A Method for Measuring the Absolute Position and Attitude Parameters of a Moving Rigid Body Using a Monocular Camera

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The article titled “A Method of Measuring the Absolute Position and Attitude Parameters of a Moving Rigid Body Using a Monocular Camera”, relates to my area of interest that’s why I suggest or recommend some points which may help to improve the readability as well as the overall structure of this manuscript. The following are my suggestions, recommendations, and questions for this article which may help to improve the quality of this manuscript are as follows.

 

1.     Title is good and understandable for readers (no changes suggested).

2.     Abstract

·       Its better to start your abstract with related work and problem statement of your work.

·       Abstarct is too long please be precise.

·       Compare your work with existing ones and highlight your contributions.

3.     Introduction

·       What is /are your research question?

·       It's better to break the introduction section into multiple sections (Seems everything is explained in the introduction)

·       What is the main motivation of this research to elaborate it separately in the introduction section?

·       Add contributions part in detail

·       Paper organization is missing

4.     Theoretical derivation of methods

·       Add some small paragraph at the start of this section (line 72-73)

·       This section must be improved by identifying each sub section.

 

5.     Experiments and data analysis

·       Try to relate this section with section 2

·       Justify table 1 and table 2 contents

6.     Conclusions

·       Minor revision is required in this section according to contributions and comparision

 

7.     General Comments

·       In the introduction, very less citations are there Need to revise it properly.

·       Kindly cite the latest articles to your work

·       Check all the references carefully.

·       Check all figures carefully.

 

Comments on the Quality of English Language

Overall English is better in this article. just need to recheck some minor spell-checking and grammatical errors.

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions highlighted in the re-submitted files.

1 The abstract has added the problems that we need to solve in our actual scientific research work.

2 The first and third parts of the introduction are the content I added regarding research issues in the paper, as well as relevant literature content.

3 In the experiment and analysis, we have added the description of relevant parameters for high-speed cameras and lighting fixtures.

4 Section 3.3.2 added a comparative experiment with binocular attitude measurement.

5 In section 3.3, we added an explanation of the distance between the turntable and the camera at 2.21m.

6 All literature provides a link in the sources used.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The solution in the article requires the installation of control points on the rigid body when measuring the position, which cannot be achieved in non-contact measurement. The direct linear transform (DLT) method assumes that the camera model is an ideal linear model, but in fact, due to factors such as tangential distortion, radial distortion and lighting conditions, the camera imaging process is nonlinear. Therefore, the DLT method cannot fully and accurately describe the camera imaging process, this can lead to errors in the measurement results. The reason for using DLT is to avoid inaccurate calibration due to the small calibration board when calibrating in large space. But when measuring the entire machine, a zoom camera can effectively solve the problem. When the camera is in the initial large field of view, it is mainly used for coarse positioning and controlling sensor rotation, inaccurate internal parameters at this time will not affect the final measurement results. When the camera captures more detailed local images by increasing the focal length, the field of view becomes smaller and accurate calibration can be achieved without the need for a huge calibration board. The small errors that may exist when the camera zooms can be solved through online calibration. Because there is no need to install control points anymore, non-contact measurement is also achieved. The binocular positioning system can also estimate the depth of an object, and during measurement, the object can not only rotate, this leads to a significant increase in the practicality of the solution. The solution in the paper is difficult to directly transfer to actual use scenarios. The rigid body only undergoes rotation without translation, and when calculating the angle, the camera needs to simultaneously capture the control points on the rigid body and the control points in world coordinates. This leads to limitations on scenario availability for solution implementations. Although the paper uses a zoom camera, it does not fully utilize the power of the zoom camera. The method of not requiring camera calibration alleviates the error caused by zoom, but the advantages of using a zoom camera are not reflected in the scheme.

Comments on the Quality of English Language

There are some typos and grammar problems in the text.

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions highlighted in the re-submitted files.

