diff --git a/requirements.txt b/requirements.txt
index 8b3e7ad..8f736a5 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -8,5 +8,5 @@ nbsphinx
 scipy
 opencv-contrib-python
 scikit-surgerycore
-scikit-surgeryimage
+scikit-surgeryimage>=0.7.4
 scikit-surgeryopencvcpp
\ No newline at end of file
diff --git a/setup.py b/setup.py
index 4c1f0a7..2253901 100644
--- a/setup.py
+++ b/setup.py
@@ -57,7 +57,7 @@
         'scipy',
         'opencv-contrib-python',
         'scikit-surgerycore',
-        'scikit-surgeryimage',
+        'scikit-surgeryimage>=0.7.4',
         'scikit-surgeryopencvcpp',
     ],
 
diff --git a/sksurgerycalibration/video/video_calibration_cost_functions.py b/sksurgerycalibration/video/video_calibration_cost_functions.py
index 3f667eb..55c238d 100644
--- a/sksurgerycalibration/video/video_calibration_cost_functions.py
+++ b/sksurgerycalibration/video/video_calibration_cost_functions.py
@@ -20,7 +20,7 @@ def stereo_2d_error(x_0,
                     l2r_tvec
                     ):
     """
-    Private method to RMSE cost function, in stereo, where x_0 contains
+    Private method to return vector of residuals, in stereo, where x_0 contains
     the left camera extrinsics.
     """
     rvecs = []
@@ -38,24 +38,22 @@ def stereo_2d_error(x_0,
         rvecs.append(rvec)
         tvecs.append(tvec)
 
-    tmp_sse, tmp_num = vm.compute_stereo_2d_err(l2r_rmat,
-                                                l2r_tvec,
-                                                common_object_points,
-                                                common_left_image_points,
-                                                left_intrinsics,
-                                                left_distortion,
-                                                common_object_points,
-                                                common_right_image_points,
-                                                right_intrinsics,
-                                                right_distortion,
-                                                rvecs,
-                                                tvecs
-                                                )
-
-    mse = tmp_sse / tmp_num
-    rmse = np.sqrt(mse)
-
-    return rmse
+    residual = vm.compute_stereo_2d_err(l2r_rmat,
+                                        l2r_tvec,
+                                        common_object_points,
+                                        common_left_image_points,
+                                        left_intrinsics,
+                                        left_distortion,
+                                        common_object_points,
+                                        common_right_image_points,
+                                        right_intrinsics,
+                                        right_distortion,
+                                        rvecs,
+                                        tvecs,
+                                        return_residuals=True
+                                        )
+
+    return residual
 
 
 def stereo_2d_and_3d_error(x_0,
diff --git a/sksurgerycalibration/video/video_calibration_driver_stereo.py b/sksurgerycalibration/video/video_calibration_driver_stereo.py
index c3d3c13..4a34be3 100644
--- a/sksurgerycalibration/video/video_calibration_driver_stereo.py
+++ b/sksurgerycalibration/video/video_calibration_driver_stereo.py
@@ -166,13 +166,7 @@ def iterative_calibration(self,
                               reference_ids,
                               reference_image_points,
                               reference_image_size,
-                              flags: int = cv2.CALIB_USE_INTRINSIC_GUESS,
-                              override_left_intrinsics=None,
-                              override_left_distortion=None,
-                              override_right_intrinsics=None,
-                              override_right_distortion=None,
-                              override_l2r_rmat=None,
-                              override_l2r_tvec=None
+                              flags: int = cv2.CALIB_USE_INTRINSIC_GUESS
                               ):
         """
         Does iterative calibration, like Datta 2009.
@@ -203,14 +197,7 @@ def iterative_calibration(self,
                 reference_image_size)
 
             proj_err, recon_err, param_copy = \
-                self.calibrate(flags,
-                               override_left_intrinsics,
-                               override_left_distortion,
-                               override_right_intrinsics,
-                               override_right_distortion,
-                               override_l2r_rmat,
-                               override_l2r_tvec
-                               )
+                self.calibrate(flags)
 
             LOGGER.info("Iterative calibration: %s: proj_err=%s, recon_err=%s.",
                         str(i), str(proj_err), str(recon_err))
diff --git a/sksurgerycalibration/video/video_calibration_metrics.py b/sksurgerycalibration/video/video_calibration_metrics.py
index 75b19ef..a3d7261 100644
--- a/sksurgerycalibration/video/video_calibration_metrics.py
+++ b/sksurgerycalibration/video/video_calibration_metrics.py
@@ -26,9 +26,10 @@ def compute_stereo_2d_err(l2r_rmat,
                           right_camera_matrix,
                           right_distortion,
                           left_rvecs,
-                          left_tvecs):
+                          left_tvecs,
+                          return_residuals=False):
     """
-    Function to compute stereo SSE re-projection error, over multiple views.
+    Function to compute stereo re-projection error, over multiple views.
 
