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Peer-Review Record

Adjusting the Regular Network of Squares Resolution to the Digital Terrain Model Surface Shape

ISPRS Int. J. Geo-Inf. 2020, 9(12), 761; https://doi.org/10.3390/ijgi9120761

by Dariusz Gościewski^1,*

and Małgorzata Gerus-Gościewska²

Reviewer 1: Anonymous

Reviewer 2: Anonymous

Reviewer 3: Anonymous

ISPRS Int. J. Geo-Inf. 2020, 9(12), 761; https://doi.org/10.3390/ijgi9120761

Submission received: 28 November 2020 / Revised: 15 December 2020 / Accepted: 17 December 2020 / Published: 20 December 2020

Round 1

Reviewer 1 Report

All necessary corrections were introduced.

Author Response

Response to Reviewer 1

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Q1)
All necessary corrections were introduced.

A1)
The authors of the article wish to thank you for the review received.
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Best regards,
Authors

Author Response File: Author Response.pdf

Reviewer 2 Report

My comments were not taken into account.

There are no changes in the text, only additions: the explicit mathematical formulation of the concepts used, a more detailed description of the experimental data, and explanations intended to justify the choices made, with which I already did not fully agree as stated in my previous comments.

Author Response

Response to Reviewer 2

The authors of the article wish to thank you for the review provided and the comments it contains, which have allowed the quality of the paper to be enhanced.

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Q1)
My comments were not taken into account.

A1)
The authors of the publication made every effort to correct the original version of the article in accordance with the comments of the reviewer:

The content of the article has been supplemented based on the Reviewer’s comments.
All Figures have been corrected in line with the Reviewer’s suggestions.
A missing formulas has been added.
The terms used in the article are explained.
Key methodology elements have been added.
The article has been supplemented to include additional literature items.
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Best regards,
Authors

Author Response File: Author Response.pdf

Reviewer 3 Report

The manuscript titled "Adjusting the regular network of squares resolution to the digital terrain model surface shape", Authors Dariusz Gościewski and Małgorzata Gerus-Gościewska describe a procedure for optimizing the grid size (i.e. the density of the points) of the Digital Terrain Models based on the different morphological complexities of the terrain.

In this second version, the manuscript was improved following the suggested revisions. The new version has clarified many aspects of the work and, in my opinion, deserves publication after a minor revision.

Some revisions:

Page 2, line 88: the new sentences added by the Authors at the end of the introduction contain many conclusions: better separate the sentences of the Introduction from the sentences of the Conclusions, and move the latter to the Conclusions section

Page 3, lines 108 and 109 are repetitions of 101-103

Page 6, lines 230-231 are repetitions of the lines just above

Page 15: could be useful for readers the morphological index value applied to a real case (the numerical value)

English improvements are needed

Author Response

Response to Reviewer 3

The authors of the article wish to thank you for the review provided and the comments it contains, which have allowed the quality of the paper to be enhanced.

--------
In this second version, the manuscript was improved following the suggested revisions. The new version has clarified many aspects of the work and, in my opinion, deserves publication after a minor revision.

Q1)
Page 2, line 88: the new sentences added by the Authors at the end of the introduction contain many conclusions: better separate the sentences of the Introduction from the sentences of the Conclusions, and move the latter to the Conclusions section.

A1)
The article has been corrected in line with the Reviewer’s suggestions.

--------
Q2)
Page 3, lines 108 and 109 are repetitions of 101-103.
Page 6, lines 230-231 are repetitions of the lines just above.

A2)
The content of the article has been corrected based on the Reviewer’s comments.

--------
Q3)
Page 15: could be useful for readers the morphological index value applied to a real case (the numerical value).

A3)
The value of the RMS coefficient has been added to Figure 12. It allows to evaluate the change in accuracy of the real model. The scale of the morphological index has been normalized. This scale is shown under Figure 12.

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Q4)
English improvements are needed.

A4)
The English language was verified.

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Best regards,
Authors

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.