1、I would like to discuss non-contact measurement with you. Although control points are installed on the rigid body during the measurement, the entire measurement process still belongs to non-contact measurement, which is based on cooperative goals;

2、The processing speed of DLT method is relatively fast. Although the error is relatively large, the accuracy can be improved to a certain extent through the 3-5 step Gaussian Newton iteration method, the rotation matrix between the body coordinate system and the world coordinate system. The specific error can be seen in the experimental data in the paper;

3、I agree with what you said that a zoom camera can solve the problem of inaccurate calibration due to the small calibration plate in large space calibration. Because the zoom camera has this function，the most applications require a zoom camera. However, measuring once requires focusing once, and calibrating once after focusing is very cumbersome. This method used in this article can achieve pose measurement without the need for complex calibration processes when the focal length of each measurement changes. So the measurement method has certain practical application significance;

4、The measurement method in this article is mainly applied to the validation of the dynamic model of the paddy field laser grader. Please take a look at my newly submitted paper for details. Model validation requires repeated measurements, and each measurement requires focusing to ensure clear shooting. Therefore, this measurement method is very suitable for this application situation;

5 Here are some modifications made in my resubmitted paper. Please review them.

1) The abstract has added the problems that we need to solve in our actual scientific research work.

2) The first and third parts of the introduction are the content I added regarding research issues in the paper, as well as relevant literature content.

3) In the experiment and analysis, we have added the description of relevant parameters for high-speed cameras and lighting fixtures.

4) Section 3.3.2 added a comparative experiment with binocular attitude measurement.

5) In section 3.3, we added an explanation of the distance between the turntable and the camera at 2.21m.

6) All literature provides a link in the sources used.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The article on the topic "A Method of Measuring the Absolute Position and Attitude Parameters of a Moving Rigid Body Using a Monocular Camera" presents an interesting and relevant topic of measuring the absolute position and orientation parameters of a moving body using a monocular camera. The authors describe a method that made it possible to obtain highly accurate data on the position and orientation of a rigid body using only one camera. The current manuscript is interesting and novel, so due to that the manuscript could of valuable contribution to the scientific community. The undertaken issue is interesting and worth of disseminating. In general, I would like to note the high quality of the work done, but also pay attention to some comments:

 

Point 1: In the introduction chapter, it is worth displaying the percentage of the use of monocular systems compared to binocular and multi-eye systems.

Point 2: Despite the detailed description of the method, the article does not cover the necessary camera parameters, such as focal length or angle of view. Their specifications are required.

Point 3: In Figure 3, it is desirable to display the overall parameters of the turntable for a better understanding of its size.

Point 4: Line 196-199, It is necessary to provide justification for the distance from the turntable body to the chamber of 2.21 m. Why exactly 2.21 m?

Point 5: The authors do not mention the possible limitations of the method. For example, what is the minimum size of an object that can be measured using this method, and what is the measurement accuracy for objects of different sizes?

Point 6: The article does not present the results of testing and comparison with other existing methods. Such information would be useful in confirming the effectiveness of the proposed approach..

Point 7: It is necessary to provide DOI or a link in the sources used.

Point 8: It is necessary to specify the operating conditions of the monocular camera. For example, if the experiment was conducted using a lamp, what is the luminous intensity of the lamp? If in natural conditions, then in the light of day or in the evening? And have these conditions been compared?

Author Response

Thank you very much for taking the time to review this manuscript. Please find the detailed responses below and the corresponding revisions highlighted in the re-submitted files.

1 The abstract has added the problems that we need to solve in our actual scientific research work.

2 The first and third parts of the introduction are the content I added regarding research issues in the paper, as well as relevant literature content.

3 In the experiment and analysis, we have added the description of relevant parameters for high-speed cameras and lighting fixtures.

4 Section 3.3.2 added a comparative experiment with binocular attitude measurement.

5 In section 3.3, we added an explanation of the distance between the turntable and the camera at 2.21m.

6 All literature provides a link in the sources used.

Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have revised their manuscript in accordance with my suggestion. I now recommend it be accepted for publication.

Comments on the Quality of English Language

There are some minor grammar problems. Proof reading thoroughly is required if possible.

Author Response

Please see the attachment.

Author Response File: Author Response.docx