     :param l2r_rmat: [3x3] ndarray, rotation for l2r transform
     :param l2r_tvec: [3x1] ndarray, translation for l2r transform
@@ -42,12 +43,15 @@ def compute_stereo_2d_err(l2r_rmat,
     :param right_distortion: [1x5] ndarray
     :param left_rvecs: Vector of [3x1] ndarray, Rodrigues rotations, left camera
     :param left_tvecs: Vector of [3x1] ndarray, translations, left camera
-    :return: SSE re-reprojection error, number_samples
+    :param return_residuals: if True returns vector of residuals for LM,
+    otherwise, returns SSE.
+    :return: re-reprojection error, number_samples
     """
     left_to_right = mu.construct_rigid_transformation(l2r_rmat, l2r_tvec)
 
     lse = 0
     rse = 0
+    residuals = []
     number_of_samples = 0
     number_of_frames = len(left_object_points)
 
@@ -72,18 +76,23 @@ def compute_stereo_2d_err(l2r_rmat,
                                                right_camera_matrix,
                                                right_distortion)
 
-        diff_left = left_image_points[i] - projected_left
-
-        lse = lse + np.sum(np.square(diff_left))
-
-        diff_right = right_image_points[i] - projected_right
-        rse = rse + np.sum(np.square(diff_right))
         number_of_samples = number_of_samples \
             + len(left_image_points[i]) \
             + len(right_image_points[i])
 
-    LOGGER.debug("Stereo RMS reprojection: left sse=%s, right sse=%s, num=%s",
-                 str(lse), str(rse), str(number_of_samples))
+        diff_left = left_image_points[i] - projected_left
+        diff_right = right_image_points[i] - projected_right
+
+        if return_residuals:
+            residuals.append(diff_left.reshape((-1)))
+            residuals.append(diff_right.reshape((-1)))
+        else:
+            lse = lse + np.sum(np.square(diff_left))
+            rse = rse + np.sum(np.square(diff_right))
+
+    if return_residuals:
+        return np.hstack(residuals)
+
     return lse + rse, number_of_samples
 
 
diff --git a/sksurgerycalibration/video/video_calibration_wrapper.py b/sksurgerycalibration/video/video_calibration_wrapper.py
index 72c5a95..8c31e9e 100644
--- a/sksurgerycalibration/video/video_calibration_wrapper.py
+++ b/sksurgerycalibration/video/video_calibration_wrapper.py
@@ -6,7 +6,7 @@
 from typing import List
 import numpy as np
 import cv2
-from scipy.optimize import minimize
+from scipy.optimize import least_squares
 import sksurgerycore.transforms.matrix as skcm
 import sksurgerycalibration.video.video_calibration_utils as vu
 import sksurgerycalibration.video.video_calibration_metrics as vm
@@ -111,21 +111,66 @@ def stereo_video_calibration(left_ids,
     :param flags: OpenCV flags to pass to calibrateCamera().
     :return:
     """
-    # Calibrate left, using all available points
-    l_rms, l_c, l_d, l_rvecs, l_tvecs \
-        = cv2.calibrateCamera(left_object_points,
-                              left_image_points,
-                              image_size,
-                              None, None)
 
-    # Calibrate right using all available points.
-    r_rms, r_c, r_d, r_rvecs, r_tvecs \
-        = cv2.calibrateCamera(right_object_points,
-                              right_image_points,
-                              image_size,
-                              None, None)
+    # We only do override if all override params are specified.
+    # pylint:disable=too-many-boolean-expressions
+    do_override = False
+    if override_left_intrinsics is not None \
+        and override_left_distortion is not None \
+        and override_right_intrinsics is not None \
+        and override_right_distortion is not None \
+        and override_l2r_rmat is not None \
+        and override_l2r_tvec is not None:
+
+        do_override = True
 
