspected before generating the kinematic event (HS and TO).
- Meta-Commands are a convenient way to bundle scripts into a singles command, or to pass parameters between commands.
- Most signal processing functionality is available through the Command Pipeline, so it is advisable that you are familiar with the material in the previous Tutorial: Command Pipeline.
- Movement data is often collected for more time that is required for the analysis. This is often done to minimize the effects of filtering at the endpoints. Sometimes it is because more than one cycle can be collected at a time or to ensure that the entire cycle is collected. Sometimes it is because there are long periods of meaningless activity between epochs. Regardless of the reasons for collecting extra data, it should not be necessary to analyze all of the data. The interval of interest must be extracted from the trial. The user must be able to define a time frame of interest. Most often the region of interest is defined by specific events, such as heel strike or toe off. This can be accomplished by editing the data file or by entering the start and end frame. This process is extremely tedious and in many circumstances can be automated.
- An Event is simply an occurrence of interest that correlates to a motion capture frame, i.e. to a particular time point within a movement. The key events for gait studies (e.g., heel strike, toe-off) are now so well standardized that Visual3D can detect and mark them automatically . For other applications, you can define your own events, either manually (using the mouse to double-click on significant points on any graph) or computationally.
Identifying gait events (e.g. heel strike and toe off) with and without force platform data.
- Metrics are discrete quantitative values of signals such as maximum value, median value, value at a specified frame. In other words, metrics do not have a time-base like the other signals.
- Metrics also refer to combinations of other metric values. For example, the metric describing the range of motion of a joint angle during a movement would be the difference between the metric defining the maximum value of the joint angle and the minimum value of the joint angle. The metric describing the time for a step cycle would be the time from Right Heel Strike to Right Heel Strike.
Model Based Signals
- An overview of calculations that only make sense relative to rigid segments or local coordinate systems.
- All Kinematic and Kinetic calculations in Visual3D are described as either KINETIC_KINEMATIC Items or Link_Model_Based Items
- Kinematic calculations are based on segment coordinate systems with no reference to inertial properties.
- Kinetic (Inverse Dynamic) calculations are based on assuming linked rigid segments, "connected" by joints with 1 to 6 degree of freedom joints
- Basic EMG signal processing
- The objective of this tutorial is to provide an overview of reporting in Visual3D.
- Visual3D creates a Workspace into which all data is stored, models are integrated, and reports are produced. The entire workspace can be saved and shared as a digital report in which all the underlying analysis, data, and models can be accessed.
- Every Visual3D workspace includes exactly one report, which is initially blank, and to which you may add any number of distinct pages. In a sense, the entire workspace is itself a kind of extended electronic report, which contains not only the contents of the Reporting page but also all of the original data and records of all data-processing steps.
- The objective of this tutorial is to demonstrate how two data sets can be compared in the Reports. The basis of the comparison is by grouping trials.
- The objective of this tutorial is to demonstrate how normal data can be added to a report.
- More report tutorials can be found here, such as adding an image to a report.
Real Time Streaming
- More tutorials can be found on C-Motion's YouTube account:
- Some of these YouTube tutorials have associated wiki tutorials.
- Description of format for sending data to support