After successful calibration with charuco board, I do see the images in the Dataset folder. However, we contninure to see the following error message. What does it mean and how we can fix it?

We used this command for our OAK-D-Lite: python calibrate.py -s 2.35 -brd OAK-D-LITE -db

gray = cv2.cvtColor(frame, cv2.COLOR_BGR2GRAY)
cv2.error: OpenCV(4.5.5) D:\a\opencv-python\opencv-python\opencv\modules\imgproc\src\color.cpp:182: error: (-215:Assertion failed) !_src.empty() in function 'cv::cvtColor'

  • erik replied to this.

    Hi JamesYeh ,
    Which commit are you using of the depthai repo (where calibrate.py is located)? Are you using latest? Which depthai version are you using?
    Thanks, Erik

      Here is the command we use: python calibrate.py -s 2.45 -brd OAK-D-LITE -db
      We eventually got t finish the calibration process, but at the end with an Eipolar number. The screen showed red background image with text "EEprom Write Failed!! 0.144 Try recalibrating!! We tried a few more times for calibration but the same outcome showing EEprom Write error.

      • erik replied to this.

        JamesYeh could you share the images that you took while calibrating? I believe they are written in /dataset folder. I would assume images for calibration weren't taken ideally which results in bad epipolar error and failed calibration.
        Thanks, Erik

          JamesYeh

          Can you share a clear image of the calibration board? Just want to see if it has any defects. Also, can you double-check the square and marker size?

            Here are 3 up-to-date scanned images and cardboard image. I tried many times and it still showed EEprom Write failed message. I'm wondering if this is due to hardware setting issues instead of calibration procedure. I used the command in the following for OAK_D Lite and the square size is 2.45 cm. Thanks!
            python calibrate.py -s 2.45 -brd OAK-D-LITE -db



              JamesYeh

              Might be the quality of the calibration board (as you glued it to the carton board, some dents may have formed, it's also very glossy), can you try to calibrate using a monitor to show the Calib board? Or to print a better board?

                @JamesYeh what version of depthai you have installed? Do you have other depthai devices, and if so, do you see the same calibration error for them?

                It's the latest version we downloaded from your website recently.

                  JamesYeh in the depthai/resources/ there should be export of the calibration file called <your_cam_mxid.json>. Can you find it and share it with us?

                    Is this one?

                    {
                    "board_config":
                    {
                    "name": "OAK-D-LITE",
                    "revision": "R0M0E0",
                    "left_fov_deg": 72.9,
                    "rgb_fov_deg": 68.7938,
                    "left_to_right_distance_cm": 7.5,
                    "left_to_rgb_distance_cm": 3.75
                    }
                    }

                    Or this one?

