flutter_camera_calibration

"flutter_camera_calibration plugin project"

1. Introduction

• The flutter_camera_calibration plugin project provides camera calibration functionality for iOS and Android using the OpenCV 4.3.0 library.

  It allows you to obtain the camera's intrinsic parameters.

• This functionality is achieved by adapting the C++ camera calibration code provided in the OpenCV tutorials for use in Flutter.

  The project uses the FFI (Foreign Function Interface) library to bind these C++ functions for use in Flutter.

• In the example code, you will notice the usage of both file_picker and image_picker.

  Additionally, you can download the configuration file and test images from the following link:

  https://github.com/deokgyuhan/flutter_camera_calibration/tree/master/ScreenShots/data

• Furthermore, please be aware that testing is not supported in the simulator when running the examples, and you should test them on an actual device.

2. Screenshots

Home	Config File Select	Captured Images Select	Camera Intrinsic Parameter Matrix

3. Setup

• The permission settings required for file_picker and image_picker can be found in the respective plugin installation documentation for iOS and Android.

4. Usage

import 'package:flutter_camera_calibration/flutter_camera_calibration.dart' as flutter_camera_calibration;

//get opencv version
var version = flutter_camera_calibration.opencvVersion();

//get camera intrinsic parameter begin
String? filePath = ""; 
String full_path = "";   //config file path

//select config file 'in_VID5.xml'
FilePickerResult? result = await FilePicker.platform.pickFiles();
if (result != null) {
filePath =  result.files.single.path;
full_path = filePath.toString();
if(filePath != null) {
 // print("------------->"+filePath); 
}
} else {
// User canceled the picker
}

//select Captured images
final List<XFile>? images = await _picker.pickMultiImage();
final List<String> imagePaths = [];

if(images != null) {
for (final image in images) {
final imagePath = image?.path ?? "none";
// print("-----------"+imagePath.toString());
imagePaths.add(imagePath);
}
}

//get camera intrinsic parameter begin
final calibration_result = await flutter_camera_calibration.cameraCalibrate(full_path, imagePaths);

var matrix = flutter_camera_calibration.CameraIntrincMatrix(
  calibration_result.rows,
  calibration_result.cols,
  calibration_result.array,
);

print(matrix);
//get camera intrinsic parameter end

- Reference -

• the official OpenCV documentation.

Camera Calibration Theory

• OpenCV Camera Calibration Example: https://docs.opencv.org/4.3.0/d4/d94/tutorial_camera_calibration.html

• file picker: https://pub.dev/packages/file_picker

• image picker: https://pub.dev/packages/image_picker