Review Reports - Irregular Area Cartograms for Local-Level Presentation of Selected SDGs Indicators Based on Earth Observation Data

Round 1

Reviewer 1 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

Thank you for the authors’ efforts in revising the manuscript. The current version shows some improvements compared to the previous submission. However, the following issues still need to be addressed:

While the authors have provided a detailed summary of various SDG indicator visualization methods, there is a lack of discussion on cartogram-related research. Given that the paper focuses on cartograms, it is recommended to include a review of recent developments in cartogram research.
For figures containing multiple panels—such as Figures 4, 5, 6, and 7—please label each subfigure with a letter or number and provide corresponding descriptions in the caption.
In the choropleth map legends, the boundaries between adjacent classes are unclear. For example, in the first panel of Figure 6, it is ambiguous whether the value 100 belongs to the second or third class. Similar issues are present in Figures 7, 8, 9 and 10.
The term "The mean cartogram error" appears multiple times in the text but is not clearly defined or explained.
In Section 3.4, although Figure 5 provides some insight into the questionnaire, it would be helpful to include more details regarding the survey design—such as the number of maps used, classification of user tasks, and procedure. In Section 4.3, for the analysis of results, it is recommended to incorporate statistical methods suitable for non-independent samples rather than relying solely on simple frequency comparisons.
The content in Chapter 5 (Discussion and Conclusion) could be streamlined. Some parts may be better suited for integration into Chapter 2 (Related Work).

Comments for author File: Comments.pdf

Author Response

Thank you for your comments. Detailed responses have been provided in the file. Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

In this paper, the authors present a case study and preliminary user study for using cartograms to visualize selected statistical data in the context of SDGs.

The paper is very well written, in good English (as far as I can judge as a non-native speaker), and well structured. However, I have to say, I didn't really get a clear picture of what the authors want to say or what the key contribution of the paper is. The authors try many things at the same time: giving a quite detailed discussion of the particular SDG indicators and their derivation from EO data; Reviewing the body of publications in which SDG data is visualized and delivering a detailed cartographic critique of the visualizations and maps therein; Proposing cartogram-based visualization of SDG data for Poland and doing a qualitative assessment of the visualization; Doing a user study including qualitative and quantitative assessment criteria. This is an interesting compilation of information, but as it stands, none of the aspects is covered in enough depth to justify a journal publication on its own, and I am not convinced the compilation of multiple of those aspects into one paper results in a contribution that readers will be able to extract much insight from, or even pinpoint what the exact contribution is.

So I am voting "reject" not for lack of formal quality, but for lack of focus and cohesion, and would instead suggest to the authors to split up the publication into two papers: one reviewing the state of the art & practice in SDG visualization, in which maybe a broader view on the totality of SDGs could be initially attempted, with a more detailed review of the targets and indicators selected for this publication. This would give the authors the space to elaborate even more on the discussion and analysis of the practice of visualization in these publications, maybe improve/formalize a bit the process of sampling relevant publications (again, with a potentially broader view on SDGs in general), and visualize the results or otherwise attempt a more formal presentation or synthesis. I think this would make an interesting paper for a cartographic journal outlet. A second paper could then present a full usability study on the proposed visualization of SDG data as cartograms - but I am afraid the study would have to be re-designed and re-done, or at least significantly expanded upon, in order to derive insights on cartogram legibility that go beyond the particular case study and a very limited / biased user population, and contribute to our general solidified understanding of this visualization technique.

So I am putting my vote towards sending the draft back to the authors for serious reworking and re-submitting, probably under a different title, because I judge the current draft a little too "all-over-the-place" and the scientific depth of each individual part not quite sufficient for journal publication. However, if I am outvoted I am also fine with an accept decision, as I think this is a somewhat solid paper, even if I judge the depth insufficient.

In the latter case, here are some suggestions for minor improvements:

- In the abstract, SDG 11 and 13 should be mentioned by name, and the numeric references for targets and indicators should be omitted, as readers will not generally readily know what these refer to.

