robotai.github.io

Calibration Procedures

Calibration Overview

Calibration ensures accurate color, white balance, and depth measurements. Regular calibration is recommended for consistent results.

Calibration Frequency:

Pre-Calibration Checklist

White Balance Calibration

Method 1: Using White Reference Card

Required Materials:

Procedure:

  1. Position Reference Card
    • Place white card in front of camera
    • Ensure full coverage of frame
    • Position at normal working distance
    • Avoid shadows on card
    • Ensure even lighting
  2. Capture Reference Image
    • Open RobotAI Camera software
    • Navigate to Calibration > White Balance
    • Click Capture White Reference
    • Camera captures image of white card
    • Do not move card during capture
  3. Apply Calibration
    • Software analyzes white reference
    • Click Apply Calibration
    • “Success” message confirms
    • New white balance saved
  4. Verify Results
    • Remove white card
    • Check live view colors
    • Colors should appear neutral
    • Test on neutral gray object

Method 2: Manual Color Temperature

For Known Lighting Conditions:

  1. Determine color temperature of lighting
  2. Open Settings > White Balance > Manual
  3. Enter color temperature in Kelvin
  4. Apply to current settings

Common Color Temperatures:

Color Accuracy Calibration

Using ColorChecker Passport

Required Materials:

Procedure:

  1. Capture ColorChecker Image
    • Position ColorChecker in scene
    • Ensure even lighting
    • No shadows on card
    • Fill ~50% of frame
    • Capture image
  2. Analyze Color Data
    • Open Calibration > Color Accuracy
    • Load ColorChecker image
    • Software identifies color patches
    • Calculates color accuracy
    • Generates correction profile
  3. Apply Color Profile
    • Review color analysis results
    • Delta E values < 2 are excellent
    • Click Generate Profile
    • Profile applied to camera
    • Save profile with date

Verification

  1. Capture new ColorChecker image
  2. Compare with calibration target
  3. Colors should match within Delta E < 1

Depth Calibration

Depth Accuracy Calibration

Required Materials:

Procedure:

  1. Prepare Calibration Setup
    • Place calibration plate on flat surface
    • Ensure plate is level
    • Position camera perpendicular to plate
    • Measure distance: 300mm to 1500mm
    • Mark measurement distance
  2. Capture Calibration Data
    • Open Calibration > Depth
    • Enter actual distance to plate
    • Click Capture Calibration
    • Camera captures depth map
    • Process multiple distances
  3. Multi-Point Calibration
    • Capture at 5-7 different distances
    • Recommended: 300mm, 500mm, 700mm, 900mm, 1100mm, 1300mm, 1500mm
    • Each point improves accuracy
    • Allow 10 seconds between captures
  4. Analyze Results
    • Software calculates calibration curve
    • Displays accuracy at each distance
    • Average accuracy should be < ±1mm
    • Graphs show any systematic errors
  5. Apply Calibration
    • Click Apply Depth Calibration
    • New calibration saved
    • Restart software to apply fully

Depth Quality Verification

After Calibration:

  1. Capture test objects at various distances
  2. Compare camera measurements to actual
  3. Accuracy should meet specifications
  4. Document results for reference

Geometric Calibration

Lens Distortion Calibration

Required Materials:

Procedure:

  1. Capture Distortion Reference
    • Display checkerboard pattern
    • Fill entire camera frame
    • Capture multiple angles
    • Tilt pattern ±30 degrees
    • Capture 5-10 images
  2. Analyze Distortion
    • Open Calibration > Geometric
    • Load checkerboard images
    • Software detects grid points
    • Calculates distortion coefficients
    • Identifies barrel or pincushion distortion
  3. Apply Correction
    • Review distortion analysis
    • Click Calculate Distortion Map
    • Apply correction to all captures
    • Save calibration data

Thermal Calibration

Temperature Compensation

Camera automatically compensates for temperature changes, but manual calibration improves accuracy.

Procedure:

  1. Cold Calibration (below 10°C)
    • Allow camera to stabilize at cold temperature
    • Open Calibration > Thermal
    • Click Capture Cold Reference
    • Camera records baseline
  2. Warm Calibration (above 35°C)
    • Allow camera to warm up
    • Click Capture Warm Reference
    • Records warm baseline
  3. Apply Thermal Compensation
    • Software creates compensation curve
    • Automatically adjusts for temperature
    • Improves accuracy across temperature range

Periodic Calibration Validation

Weekly Validation

  1. Capture white balance reference
  2. Compare to stored profile
  3. If Delta E > 2, perform full white balance calibration
  4. Document results

Monthly Comprehensive Check

  1. Perform white balance calibration
  2. Perform color accuracy calibration
  3. Verify depth accuracy at 3 distances
  4. Check geometric distortion
  5. Document all results
  6. Generate calibration report

Calibration Management

Save Calibration Profile

  1. After successful calibration
  2. Click Save Calibration As…
  3. Enter profile name with date
  4. Example: Calibration_2024_07_22_Office_Lighting
  5. Add notes about conditions

Load Calibration Profile

  1. Open Calibration > Load Profile
  2. Select calibration from list
  3. Software loads all settings
  4. Apply when conditions match

Calibration History

View Calibration Log:

Troubleshooting Calibration

Common Issues

“Calibration Failed” Message:

Poor Color Accuracy After Calibration:

Depth Accuracy Errors:

Inconsistent Results:

Best Practices

  1. Calibrate on Installation - Perform full calibration before first use
  2. Consistent Lighting - Calibrate in typical working conditions
  3. Document Environment - Note temperature, lighting, location
  4. Regular Validation - Check accuracy weekly
  5. Multiple Profiles - Create profiles for different lighting conditions
  6. Archive Results - Keep historical calibration data
  7. Clean Lens - Clean optics before calibration
  8. Stable Setup - Use rigid mounting during calibration

See Also