-    # But for stereo, OpenCV needs common points.
+        l_c = override_left_intrinsics
+        l_d = override_left_distortion
+        r_c = override_right_intrinsics
+        r_d = override_right_distortion
+
+    number_of_frames = len(left_object_points)
+
+    l_rvecs = []
+    l_tvecs = []
+    r_rvecs = []
+    r_tvecs = []
+
+    if do_override:
+
+        for i in range(0, number_of_frames):
+
+            _, rvecs, tvecs = cv2.solvePnP(
+                left_object_points[i],
+                left_image_points[i],
+                l_c,
+                l_d)
+            l_rvecs.append(rvecs)
+            l_tvecs.append(tvecs)
+
+            _, rvecs, tvecs = cv2.solvePnP(
+                right_object_points[i],
+                right_image_points[i],
+                r_c,
+                r_d)
+            r_rvecs.append(rvecs)
+            r_tvecs.append(tvecs)
+
+    else:
+
+        _, l_c, l_d, l_rvecs, l_tvecs \
+            = cv2.calibrateCamera(left_object_points,
+                                  left_image_points,
+                                  image_size,
+                                  None, None)
+
+        _, r_c, r_d, r_rvecs, r_tvecs \
+            = cv2.calibrateCamera(right_object_points,
+                                  right_image_points,
+                                  image_size,
+                                  None, None)
+
+    # For stereo, OpenCV needs common points.
     _, common_object_points, common_left_image_points, \
         common_right_image_points \
         = vu.filter_common_points_all_images(left_ids,
@@ -134,72 +179,100 @@ def stereo_video_calibration(left_ids,
                                              right_ids,
                                              right_image_points, 10)
 
-    # First do stereo calibration, using fixed intrinsics.
-    s_rms, l_c, l_d, r_c, r_d, \
-        l2r_r, l2r_t, essential, fundamental = cv2.stereoCalibrate(
-            common_object_points,
-            common_left_image_points,
-            common_right_image_points,
-            l_c,
-            l_d,
-            r_c,
-            r_d,
-            image_size,
-            flags=cv2.CALIB_USE_INTRINSIC_GUESS | cv2.CALIB_FIX_INTRINSIC)
-
-    # Then do it again, using the passed in flags.
-    s_rms, l_c, l_d, r_c, r_d, \
-        l2r_r, l2r_t, essential, fundamental = cv2.stereoCalibrate(
-            common_object_points,
-            common_left_image_points,
-            common_right_image_points,
-            l_c,
-            l_d,
-            r_c,
-            r_d,
-            image_size,
-            flags=flags)
+    if do_override:
 
-    # pylint:disable=too-many-boolean-expressions
-    if override_left_intrinsics is not None \
-        and override_left_distortion is not None \
-        and override_right_intrinsics is not None \
-        and override_right_distortion is not None \
-        and override_l2r_rmat is not None \
-            and override_l2r_tvec is not None:
+        # Do OpenCV stereo calibration, using override intrinsics,
+        # just so we can get the essential and fundamental matrix out.
+        _, l_c, l_d, r_c, r_d, \
+            l2r_r, l2r_t, essential, fundamental = cv2.stereoCalibrate(
+                common_object_points,
+                common_left_image_points,
+                common_right_image_points,
+                l_c,
+                l_d,
+                r_c,
+                r_d,
+                image_size,
+                flags=cv2.CALIB_USE_INTRINSIC_GUESS | cv2.CALIB_FIX_INTRINSIC)
+
+        l2r_r = override_l2r_rmat
+        l2r_t = override_l2r_tvec
+
+        assert np.allclose(l_c, override_left_intrinsics)
+        assert np.allclose(l_d, override_left_distortion)
+        assert np.allclose(r_c, override_right_intrinsics)
+        assert np.allclose(r_d, override_right_distortion)
+
+    else:
+
+        # Do OpenCV stereo calibration, using intrinsics from OpenCV mono.
+        _, l_c, l_d, r_c, r_d, \
+            l2r_r, l2r_t, essential, fundamental = cv2.stereoCalibrate(
+                common_object_points,
+                common_left_image_points,
+                common_right_image_points,
+                l_c,
+                l_d,
+                r_c,
+                r_d,
+                image_size,
+                flags=cv2.CALIB_USE_INTRINSIC_GUESS | cv2.CALIB_FIX_INTRINSIC)
+
+        # Then do it again, using the passed in flags.
+        _, l_c, l_d, r_c, r_d, \
+            l2r_r, l2r_t, essential, fundamental = cv2.stereoCalibrate(
+                common_object_points,
+                common_left_image_points,
+                common_right_image_points,
+                l_c,
+                l_d,
+                r_c,
+                r_d,
+                image_size,
+                flags=flags)
+
+    if do_override:
 
         # Stereo calibration is hard for a laparoscope.
         # In clinical practice, the data may be way too variable.
         # For stereo scopes, they are often fixed focus,
         # i.e. fixed intrinsics, and fixed stereo.
         # So, we may prefer to just do the best possible calibration
-        # in the lab, and then fix it.
+        # in the lab, and then keep those values constant.
         # But we then would still want to optimise the camera extrinsics
         # as the camera poses directly affect the hand-eye calibration.
-        s_reproj, l_rvecs, l_tvecs, \
+
+        _, l_rvecs, l_tvecs, \
             = stereo_calibration_extrinsics(
                 common_object_points,
                 common_left_image_points,
                 common_right_image_points,
                 l_rvecs,
                 l_tvecs,
-                override_left_intrinsics,
-                override_left_distortion,
-                override_right_intrinsics,
-                override_right_distortion,
-                override_l2r_rmat,
-                override_l2r_tvec
+                l_c,
+                l_d,
+                r_c,
+                r_d,
+                l2r_r,
+                l2r_t
             )
 
