Pattern pose estimation

The pose estimation is done in a similar manner to marker pose estimation from the previous chapter. As usual we need 2D-3D correspondences to estimate the camera-extrinsic parameters. We assign four 3D points to coordinate with the corners of the unit rectangle that lies in the XY plane (the Z axis is up), and 2D points correspond to the corners of the image bitmap.

PatternDetector.cpp

The buildPatternFromImage class creates a Pattern object from the input image as follows:

void PatternDetector::buildPatternFromImage(const cv::Mat& image, Pattern& pattern) const
{
    int numImages = 4;
    float step = sqrtf(2.0f);

    // Store original image in pattern structure
    pattern.size = cv::Size(image.cols, image.rows);
    pattern.frame = image.clone();
    getGray(image, pattern.grayImg);
    
    // Build 2d and 3d contours (3d contour lie in XY plane since // it's planar)
    pattern.points2d.resize(4);
    pattern.points3d.resize(4);

    // Image dimensions...