Round 1

Reviewer 1 Report

The reviewed article entitled "Adjusting the regular network of squares resolution to the digital terrain model surface" focuses on the problem of increasing the accuracy of terrain grid net determination. Unfortunately, the research is not technically sound. The methodology is nearly not presented, despite one commonly known formula for root-mean-square. It is necessary to present the algorithm of calculations with formulas. The literature review is poor. The authors do not refer to other studies and other known methods in the discussion. This is a serious lack of content in the publication. The way of writing the article is hard to follow, e.g. the introduction contains several threads in one paragraph that is too long. Throughout the work, authors should use separate paragraphs for subsequent threads more often to increase the readability of the text. The authors do not present the method of estimating the accuracy of the results concerning the adopted methodology and other previously developed interpolation methods. The quality of the presentation is generally good, however, the figures need corrections. The text has not been thoroughly checked before submission, for example in row 128 there is an editorial draft note. The English level is appropriate. The paper would be interesting to the journal readers as it covers an interesting topic, however, the overall merit is negative. The reviewer suggests a rejection of the manuscript from publication.

Remarks to the authors:

"The correct execution of this task is largely determined by a system operator’s intuition and experience." - does the analysis of local height changes not apply?
fig.2 - poor quality of legend captions, lack of unit
fig.3 - no parameter name and no unit, no RMS unit. S and RMS values are hardly readable in this case. Perhaps it is worth moving them out of the graphics.
"diverse" is repeated over and over again (not very diverse, more morphologically diverse, most diverse) - I propose to define the scope of the analysis and name them, e.g. Section 1, 2, 3.
The variable "n" (row 169) should be written in italics and should refer to formulas (which are missing in the publication).
Fig. 5 - no units, pink is not in the chart, no explanation of a darker shade of green. The same applies to Fig. 7 and Fig. 8
Rows 106-197 - the authors talk about a certain modification procedure but do not provide any formulas.
Row 200 - "The index was correctly determined" - the authors do not provide an evaluation criterion
220-223 "the method (...) is universal for all the examined cases" - again - this is not supported by a thorough analysis.

Reviewer 2 Report

The creation of a regular grid based on a point cloud requires the search for a trade off between the volume of data and the accuracy of the product obtained by interpolation. This is a classic problem that has been dealt with for a long time.

This article does not really bring new ideas. It is not clearly positioned between an analytical approach (which should be based on the theoretical analysis of the spatial frequency spectrum, or any equivalent formalism) and an empirical approach (which would benefit from relying on a real DTM to consider true "diversity"). The scope is not clear. For instance, the authors refer several times to lidar as the typical example of data to be resampled, but the only pratical case is based on bathymetry.

I do not understand the relevance of dividing the area into rectangular sub-areas, nor of classifying the index into discontinuous intervals. In both cases, we are dealing with continuous characteristics.

More seriously, the morphological index is not appropriate for describing landforms and their impact on error. This is because it does not take into account the spatial autocorrelation of the error. For example, it seems that the surface models shown, for instance, on fig. 7a, 7b, 7c, have the same drainage density and only differ in terms of height amplitude, so that they would require the same resampling density. This already appears in the introduction, where it is written that zones with "small height differences" (line 54) do not require a high resampling density. The optimal density should not consider the height amplitude and not even the slope, but rather the curvature.

The authors do not explain how the pp cloud was generated (line 88). Do they really have a random distribution ? More important, if the mathematical surface (fig. 1) is considered as the true terrain, the pseudo-measuring points should be generated with a realistic error, the contribution of which cannot be ignored.

Some important terms are misused:
- "resolution" (used even in the title) is inappropriate (I think the authors mean mesh size, while resolution is the ability to separate two close topographic objects and is not considered in this article);
- "diverse" is inappropriate to describe areas with rapid slope variations, which can be very homogeneous landscapes.

Reviewer 3 Report

A very interesting approach to an old problem. The presentation is clear and well presented. I would like, however, to have seen some practical results and not only simulations

Reviewer 4 Report

Although the topic is not new, there are ideas that may deserve publication after a major revision.

In my opinion, the main problems are:

- Authors generate a virtual survey on the basis of a mathematical (trigonometric) function which cannot be representative of the real terrain morphology: only in the last part of the discussions they apply the procedure to a real "multi-beam echo sounder" available survey (for which a lot of information are missing, see below). In my opinion, the study should start from a real survey, taking into account a real terrain morphology;

- Authors should provide more information about the subdivision of the areas, especially on the positioning of the edges, because some choices are incomprehensible (Figure 8a: areas with similar morphology belong to both the Z1 and Z2 zones, or Z2 and Z3 ... this apparent contrast requires more explanations).

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Adjusting the Regular Network of Squares Resolution to the Digital Terrain Model Surface Shape

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