-    # And recompute rvecs and tvecs, consistently, given new l2r params.
-    number_of_frames = len(left_object_points)
+    else:
+
+        # Normal OpenCV stereo calibration optimises intrinsics,
+        # distortion, and stereo parameters, but doesn't output pose.
+        # So here, we recompute the left camera pose.
+        for i in range(0, number_of_frames):
+            _, l_rvecs[i], l_tvecs[i] = cv2.solvePnP(
+                common_object_points[i],
+                common_left_image_points[i],
+                l_c,
+                l_d)
+
+    # Here, we are computing the right hand side rvecs and tvecs
+    # given the new left hand side rvecs, tvecs and the l2r.
     left_to_right = skcm.construct_rigid_transformation(l2r_r, l2r_t)
     for i in range(0, number_of_frames):
-        _, l_rvecs[i], l_tvecs[i] = cv2.solvePnP(
-            common_object_points[i],
-            common_left_image_points[i],
-            l_c,
-            l_d)
         left_chessboard_to_camera = \
             vu.extrinsic_vecs_to_matrix(l_rvecs[i], l_tvecs[i])
         right_chessboard_to_camera = \
@@ -244,8 +317,8 @@ def stereo_video_calibration(left_ids,
     mse = sse / num_samples
     s_recon = np.sqrt(mse)
 
-    LOGGER.info("Stereo Calib: l=%s, r=%s, opencv=%s, proj=%s, recon=%s",
-                str(l_rms), str(r_rms), str(s_rms), str(s_reproj), str(s_recon))
+    LOGGER.info("Stereo Calib: proj=%s, recon=%s",
+                str(s_reproj), str(s_recon))
 
     return s_reproj, s_recon, \
         l_c, l_d, l_rvecs, l_tvecs, \
@@ -470,21 +543,21 @@ def stereo_calibration_extrinsics(common_object_points,
         x_0[i * 6 + 4] = l_tvecs[i][1]
         x_0[i * 6 + 5] = l_tvecs[i][2]
 
-    res = minimize(vcf.stereo_2d_error, x_0,
-                   args=(common_object_points,
-                         common_left_image_points,
-                         common_right_image_points,
-                         override_left_intrinsics,
-                         override_left_distortion,
-                         override_right_intrinsics,
-                         override_right_distortion,
-                         override_l2r_rmat,
-                         override_l2r_tvec
-                         ),
-                   method='Powell',
-                   tol=1e-2,
-                   options={'disp': False, 'maxiter': 10000})
-
+    res = least_squares(vcf.stereo_2d_error, x_0,
+                        args=(common_object_points,
+                              common_left_image_points,
+                              common_right_image_points,
+                              override_left_intrinsics,
+                              override_left_distortion,
+                              override_right_intrinsics,
+                              override_right_distortion,
+                              override_l2r_rmat,
+                              override_l2r_tvec),
+                        method='lm',
+                        x_scale='jac',
+                        verbose=0)
+
+    LOGGER.info("Stereo Re-Calibration: status=%s", str(res.status))
     LOGGER.info("Stereo Re-Calibration: success=%s", str(res.success))
     LOGGER.info("Stereo Re-Calibration: msg=%s", str(res.message))
 