                    {
    "batchName": "",
    "batchTime": 0,
    "boardConf": "",
    "boardCustom": "",
    "boardName": "OAK-D-LITE",
    "boardOptions": 0,
    "boardRev": "R0M0E0",
    "cameraData": [
        [
            1,
            {
                "cameraType": 0,
                "distortionCoeff": [
                    72.98009490966797,
                    522.8361206054688,
                    0.002551776124164462,
                    -0.0023029004223644733,
                    -295.53253173828125,
                    73.34515380859375,
                    515.9074096679688,
                    -263.6693115234375,
                    0.0,
                    0.0,
                    0.0,
                    0.0,
                    0.0,
                    0.0
                ],
                "extrinsics": {
                    "rotationMatrix": [
                        [
                            0.999978244304657,
                            -0.004396865144371986,
                            -0.004916712641716003
                        ],
                        [
                            0.004408243577927351,
                            0.9999876022338867,
                            0.002305838745087385
                        ],
                        [
                            0.004906513262540102,
                            -0.0023274626582860947,
                            0.9999852776527405
                        ]
                    ],
                    "specTranslation": {
                        "x": -7.5,
                        "y": 0.0,
                        "z": 0.0
                    },
                    "toCameraSocket": 2,
                    "translation": {
                        "x": -7.507689476013184,
                        "y": -0.0775049552321434,
                        "z": -0.2214062213897705
                    }
                },
                "height": 480,
                "intrinsicMatrix": [
                    [
                        457.5869140625,
                        0.0,
                        326.1402282714844
                    ],
                    [
                        0.0,
                        458.2024841308594,
                        228.6510009765625
                    ],
                    [
                        0.0,
                        0.0,
                        1.0
                    ]
                ],
                "lensPosition": 0,
                "specHfovDeg": 72.9000015258789,
                "width": 640
            }
        ],
        [
            2,
            {
                "cameraType": 0,
                "distortionCoeff": [
                    17.46405601501465,
                    -150.1464385986328,
                    -0.0016553334426134825,
                    0.00011951004853472114,
                    273.1391906738281,
                    17.549184799194336,
                    -150.72332763671875,
                    274.1268005371094,
                    0.0,
                    0.0,
                    0.0,
                    0.0,
                    0.0,
                    0.0
                ],
                "extrinsics": {
                    "rotationMatrix": [
                        [
                            0.9999249577522278,
                            0.008298547938466072,
                            -0.009012527763843536
                        ],
                        [
                            -0.008360672742128372,
                            0.9999414086341858,
                            -0.00687749870121479
                        ],
                        [
                            0.008954926393926144,
                            0.006952333729714155,
                            0.9999357461929321
                        ]
                    ],
                    "specTranslation": {
                        "x": 3.75,
                        "y": 0.0,
                        "z": 0.0
                    },
                    "toCameraSocket": 0,
                    "translation": {
                        "x": 3.6784276962280273,
                        "y": -0.0021816904190927744,
                        "z": -0.033592239022254944
                    }
                },
                "height": 480,
                "intrinsicMatrix": [
                    [
                        453.6978454589844,
                        0.0,
                        305.2757873535156
                    ],
                    [
                        0.0,
                        454.0751037597656,
                        235.96502685546875
                    ],
                    [
                        0.0,
                        0.0,
                        1.0
                    ]
                ],
                "lensPosition": 0,
                "specHfovDeg": 72.9000015258789,
                "width": 640
            }
        ],
        [
            0,
            {
                "cameraType": 0,
                "distortionCoeff": [
                    75.20023345947266,
                    -32.183929443359375,
                    0.00032048311550170183,
                    0.0047751059755682945,
                    243.44769287109375,
                    75.53861999511719,
                    -41.4549560546875,
                    256.639404296875,
                    0.0,
                    0.0,
                    0.0,
                    0.0,
                    0.0,
                    0.0
                ],
                "extrinsics": {
                    "rotationMatrix": [],
                    "specTranslation": {
                        "x": 0.0,
                        "y": 0.0,
                        "z": 0.0
                    },
                    "toCameraSocket": -1,
                    "translation": {
                        "x": 0.0,
                        "y": 0.0,
                        "z": 0.0
                    }
                },
                "height": 1080,
                "intrinsicMatrix": [
                    [
                        1493.9559326171875,
                        0.0,
                        1033.2745361328125
                    ],
                    [
                        0.0,
                        1490.411865234375,
                        514.8790893554688
                    ],
                    [
                        0.0,
                        0.0,
                        1.0
                    ]
                ],
                "lensPosition": 135,
                "specHfovDeg": 68.7938003540039,
                "width": 1920
            }
        ]
    ],
    "hardwareConf": "",
    "imuExtrinsics": {
        "rotationMatrix": [],
        "specTranslation": {
            "x": 0.0,
            "y": 0.0,
            "z": 0.0
        },
        "toCameraSocket": -1,
        "translation": {
            "x": 0.0,
            "y": 0.0,
            "z": 0.0
        }
    },
    "miscellaneousData": [],
    "productName": "",
    "stereoRectificationData": {
        "leftCameraSocket": 1,
        "rectifiedRotationLeft": [
            [
                0.9996805787086487,
                0.005854921415448189,
                0.02458525262773037
            ],
            [
                -0.005882907193154097,
                0.9999821186065674,
                0.0010661549167707562
            ],
            [
                -0.02457856945693493,
                -0.0012104471679776907,
                0.9996971487998962
            ]
        ],
        "rectifiedRotationRight": [
            [
                0.9995121955871582,
                0.010318374261260033,
                0.029476208612322807
            ],
            [
                -0.010284807533025742,
                0.9999462962150574,
                -0.0012901463778689504
            ],
            [
                -0.029487937688827515,
                0.000986359897069633,
                0.9995646476745605
            ]
        ],
        "rightCameraSocket": 2
    },
    "version": 7
}

                      JamesYeh Thank you, the second one is the right one. The first one is the initial config needed to start calibration, the second one is the full config generated by the calibration.
                      We are working on that. I will get back to you as soon as we resolve it.

                        What do you mean by branch? USB 3.2 or Thunderbolt 4 port? We tried both. We also tried with and without your Y adapter.

                          JamesYeh open terminal, navigate to depthai folder and type git branch, you should see similar output to the one on the picture. The row with * is the branch name we are looking for

                            This is what I saw... Lite_calibration.

                            @"JamesYeh" I would like you to try one little experiment.
                            in your depthai/ folder, locate the calibrate.py file. open it with any text editor or an IDE like Pycharm.
                            On lines 611-614
                            you can locate this code:

                            if self.args.factoryCalibration:
    self.device.flashFactoryCalibration(calibration_handler)
is_write_succesful = self.device.flashCalibration(calibration_handler)

                            change it to

                            if self.args.factoryCalibration:
    self.device.flashFactoryCalibration(calibration_handler)
is_write_succesful = self.device.flashCalibration2(calibration_handler)

                            The change is int the self.device.flashCalibration2

                            It can happen that this code piece is not on above mentioned lines, it depends on the depthai branch. Either way yor calibrate.py file should contain those lines so you can find them.

                            When it is done, run the calibration again, the same way as before. Now, it should end with en Error printed out in the terminal. Send us the error please.