monado/src/xrt/auxiliary/tracking/t_calibration_opencv.h

// Copyright 2019, Collabora, Ltd.
// SPDX-License-Identifier: BSL-1.0
/*!
 * @file
 * @brief  OpenCV calibration helpers.
 * @author Pete Black <pblack@collabora.com>
 */

#pragma once

#include <opencv2/opencv.hpp>
#include <sys/stat.h>

#ifdef __cplusplus
extern "C" {
#endif


struct opencv_calibration_params
{
	cv::Mat l_intrinsics;
	cv::Mat l_distortion;
	cv::Mat l_distortion_fisheye;
	cv::Mat l_translation;
	cv::Mat l_rotation;
	cv::Mat l_projection;
	cv::Mat r_intrinsics;
	cv::Mat r_distortion;
	cv::Mat r_distortion_fisheye;
	cv::Mat r_translation;
	cv::Mat r_rotation;
	cv::Mat r_projection;
	cv::Mat disparity_to_depth;
	cv::Mat mat_image_size;
};

static bool
write_cv_mat(FILE* f, cv::Mat* m)
{
	uint32_t header[3];
	header[0] = static_cast<uint32_t>(m->elemSize());
	header[1] = static_cast<uint32_t>(m->rows);
	header[2] = static_cast<uint32_t>(m->cols);
	fwrite(static_cast<void*>(header), sizeof(uint32_t), 3, f);
	fwrite(static_cast<void*>(m->data), header[0], header[1] * header[2],
	       f);
	return true;
}

static bool
read_cv_mat(FILE* f, cv::Mat* m)
{
	uint32_t header[3];
	fread(static_cast<void*>(header), sizeof(uint32_t), 3, f);
	//! @todo We may have written things other than CV_32F and CV_64F.
	if (header[0] == 4) {
		m->create(static_cast<int>(header[1]),
		          static_cast<int>(header[2]), CV_32F);
	} else {
		m->create(static_cast<int>(header[1]),
		          static_cast<int>(header[2]), CV_64F);
	}
	fread(static_cast<void*>(m->data), header[0], header[1] * header[2], f);
	return true;
}

XRT_MAYBE_UNUSED static bool
calibration_get_stereo(char* configuration_filename,
                       uint32_t frame_w,
                       uint32_t frame_h,
                       bool use_fisheye,
                       cv::Mat* l_undistort_map_x,
                       cv::Mat* l_undistort_map_y,
                       cv::Mat* l_rectify_map_x,
                       cv::Mat* l_rectify_map_y,
                       cv::Mat* r_undistort_map_x,
                       cv::Mat* r_undistort_map_y,
                       cv::Mat* r_rectify_map_x,
                       cv::Mat* r_rectify_map_y,
                       cv::Mat* disparity_to_depth)
{
	struct opencv_calibration_params cp;
	cv::Mat zero_distortion = cv::Mat(5, 1, CV_32F, cv::Scalar(0.0f));

	char path_string[256]; //! @todo 256 maybe not enough
	//! @todo Use multiple env vars?
	char* config_path = secure_getenv("HOME");
	snprintf(path_string, 256, "%s/.config/monado/%s.calibration",
	         config_path, configuration_filename); //! @todo Hardcoded 256

	FILE* calib_file = fopen(path_string, "rb");
	if (calib_file == NULL) {
		return false;
	}

	// Read our calibration from this file
	read_cv_mat(calib_file, &cp.l_intrinsics);
	read_cv_mat(calib_file, &cp.r_intrinsics);
	read_cv_mat(calib_file, &cp.l_distortion);
	read_cv_mat(calib_file, &cp.r_distortion);
	read_cv_mat(calib_file, &cp.l_distortion_fisheye);
	read_cv_mat(calib_file, &cp.r_distortion_fisheye);
	read_cv_mat(calib_file, &cp.l_rotation);
	read_cv_mat(calib_file, &cp.r_rotation);
	read_cv_mat(calib_file, &cp.l_translation);
	read_cv_mat(calib_file, &cp.r_translation);
	read_cv_mat(calib_file, &cp.l_projection);
	read_cv_mat(calib_file, &cp.r_projection);
	read_cv_mat(calib_file, disparity_to_depth); // provided by caller
	read_cv_mat(calib_file, &cp.mat_image_size);

	//! @todo Scale Our intrinsics if the frame size we request
	//              calibration for does not match what was saved

	cv::Size image_size(int(cp.mat_image_size.at<float>(0, 0)),
	                    int(cp.mat_image_size.at<float>(0, 1)));

	// Generate undistortion maps - handle fisheye or rectilinear sources

	if (use_fisheye) {
		cv::fisheye::initUndistortRectifyMap(
		    cp.l_intrinsics, cp.l_distortion_fisheye, cv::noArray(),
		    cp.l_intrinsics, image_size, CV_32FC1, *l_undistort_map_x,
		    *l_undistort_map_y);
		cv::fisheye::initUndistortRectifyMap(
		    cp.r_intrinsics, cp.r_distortion_fisheye, cv::noArray(),
		    cp.r_intrinsics, image_size, CV_32FC1, *r_undistort_map_x,
		    *r_undistort_map_y);
	} else {
		cv::initUndistortRectifyMap(
		    cp.l_intrinsics, cp.l_distortion, cv::noArray(),
		    cp.l_intrinsics, image_size, CV_32FC1, *l_undistort_map_x,
		    *l_undistort_map_y);
		cv::initUndistortRectifyMap(
		    cp.r_intrinsics, cp.r_distortion, cv::noArray(),
		    cp.r_intrinsics, image_size, CV_32FC1, *r_undistort_map_x,
		    *r_undistort_map_y);
	}

	// Generate our rectification maps

	cv::initUndistortRectifyMap(
	    cp.l_intrinsics, zero_distortion, cp.l_rotation, cp.l_projection,
	    image_size, CV_32FC1, *l_rectify_map_x, *l_rectify_map_y);
	cv::initUndistortRectifyMap(
	    cp.r_intrinsics, zero_distortion, cp.r_rotation, cp.r_projection,
	    image_size, CV_32FC1, *r_rectify_map_x, *r_rectify_map_y);

	return true;
}

//! @todo Move this as it is a generic helper
static int
mkpath(char* path)
{
	char tmp[PATH_MAX]; //!< @todo PATH_MAX probably not strictly correct
	char* p = nullptr;
	size_t len;

	snprintf(tmp, sizeof(tmp), "%s", path);
	len = strlen(tmp) - 1;
	if (tmp[len] == '/') {
		tmp[len] = 0;
	}

	for (p = tmp + 1; *p; p++) {
		if (*p == '/') {
			*p = 0;
			if (mkdir(tmp, S_IRWXU) < 0 && errno != EEXIST)
				return -1;
			*p = '/';
		}
	}

	if (mkdir(tmp, S_IRWXU) < 0 && errno != EEXIST) {
		return -1;
	}

	return 0;
}

//! @todo Templatise?
XRT_MAYBE_UNUSED static float
cv_dist3d_point(cv::Point3f& p, cv::Point3f& q)
{
	cv::Point3f d = p - q;
	return cv::sqrt(d.x * d.x + d.y * d.y + d.z * d.z);
}

//! @todo Templatise?
XRT_MAYBE_UNUSED static float
cv_dist3d_vec(cv::Vec3f& p, cv::Vec3f& q)
{
	cv::Point3f d = p - q;
	return cv::sqrt(d.x * d.x + d.y * d.y + d.z * d.z);
}


#ifdef __cplusplus
}
#endif