diff --git a/tests/data/2020_01_20_storz/pattern_4x4_19x26_5_4_with_inset_9x14.png b/tests/data/2020_01_20_storz/pattern_4x4_19x26_5_4_with_inset_9x14.png
new file mode 100644
index 0000000..720b2f9
Binary files /dev/null and b/tests/data/2020_01_20_storz/pattern_4x4_19x26_5_4_with_inset_9x14.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/calib.left.distortion.txt b/tests/data/laparoscope_calibration/cbh-viking/calib.left.distortion.txt
new file mode 100755
index 0000000..5d33916
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/calib.left.distortion.txt
@@ -0,0 +1 @@
+-0.291690 -0.001882 0.007161 -0.000171 0.374519
\ No newline at end of file
diff --git a/tests/data/laparoscope_calibration/cbh-viking/calib.left.intrinsics.txt b/tests/data/laparoscope_calibration/cbh-viking/calib.left.intrinsics.txt
new file mode 100755
index 0000000..f47de1e
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/calib.left.intrinsics.txt
@@ -0,0 +1,3 @@
+1766.276290 0.000000 915.665775
+0.000000 1769.623383 458.985368
+0.000000 0.000000 1.000000
\ No newline at end of file
diff --git a/tests/data/laparoscope_calibration/cbh-viking/calib.right.distortion.txt b/tests/data/laparoscope_calibration/cbh-viking/calib.right.distortion.txt
new file mode 100755
index 0000000..2b6657f
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/calib.right.distortion.txt
@@ -0,0 +1 @@
+-0.291115 0.226945 -0.000367 0.013965 -0.121846
\ No newline at end of file
diff --git a/tests/data/laparoscope_calibration/cbh-viking/calib.right.intrinsics.txt b/tests/data/laparoscope_calibration/cbh-viking/calib.right.intrinsics.txt
new file mode 100755
index 0000000..e47abdb
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/calib.right.intrinsics.txt
@@ -0,0 +1,3 @@
+1792.669020 0.000000 1113.645820
+0.000000 1792.169495 478.497416
+0.000000 0.000000 1.000000
\ No newline at end of file
diff --git a/tests/data/laparoscope_calibration/cbh-viking/config-cbh-dots.json b/tests/data/laparoscope_calibration/cbh-viking/config-cbh-dots.json
new file mode 100644
index 0000000..2987bf4
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/config-cbh-dots.json
@@ -0,0 +1,52 @@
+{
+    "tracker": {
+        "tracker type": "unit test",
+        "use quaternions": false,
+        "tracked objects": {
+            "marker": "config/8700339.rom",
+            "laparoscope": "config/8700449.rom",
+            "pointer": "config/8700340.rom"
+        }
+    },
+    "calibration": {
+        "general": {
+            "load previous calibration file": true,
+            "left intrinsics": "",
+            "left distortion": "",
+            "right intrinsics": "",
+            "right distortion": "",
+            "l2r": "",
+            "features": "dots",
+            "frames required": 5,
+            "smooth images": false,
+            "iterative": false,
+            "maximum reprojection error": 20,
+            "maximum reconstruction error": 5,
+            "display good or bad": true,
+            "required to pass": false
+        },
+        "charuco": {
+            "minimum points per frame": 50,
+            "squares": [19, 26],
+            "square sizes": [5, 4],
+            "chessboard squares": [9, 14],
+            "chessboard square size": 3,
+            "filter markers": false,
+            "error if no chessboard": true,
+            "error if no charuco": false
+        },
+        "dots": {
+            "intrinsic params": "tests/data/calibration/cbh-viking/calib.left.intrinsics.txt",
+            "distortion coeffs": "tests/data/calibration/cbh-viking/calib.left.distortion.txt",
+            "minimum points per frame": 36,
+            "dots": [14, 16],
+            "separation in mm": 4,
+            "fiducial indexes": [69, 74, 149, 154],
+            "reference image size in pixels": [1200, 1360],
+            "pixels per mm": 80
+        }
+    },
+    "recording": {
+        "output dir": "output/"
+    }
+}
\ No newline at end of file
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_08_32/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_08_32/left_image.png
new file mode 100755
index 0000000..928ada6
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_08_32/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_08_32/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_08_32/right_image.png
new file mode 100755
index 0000000..fc62e8e
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_08_32/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_08_32/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_08_32/tracking_data.txt
new file mode 100755
index 0000000..7253347
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_08_32/tracking_data.txt
@@ -0,0 +1,4 @@
+-0.982398 -0.164113 -0.089220 72.810715
+-0.008690 0.517266 -0.855780 -263.958832
+0.186595 -0.839942 -0.509588 -1396.689209
+0.000000 0.000000 0.000000 1.000000
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_09_35/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_09_35/left_image.png
new file mode 100755
index 0000000..595821a
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_09_35/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_09_35/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_09_35/right_image.png
new file mode 100755
index 0000000..90dc420
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_09_35/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_09_35/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_09_35/tracking_data.txt
new file mode 100755
index 0000000..e0a6823
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_09_35/tracking_data.txt
@@ -0,0 +1,4 @@
+-0.982717 -0.162246 -0.089131 72.787117
+-0.007737 0.517065 -0.855911 -263.931549
+0.184955 -0.840428 -0.509384 -1396.719971
+0.000000 0.000000 0.000000 1.000000
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_22/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_22/left_image.png
new file mode 100755
index 0000000..19283d6
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_22/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_22/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_22/right_image.png
new file mode 100755
index 0000000..684b189
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_22/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_22/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_22/tracking_data.txt
new file mode 100755
index 0000000..ec75519
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_22/tracking_data.txt
@@ -0,0 +1,4 @@
+-0.982798 -0.161738 -0.089161 72.783470
+-0.007532 0.517470 -0.855668 -263.936035
+0.184533 -0.840277 -0.509786 -1396.716064
+0.000000 0.000000 0.000000 1.000000
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_45/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_45/left_image.png
new file mode 100755
index 0000000..f1607ef
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_45/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_45/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_45/right_image.png
new file mode 100755
index 0000000..490886b
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_45/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_45/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_45/tracking_data.txt
new file mode 100755
index 0000000..77ce890
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_10_45/tracking_data.txt
@@ -0,0 +1,4 @@
+-0.982774 -0.161856 -0.089202 72.792496
+-0.007553 0.517448 -0.855681 -263.932983
+0.184655 -0.840268 -0.509757 -1396.728027
+0.000000 0.000000 0.000000 1.000000
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_22/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_22/left_image.png
new file mode 100755
index 0000000..3e3bf45
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_22/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_22/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_22/right_image.png
new file mode 100755
index 0000000..1f35410
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_22/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_22/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_22/tracking_data.txt
new file mode 100755
index 0000000..0f5014c
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_22/tracking_data.txt
@@ -0,0 +1,4 @@
+nan nan nan nan
+nan nan nan nan
+nan nan nan nan
+nan nan nan nan
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_56/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_56/left_image.png
new file mode 100755
index 0000000..91fbb5e
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_56/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_56/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_56/right_image.png
new file mode 100755
index 0000000..c877310
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_56/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_56/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_56/tracking_data.txt
