Cinematographer
Die Marker am Performer sind für das Infrarot-System, nicht für meine Kamera. Bei kombinierten Shoots muss ich sie oft später digital entfernen lassen.
Small retroreflective spheres attached to performers and objects during optical motion capture sessions – reflecting infrared light back to tracking cameras to enable precise 3D position tracking of body movement, facial expressions, and prop locations for animation data capture.
What are Motion Capture Markers?
Motion Capture Markers are small retroreflective spheres that are attached to performers in optical motion capture. They reflect infrared light back to the cameras, which track their 3D position in space.
Basic Principle
| Aspect | Description |
|---|---|
| Material | Retroreflective |
| Shape | Mostly spherical |
| Function | Reflect IR light |
| Tracking | Capture 3D position |
Marker Types
| Type | Description |
|---|---|
| Passive | Reflective |
| Active | LED-lit |
| Spherical | Spherical |
| Hemispherical | Hemispherical |
Passive Markers
| Property | Description |
|---|---|
| Material | 3M Retroreflective |
| Function | Reflects IR |
| Advantage | No power supply |
| Standard | Industry common |
Active Markers
| Property | Description |
|---|---|
| Function | Emits light |
| Advantage | Unique ID |
| Disadvantage | Power supply needed |
| Application | Specialized |
Sizes
| Diameter | Application |
|---|---|
| 4mm | Fingers, Face |
| 9mm | Facial Capture |
| 14mm | Body Standard |
| 19mm+ | Large Volumes |
Marker Placement
| Body Area | Typical Count |
|---|---|
| Full Body | 40-60 |
| Upper Body | 20-30 |
| Face | 50-150 |
| Hands | 20-30 per hand |
Body Marker Layout
| Area | Markers |
|---|---|
| Head | 4-5 |
| Torso | 8-12 |
| Arms | 8-10 per arm |
| Legs | 8-10 per leg |
Facial Markers
| Aspect | Description |
|---|---|
| Size | Small (4-9mm) |
| Density | High |
| Placement | Muscle groups |
| Tracking | FACS-based |
Attachment
| Method | Description |
|---|---|
| Velcro | On suit |
| Tape | Double-sided |
| Adhesive | For skin (face) |
| Snaps | Quick-Release |
Marker Sets
| Set | Description |
|---|---|
| Standard Body | Predefined |
| Custom | Project-specific |
| Prop Set | For objects |
| Facial Set | Face-specific |
Asymmetrical Layout
| Aspect | Description |
|---|---|
| Reason | Marker identification |
| Method | Slightly offset |
| Advantage | Less swapping |
| Standard | Best practice |
Calibration
| Step | Description |
|---|---|
| Wall | Volume calibration |
| T-Pose | Performer reference |
| Range of Motion | Movement range |
| Label | Name markers |
Marker Swap
| Problem | Description |
|---|---|
| Cause | Confusion |
| When | Crossing markers |
| Solution | Manual fix |
| Prevention | Asymmetry |
Occlusion
| Aspect | Description |
|---|---|
| Problem | Marker obscured |
| Cause | Body, props |
| Solution | More cameras |
| Interpolation | Fill gaps |
Maintenance
| Aspect | Description |
|---|---|
| Cleaning | Regularly |
| Storage | Protected |
| Replacement | If damaged |
| Quality | Check |
Quality Issues
| Problem | Cause |
|---|---|
| Dim Reflection | Dirt, wear |
| Deformation | Damaged |
| Ghosting | Defective |
| Flicker | Loose |
Manufacturers
| Brand | System |
|---|---|
| Vicon | Vicon Markers |
| OptiTrack | Passive/Active |
| Qualisys | QTM Markers |
| PhaseSpace | Active LED |
Vicon Markers
| Type | Description |
|---|---|
| Standard | 14mm Spheres |
| Small | 9mm for detail |
| Large | 19mm+ for distance |
| Custom | Special orders |
OptiTrack Markers
| Type | Description |
|---|---|
| Standard | Versatile |
| Mini | For hands/face |
| Active | LED-based |
| Rigid Body | For props |
Cost
| Factor | Description |
|---|---|
| Per Marker | Inexpensive individually |
| Sets | Package prices |
| Consumption | Wear and tear |
| Quality | Pays off |
DIY vs. Professional
| Aspect | DIY | Professional |
|---|---|---|
| Quality | Variable | Consistent |
| Price | Cheaper | Higher |
| Tracking | Okay | Optimal |
| Recommendation | Tests | Production |
Best Practices
| Practice | Reason |
|---|---|
| Quality Markers | Better data |
| Asymmetrical | Less swapping |
| Secure Attachment | No slippage |
| Spare Markers Ready | Quick replacement |
Today
Motion Capture Markers are a fundamental component of optical mocap systems. Despite advancements in markerless tracking, marker-based systems remain the standard for precise motion capture in film and gaming. The quality of the markers and their correct placement directly influence the quality of the captured data.
From the crafts
Perspectives
Director
Die Marker-Positionen bestimmen, welche Bewegungen wir erfassen können. Ein gutes Marker-Setup ist Voraussetzung für akkurate Daten.
Producer
Marker-Qualität und korrektes Placement sparen Zeit in der Datenverarbeitung. Fehlende oder verrutschte Marker verursachen teure Manual-Fixes in der Post.
More in the lexikon
Related terms
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Mocap Suit / Motion Capture Suit / Performance Capture Suit / Tracking Suit
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Vicon
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OptiTrack / NaturalPoint OptiTrack / OptiTrack Motion Capture
Camera · Technique
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Recording an actor's facial expressions, typically via head-mounted camera (HMC), to…
Test your knowledge
Quiz
1. Was beschreibt „Motion-Capture-Marker / Mocap-Marker / Tracking-Marker / Reflektierende Marker" am besten?
2. Zu welchem Department gehört „Motion-Capture-Marker / Mocap-Marker / Tracking-Marker / Reflektierende Marker"?
3. Wie viele verschiedene Fachperspektiven bietet dieser Eintrag?