KALIBRATE
📘 Kalibrate User Manual
Version 1.73
Camera Calibration and Unreal Engine Lens Export Tool
🧭 Overview
Kalibrate is a camera calibration tool that tracks checkerboards from camera footage and exports lens parameters in a structured JSON format. A companion script then converts this JSON into a fully compatible Unreal Engine Lens File (.uasset).
🚀 Key Features:
✅ Automatic checkerboard tracking from camera footage
✅ JSON export of calibrated lens data
✅ Scripted conversion to Unreal Lens .uasset
✅ Supports both nodal and distortion parameters
✅ Compatible with Unreal Engine’s Lens Calibration System
🖥️ Interface Guide
1. Camera & Sensor Parameters
Camera Dropdown: Select the camera source to use.
⚠️ Tip: Works with webcam, USB-HDMI, or any other camera input viewable in Windows. Image will scale to match camera resolution
Resolution: Displays camera resolution (e.g., 640x360).
2. Image Acquisition
Select Folder: Choose the directory on your computer where captured calibration images will be saved.
⚠️ Tip: You can RESUME from a previous folder where you have captured images. A dialog box will autodetect the previously captured images. They must be the same checkerboard size
Reset: Clears the current calibration session. Also deletes images that don’t match the checkerboard settings
Images Taken: Counter showing how many valid frames with detected checkerboards have been captured. Pictures are taken automatically once checkerboards are detected.
3. Checkerboard Settings
Board Width: Number of inner corners across the checkerboard (e.g., 9 squares = 8 inner corners).
Board Height: Number of inner corners vertically.
Images to Capture: The system will keep capturing images until this number is reached.
⚠️ Tip: The default is 20, but feel free to increase it. It’s a balance between quality and speed that you must decide.
Square Size (mm): Real-world size of each square (in millimeters).
This is important for scaling and focal length accuracy. Default is 20 but you can increase it to match your checkerboard
⚠️ Tip: Use a rigid checkerboard and capture it from multiple angles and distances.
Checkerboard not detected: Live feedback indicating if a checkerboard pattern is visible in the frame.
Detected Checkerboard: ? x ?: Shows dimensions of the detected pattern (if found).
⚠️ Tip: There is a slight pause between photos to prevent duplicates. There is also a detection feature to ensure that you are moving the checkerboard sufficiently and that the pictures are distinct. Keep moving the checkerboard on the screen and watch the number increase.
🛠️ Tips for Best Results
Print your checkerboard on flat, non-reflective paper or rigid material.
Capture from varied angles, including edges and diagonals.
Ensure good lighting without glare.
Ensure that the sensor width and focal length are correct
Increase the number of images taken
3. Calibration
Sensor Width / Height (mm): Physical size of your camera sensor (e.g., 36mm x 24mm for full-frame). Accurate sensor size ensures correct focal length output.
⚠️ Tip: Google your camera to find the correct settings ⚠️
Calibrate: Starts the calibration process once the number of images in the folder is equal to or greater than the Images to Capture value
Focal Length: This is the measurement of the lens being used.
Results: Reprojection Error is shown.
⚠️ Tip: Lower reprojection error is better. Aim for less than <1. ⚠️
5. Export & Integration
Export JSON: Saves the calibration results into a structured JSON file.
Lens Model: Select between Spherical, Anamorphic or Polynomial
⚠️ Tip: Unreal Engine only supports Spherical or Anamorphic ⚠️
📂 Output Format
The JSON file includes:
Camera matrix
Distortion coefficients
Resolution
Sensor size
Image capture metadata
📤 Import to Unreal Engine
After generating your JSON file:
1) Open Unreal Engine and open a blank or pre-existing Unreal project.
2) Open Unreal plugins and enable Python
3) Open Unreal Plugins and Enable Camera Calibration
4) Restart Unreal Engine
5) Click File -> Execute Python Script
6) Select the Python script included in this project.
⚠️ Tip: This Python script is written for Unreal 5.4.4.
7) The script takes the JSON and generates an Unreal Lens File (.uasset).
8) This file also creates a Cine Camera in the current level with the correct Sensor Width, Sensor Height, and Focal Length
9) You can add a Lens Component as well, enable Distortion and setting Evaluation correctly