new file mode 100755
index 0000000..17f8e8a
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_11_56/tracking_data.txt
@@ -0,0 +1,4 @@
+-0.982902 -0.161179 -0.089024 72.783546
+-0.007396 0.517651 -0.855560 -263.924164
+0.183982 -0.840273 -0.509992 -1396.731201
+0.000000 0.000000 0.000000 1.000000
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_04/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_04/left_image.png
new file mode 100755
index 0000000..aa77fff
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_04/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_04/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_04/right_image.png
new file mode 100755
index 0000000..c113175
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_04/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_04/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_04/tracking_data.txt
new file mode 100755
index 0000000..b9b4797
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_04/tracking_data.txt
@@ -0,0 +1,4 @@
+-0.982862 -0.161351 -0.089152 72.793602
+-0.007386 0.517705 -0.855527 -263.921356
+0.184194 -0.840207 -0.510024 -1396.717651
+0.000000 0.000000 0.000000 1.000000
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_24/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_24/left_image.png
new file mode 100755
index 0000000..633feee
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_24/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_24/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_24/right_image.png
new file mode 100755
index 0000000..ef8adbd
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_24/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_24/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_24/tracking_data.txt
new file mode 100755
index 0000000..29daf82
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_24/tracking_data.txt
@@ -0,0 +1,4 @@
+-0.982902 -0.161175 -0.089025 72.777924
+-0.007394 0.517654 -0.855558 -263.921570
+0.183979 -0.840272 -0.509995 -1396.695679
+0.000000 0.000000 0.000000 1.000000
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_44/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_44/left_image.png
new file mode 100755
index 0000000..f6352aa
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_44/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_44/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_44/right_image.png
new file mode 100755
index 0000000..be6f952
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_44/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_44/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_44/tracking_data.txt
new file mode 100755
index 0000000..3787ccb
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_12_44/tracking_data.txt
@@ -0,0 +1,4 @@
+-0.982908 -0.161018 -0.089251 72.785416
+-0.007027 0.517258 -0.855801 -263.899078
+0.183965 -0.840546 -0.509548 -1396.661499
+0.000000 0.000000 0.000000 1.000000
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_18/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_18/left_image.png
new file mode 100755
index 0000000..1c5a70e
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_18/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_18/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_18/right_image.png
new file mode 100755
index 0000000..489e920
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_18/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_18/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_18/tracking_data.txt
new file mode 100755
index 0000000..2663706
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_18/tracking_data.txt
@@ -0,0 +1,4 @@
+-0.974732 -0.205281 -0.088079 72.982742
+-0.031747 0.517605 -0.855030 -264.551239
+0.221111 -0.830629 -0.511043 -1395.835815
+0.000000 0.000000 0.000000 1.000000
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_46/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_46/left_image.png
new file mode 100755
index 0000000..0fe5968
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_46/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_46/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_46/right_image.png
new file mode 100755
index 0000000..888c18a
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_46/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_46/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_46/tracking_data.txt
new file mode 100755
index 0000000..4349e97
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_13_46/tracking_data.txt
@@ -0,0 +1,4 @@
+-0.976352 -0.197388 -0.088175 72.941139
+-0.027534 0.518080 -0.854889 -264.480377
+0.214426 -0.832245 -0.511263 -1395.980469
+0.000000 0.000000 0.000000 1.000000
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_26/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_26/left_image.png
new file mode 100755
index 0000000..6f3b1db
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_26/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_26/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_26/right_image.png
new file mode 100755
index 0000000..5235735
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_26/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_26/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_26/tracking_data.txt
new file mode 100755
index 0000000..0a449cc
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_26/tracking_data.txt
@@ -0,0 +1,4 @@
+-0.976963 -0.194236 -0.088409 72.939697
+-0.025577 0.517852 -0.855088 -264.430023
+0.211872 -0.833127 -0.510891 -1396.021362
+0.000000 0.000000 0.000000 1.000000
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_58/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_58/left_image.png
new file mode 100755
index 0000000..46c9dc4
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_58/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_58/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_58/right_image.png
new file mode 100755
index 0000000..2900a2b
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_58/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_58/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_58/tracking_data.txt
new file mode 100755
index 0000000..e3884f9
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_14_58/tracking_data.txt
@@ -0,0 +1,4 @@
+-0.977317 -0.192506 -0.088278 72.926239
+-0.024757 0.517827 -0.855127 -264.402130
+0.210330 -0.833545 -0.510847 -1396.077759
+0.000000 0.000000 0.000000 1.000000
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_16_59/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_16_59/left_image.png
new file mode 100755
index 0000000..54184c1
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_16_59/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_16_59/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_16_59/right_image.png
new file mode 100755
index 0000000..638e31c
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_16_59/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_16_59/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_16_59/tracking_data.txt
new file mode 100755
index 0000000..3e355fc
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_16_59/tracking_data.txt
@@ -0,0 +1,4 @@
+-0.978301 -0.188249 -0.086541 74.033569
+-0.024157 0.518483 -0.854746 -265.486938
+0.205775 -0.834109 -0.511780 -1396.832520
+0.000000 0.000000 0.000000 1.000000
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_17_36/left_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_17_36/left_image.png
new file mode 100755
index 0000000..c132d64
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_17_36/left_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_17_36/right_image.png b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_17_36/right_image.png
new file mode 100755
index 0000000..4644713
Binary files /dev/null and b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_17_36/right_image.png differ
diff --git a/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_17_36/tracking_data.txt b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_17_36/tracking_data.txt
new file mode 100755
index 0000000..c35112c
--- /dev/null
+++ b/tests/data/laparoscope_calibration/cbh-viking/snapshots-metal-1/14_17_36/tracking_data.txt
@@ -0,0 +1,4 @@
+-0.979023 -0.184886 -0.085623 74.031738
+-0.023645 0.520491 -0.853539 -265.775879
+0.202373 -0.833610 -0.513945 -1396.724243
+0.000000 0.000000 0.000000 1.000000
diff --git a/tests/video/test_charuco_plus_chessboard.py b/tests/video/test_charuco_plus_chessboard.py
index 94bbcdf..86b0c72 100644
--- a/tests/video/test_charuco_plus_chessboard.py
+++ b/tests/video/test_charuco_plus_chessboard.py
@@ -31,8 +31,11 @@ def test_stereo_davinci():
         right_images.append(image)
     assert (len(right_images) == 59)
 