- Line 49: Superfluous "(SDGs)"

- Figure 1 doesn't add a lot of information and could be omitted

- The explanation of the "Air pollution" and "Green areas" SDGs in the introduction is very elaborate and could be shortened

- Line 170 "In total," instead of "Finally,"

- Line 237 "It should be emphasized that in the case of analyzed maps of 11.6.2, 11.7.1 13.2.2" - it is very confusing to remember what these numeric indicators refer to (also applied to many other places in the draft where these are used) - so you could consider giving somewhat more meaningful abbreviations instead, e.g. "particles", "greenArea" etc.?

- Lines 270-282 - again, this is very verbose and could be shortened

- L 352 "particularly in R" omit

- L 390 the link to the (inactive) form is irrelevant, better include a screenshot(s) in the paper or the appendix

- A figure giving an overview of the stimuli used in the user study would be helpful. As it stands, the draft only provides an exemplary screenshot. Figures 6 and 7 would maybe be sufficient, but should come earlier in the paper.

Author Response

Thank you for your comments. Detailed responses have been provided in the file. Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report (New Reviewer)

Comments and Suggestions for Authors

Using irregular area cartograms is an interesting topic, it's advantages as well as the steps of production are well explained in this paper.
I would argue, however, about how much it can be understood by average people (not highly educated and/or experienced with complex cartographic representations). The conducted survey ha too few respondants and their educational level is not represent normal population. I'd suggests some elaboration on these limitations of the usability of area cartograms.

Minor comments/questions:

3.2.1:
- The abbrevation GIOS is not explained at all.
- Why was the data 2 times resampled (first while converting from NetCDF to GeoTIFF, then after calculating monthly averages)?

Figure 9: Why are forests excluded from green areas? Those are the healthiest green areas, without them it seems like rural areas has less green areas than cities.

4.3: The low number of respondants and the high rate highly educated persons and skilled map readers does not represent well the population.

Author Response

Thank you for your comments. Detailed responses have been provided in the file. Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 4 Report (New Reviewer)

Comments and Suggestions for Authors

The article provides relevant research in the field of geoinformatics and cartography, but minor improvements in clarity and methodological precision would be advisable. The presented topic is current.

It is necessary to quantify the criteria for evaluation or comparison — for example, explain how the accuracy, usability, or quality of the visualization was evaluated. If a subjective evaluation was applied (eg visual interpretation), it is necessary to add information about the size of the sample, the profile of the respondents, etc.

In some figures (e.g. 8-10) the legends are too small or blurred. It would be useful to highlight what is most important for the reader to notice in each figure.

In Chapter 5. Discussion and Conclusion, it would be useful to compare your findings with previous research to demonstrate the contribution of the study. The conclusion should specifically emphasize the main findings and practical application and indicate future research directions.

Author Response

Thank you for your comments. Detailed responses have been provided in the file. Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report (Previous Reviewer 2)

Comments and Suggestions for Authors

After multiple rounds of revisions, the concerns I raised have largely been addressed. Regarding Figures 7, 8, and 10, since area cartograms are inherently distorted in terms of distance, the scale bars placed on these maps are no longer meaningful. I recommend removing the scale bars from all area cartogram figures. Once this change is made, the manuscript will be suitable for acceptance.

Author Response

Dear Reviewer,

We like to express our gratitude for your insightful review of our manuscript. Below, we respond to your comments. Your comments are in black, while ours are in blue.

Comments on the figures were added, figures 7, 8 and 10 were changed. New figures were added to the text and uploaded to the system.

Reviewer 2 Report (New Reviewer)

Comments and Suggestions for Authors

OK, formally the article is now in good shape.

In the end it is down to the editor to decide whether this article is suitable for the journal.

Author Response

Dear Reviewer,

We like to express our gratitude for your insightful review of our manuscript.

