Automated Photogrammetric Tool for Landslide Recognition and Volume Calculation Using Time-Lapse Imagery

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The primary objective of this article is to develop an automated photogrammetric tool for landslide recognition and volume calculation using time-lapse imagery. The innovation lies in the application of a novel photogrammetric algorithm that leverages the SSIM and disparity map computation to rapidly detect collapse events and calculate the associated volumes. The approach is presented in a clear and methodical manner. However, there are several areas where further refinement could be beneficial. The following comments and suggestions are provided:

 

1.       The primary technical methods involved in this paper are Image similarity measurement and point cloud-based 3D modeling. However, the introduction does not adequately discuss these aspects, and the innovative points of the paper are not well refined.

2.       2. The SSIM algorithm is the core of this paper's methodology, yet there is no clear rationale provided as to why SSIM was selected over other image similarity comparison algorithms to demonstrate the superiority of this method.

3.       The paper discusses the impact of vegetation and shadows on landslide identification, but regrettably, it does not further substantiate the reliability of the methods used to remove shadows and vegetation.

4.       Figure 6a shows that different lighting conditions have a significant impact on the SSIM values, making it difficult to believe in the reliability of using the SSIM. ISSIM. I believe the authors should consider developing a method that is more robust under varying lighting conditions, such as using deep learning techniques.

 

5.       The article would benefit from more detailed discussions on the limitations and potential future directions of the proposed method.

Author Response

Thank you for your revision and for your work.

Please see the attached document for our responses. Additionally, in the revised document, the modifications are highlighted in red to make them more visible.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors, I reviewed the paper entitled “Automated Photogrammetric Tool for Landslide Recognition and Volume Calculation Using Time-Lapse Imagery” by Zhipeng Liang et al. This study presents the development and field testing of a novel photogrammetric tool for monitoring landslides through time-lapse imaging. Utilizing fixed multi-view cameras, the tool employs a new algorithm based on structural similarity metrics and disparity maps to detect and quantify collapse events rapidly. The system, tested at the Perarolo landslide site in Italy, demonstrated effective and accurate volume calculations of collapse events over nearly a year.

In equations 2, 3 and 4 there are some constants. Indicate in the text what their value is and how they are determined, since the terms l, c and s will vary depending on these values.

Also indicate how the values of the exponents, alpha, beta and gamma are determined.

Section 2.4.1 should be extended, indicating formulas, equations and matrices detailing the calculations mentioned. This will help to better reproduce the method used.

In Figure 18, indicate the title of the horizontal axis.

Line 143 mentions rates obtained from radar interferometry just before the events. How has radar interferometry been applied? Ground-based radar interferometry, satellite interferometry? This should be explained well. Precisely when there is a landslide, coherence is destroyed and radar interferometry cannot be applied. In fact, in lines 41-42 it is indicated that in relation to radar interferometry, while effective for detecting gradual movements, is inadequate for capturing large sudden displacements.

 

Check the numbering of the figures and the calls to them from the text. In line 280 it should be Figure 10.

Line 271: the phrase “apply a threshold filter with a 0.5m threshold” is redundant.

Lines 338-340. Indicate what these parameters are and how an area of 7 m² is determined from them.

The discussion presents both the strengths and limitations of the developed method. To make the discussion more interesting and complete, it would be beneficial to address the mentioned limitations in greater depth, present potential solutions, and make a detailed comparison with work by other authors in the field. This would not only reinforce the validity of the proposed method, but also place the results in the broader context of current landslide and collapse research. It should be discussed how much the configuration of the cameras affects the different case studies. Is it valid for any case? What is the limiting distance at which the cameras could be placed for the application to be valid in terms of accuracy?

Author Response

Thank you for your revision and for your work.

Please see the attached document for our responses. Additionally, in the revised document, the modifications are highlighted in red to make them more visible.

Author Response File: Author Response.docx

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Agree to publish this article

Reviewer 2 Report

Comments and Suggestions for Authors

Dear authors, I am satisfied with the responses provided and the changes performed to the manuscript. No more changes are required.