+    ref_img = cv2.imread('tests/data/2020_01_20_storz/pattern_4x4_19x26_5_4_with_inset_9x14.png')
+
     minimum_number_of_points_per_image = 50
-    detector = pd.CharucoPlusChessboardPointDetector(error_if_no_chessboard=False) # Try to accept as many as possible.
+    detector = pd.CharucoPlusChessboardPointDetector(ref_img,
+                                                     error_if_no_chessboard=False) # Try to accept as many as possible.
     calibrator = sc.StereoVideoCalibrationDriver(detector, minimum_number_of_points_per_image)
     for i, _ in enumerate(left_images):
         try:
diff --git a/tests/video/test_chessboard_calibration.py b/tests/video/test_chessboard_calibration.py
index e42cfc4..2fb239e 100644
--- a/tests/video/test_chessboard_calibration.py
+++ b/tests/video/test_chessboard_calibration.py
@@ -142,11 +142,12 @@ def test_chessboard_stereo():
     reproj_err, recon_err, params = calibrator.calibrate()
 
     # Just for a regression test, checking reprojection error, and recon error.
+    print("\nStereo, default=" + str(reproj_err) + ", " + str(recon_err))
     assert reproj_err < 0.7
-    assert recon_err < 1.8
-    print("Stereo, default=" + str(reproj_err) + ", " + str(recon_err))
+    assert recon_err < 1.7
 
-    # Now test rerunning where we optimize the extrinsics with other params fixed.
+    # Test running with fixed intrinsics and fixed stereo, using existing
+    # calibration parameters, thereby re-optimising the camera poses.
     reproj_err, recon_err, params = \
         calibrator.calibrate(
             override_left_intrinsics=params.left_params.camera_matrix,
@@ -157,9 +158,10 @@ def test_chessboard_stereo():
             override_l2r_tvec=params.l2r_tvec
         )
 
