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Get camera parameters

Before see this docs, check below docs

Detailed Description part of OpenCV's official docs

Previous docs
Simply call stitch
Estimation and compose

What is difference?

In previous example,

  • calculate camera parameters with estimateTransform
  • compose images to panorama image with camera parameter
Stitcher::Status status = stitcher->estimateTransform(imgs);
///checking error
stitcher->composePanorama(output);

In this example, Let's check how they store camera parameters in structure

Stitcher::Status status = stitcher->estimateTransform(imgs);

///checking error

vector<detail::CameraParams> cameras = stitcher->cameras();

for(int i = 0; i < imgs.size(); i++)
{
    DEBUG_PRINT_OUT("----Image index " << i << " camera parameters----");
    DEBUG_PRINT_OUT("Camera intrinsic matrix");
    DEBUG_PRINT_OUT(cameras[i].K());

    DEBUG_PRINT_OUT("Focal length : " << cameras[i].focal);

    DEBUG_PRINT_OUT("Aspect ratio : " << cameras[i].aspect);

    DEBUG_PRINT_OUT("Principle Point X : " << cameras[i].ppx);

    DEBUG_PRINT_OUT("Principle Point Y : " << cameras[i].ppy);

    DEBUG_PRINT_OUT("Rotation matrix");
    DEBUG_PRINT_OUT(cameras[i].R);

    DEBUG_PRINT_OUT("Translation matrix");
    DEBUG_PRINT_OUT(cameras[i].t);
    DEBUG_PRINT_OUT(" ");
}

structure

What is CameraParams?

Call cameras getter from Stitcher API, You can get camera parameters

vector<detail::CameraParams> cameras = stitcher->cameras();

Definition of this structure is in OpenCV's stitcher moduls's detail
"include/opencv2/stitching/detail/camera.hpp"

struct CV_EXPORTS CameraParams
{
    CameraParams();
    CameraParams(const CameraParams& other);
    const CameraParams& operator =(const CameraParams& other);
    Mat K() const;

    double focal; // Focal length
    double aspect; // Aspect ratio
    double ppx; // Principal point X
    double ppy; // Principal point Y
    Mat R; // Rotation
    Mat t; // Translation
};
  • K matrix
    camera's intrinsic matrix, include Focal length and Principle point
  • focal
    Focal length
  • aspect
    Scale factor
  • ppx and ppy
    Principle point
  • R matrix
    Rotation matrix
  • t matrix
    Translation matrix

With these informations, You can do another work that camera parmameter related.

Result print out

With this repo's sample images

----Image index 0 camera parameters----
Camera intrinsic matrix
[709.650348798485, 0, 447;
 0, 709.650348798485, 335.5;
 0, 0, 1]
Focal length : 709.65
Aspect ratio : 1
Principle Point X : 447
Principle Point Y : 335.5
Rotation matrix
[0.93108684, 0.035384167, -0.36307758;
 0.0001988858, 0.99523526, 0.097501867;
 0.36479765, -0.090854913, 0.92664331]
Translation matrix
[0;
 0;
 0]
 
----Image index 1 camera parameters----
Camera intrinsic matrix
[719.9602633448541, 0, 447;
 0, 719.9602633448541, 335.5;
 0, 0, 1]
Focal length : 719.96
Aspect ratio : 1
Principle Point X : 447
Principle Point Y : 335.5
Rotation matrix
[0.99949676, 0.0036283, -0.031512056;
 -0.00032901776, 0.99456888, 0.10407893;
 0.031718541, -0.10401618, 0.99406964]
Translation matrix
[0;
 0;
 0]
 
----Image index 2 camera parameters----
Camera intrinsic matrix
[743.4787164662755, 0, 447;
 0, 743.4787164662755, 335.5;
 0, 0, 1]
Focal length : 743.479
Aspect ratio : 1
Principle Point X : 447
Principle Point Y : 335.5
Rotation matrix
[0.91788989, -0.042156182, 0.39458963;
 0.00015651435, 0.99437976, 0.10587097;
 -0.39683512, -0.09711612, 0.91273779]
Translation matrix
[0;
 0;
 0]