+    # The above re-optimisation shouldn't make things worse, as its using same intrinsics and stereo.
+    print("Stereo, re-optimise=" + str(reproj_err) + ", " + str(recon_err))
     assert reproj_err < 0.7
-    assert recon_err < 1.8
-    print("Stereo, extrinsics=" + str(reproj_err) + ", " + str(recon_err))
+    assert recon_err < 1.7
 
     # Test iterative calibration.
     reference_ids, reference_points, reference_image_size = get_iterative_reference_data()
@@ -168,6 +170,38 @@ def test_chessboard_stereo():
                                                                      reference_ids,
                                                                      reference_points,
                                                                      reference_image_size)
+    print("Stereo, iterative=" + str(reproj_err) + ", " + str(recon_err))
     assert reproj_err < 0.7
     assert recon_err < 1.6
-    print("Stereo, iterative=" + str(reproj_err) + ", " + str(recon_err))
+
+    # Now test re-optimising extrinsics, using a completely different set of calibration params.
+    ov_l_c = np.loadtxt('tests/data/laparoscope_calibration/cbh-viking/calib.left.intrinsics.txt')
+    ov_l_d = np.loadtxt('tests/data/laparoscope_calibration/cbh-viking/calib.left.distortion.txt')
+    ov_r_c = np.loadtxt('tests/data/laparoscope_calibration/cbh-viking/calib.right.intrinsics.txt')
+    ov_r_d = np.loadtxt('tests/data/laparoscope_calibration/cbh-viking/calib.right.distortion.txt')
+
+    ov_l2r_t = np.zeros((3, 1))
+    ov_l2r_t[0][0] = -4.5
+
+    reproj_err, recon_err, params = \
+        calibrator.calibrate(
+            override_left_intrinsics=ov_l_c,
+            override_left_distortion=ov_l_d,
+            override_right_intrinsics=ov_r_c,
+            override_right_distortion=ov_r_d,
+            override_l2r_rmat=np.eye(3),
+            override_l2r_tvec=ov_l2r_t
+        )
+
+    # Must check that the overrides have actually been set on the output.
+    assert np.allclose(params.left_params.camera_matrix, ov_l_c)
+    assert np.allclose(params.left_params.dist_coeffs, ov_l_d)
+    assert np.allclose(params.right_params.camera_matrix, ov_r_c)
+    assert np.allclose(params.right_params.dist_coeffs, ov_r_d)
+    assert np.allclose(params.l2r_rmat, np.eye(3))
+    assert np.allclose(params.l2r_tvec, ov_l2r_t)
+
+    # Not expecting good results, as the camera parameters are completely wrong.
+    print("Stereo, override=" + str(reproj_err) + ", " + str(recon_err))
+    assert reproj_err < 33
+    assert recon_err < 109
diff --git a/tests/video/test_hand_eye.py b/tests/video/test_hand_eye.py
index cad989b..9e04438 100644
--- a/tests/video/test_hand_eye.py
+++ b/tests/video/test_hand_eye.py
@@ -67,6 +67,9 @@ def test_handeye_calibration_mono():
     obj_tracking = load_tracking_from_glob(
         'tests/data/2020_01_20_storz/12_50_30/calib.calib_obj_tracking.*.txt')
 
+    ref_img = cv2.imread(
+        'tests/data/2020_01_20_storz/pattern_4x4_19x26_5_4_with_inset_9x14.png')
+
     assert len(images) == 10
 
     assert len(device_tracking) == 10
@@ -74,7 +77,8 @@ def test_handeye_calibration_mono():
 
     min_number_of_points_per_image = 50
     detector = \
-        chpd.CharucoPlusChessboardPointDetector(error_if_no_chessboard=False)
+        chpd.CharucoPlusChessboardPointDetector(ref_img,
+                                                error_if_no_chessboard=False)
 
     calibrator = \
         vidcal.video_calibration_driver_mono.MonoVideoCalibrationDriver(
@@ -122,6 +126,9 @@ def test_handeye_calibration_stereo():
     obj_tracking = load_tracking_from_glob(
         'tests/data/2020_01_20_storz/12_50_30/calib.calib_obj_tracking.*.txt')
 
+    ref_img = cv2.imread(
+        'tests/data/2020_01_20_storz/pattern_4x4_19x26_5_4_with_inset_9x14.png')
+
     assert len(left_images) == 10
     assert len(right_images) == 10
     assert len(device_tracking) == 10
@@ -129,7 +136,8 @@ def test_handeye_calibration_stereo():
 
     min_number_of_points_per_image = 50
     detector = \
-        chpd.CharucoPlusChessboardPointDetector(charuco_filtering=True,
+        chpd.CharucoPlusChessboardPointDetector(ref_img,
+                                                charuco_filtering=True,
                                                 error_if_no_chessboard=False)
 
     calibrator = \