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

Comments and Suggestions for Authors

The article "Applying Area Cartograms to Visualize Sustainable Development Goals Indicators Based on Earth Observation Data" is an interesting paper that merely outlines the potential applications of various area cartogram types for the visualization of the components of sustainable development indicators.
The study analyzed some indicators related to SDG11 (Goal 11 – Sustainable cities & communities), and SDG13 (Goal 13 – Climate action) such as:
• Target 11.6: Reduce the environmental impacts of cities (Indicator 11.6.2 – Annual mean levels of fine particulate matter);
• Target 11.7: Provide access to safe and inclusive green and public spaces (Indicator 11.7.1 – Average share of the built-up area of cities that is open space for public use for all);
• Target 13.2: Integrate climate change measures into national policies, strategies, and planning (Indicator 13.2.2 – Total greenhouse gas emissions per year).

Certain significant changes are required in the article before publication.

General comment
One of the most significant omissions in the work is that the authors did not examine the built-up area of cities that are related to the specified indicators; instead, they examined the indicators for the entire country by administrative division of Poland. In this instance, analysis is required. By focusing solely on the topic of using area cartograms to visualize air pollution and green spaces based on Earth observation data (e.g., Copernicus Atmosphere Monitoring Service), the authors might devote less emphasis to explaining the Sustainable Development Goals of the analysis. It could have been simpler to say that 3 of the 250 possible indicators found on the website of the Statistics Poland institution were analyzed.

For all obtained choropleth maps and irregular area cartograms that represent the results of the research, as well as the map of the administrative division of Poland, it is necessary to provide geographic coordinates (possibly data on the scale of the display, the direction of north, etc.)

Remove highlighted text from Figures 3, 4, and 7.

Specific comment

Lines 13-14: Instead of the targets listed in the abstract, give the numbers of specific indicators analyzed in the article (for example 11.6.2)

Lines 20-22: What evidence supports the assertion that the analysis demonstrated that area cartograms are a useful tool for showing geographical differences in factors like the availability of urban green space and air pollution at the county and municipal levels? Has an analysis been done on the effectiveness? Which settings made this appear? What other displays are in comparison?

Line 57- 110: This article lacks new approaches in displaying Area Cartograms, a new methodology. It uses only already known approaches in displaying specific phenomena using area cartograms.

Table 2: Are these all possible GIS software used for the generation of contiguous area cartograms?

Author Response

We appreciate the reviewer's constructive feedback and thoughtful suggestions, which we believe help to improve the quality and clarity of our manuscript. The English language has been checked and corrected by a professional. The corrected parts of the text are highlighted in red. Deleted or relocated text fragments are marked in red with strikethrough. Below (word file) we respond to each comment in detail and outline the revisions.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

While the topic of this paper is potentially interesting, I regret to inform the authors that the methodological approach is overly simplistic. The study primarily conducts a superficial comparison between area cartograms and choropleth maps without substantial innovation. The key findings essentially reiterate previously established knowledge, with the only novelty being the application of area cartograms to a new domain. Below are my specific concerns:

The background section provides a thorough overview of visualization methods for SDG indicators but fails to adequately address the existing research on area cartograms. A more balanced review of prior work is needed.
The statement in Line 180 regarding "monitoring changes in SDG indicators" is not substantiated in the subsequent maps or analysis. Either the claim should be supported with evidence or revised for accuracy.
All map-based figures should include a north arrow for proper orientation. This is a basic cartographic convention that should not be overlooked.
The "maximum mean error" mentioned in Line 310 is ambiguous and requires precise definition. The authors should explicitly specify whether this metric pertains to distance error, area distortion, positional displacement, or another form of error.
The left panel in Figure 9 is incorrectly labeled as a choropleth map. This discrepancy should be corrected to maintain accuracy in representation.
Gastner-Newman cartograms do not represent all area cartograms, and research conclusions regarding Gastner-Newman cartograms may not apply to other types of area cartograms.
The comparison between area Cartograms and choropleth maps relies solely on visual assessment without quantitative or statistically validated measures. This undermines the scientific validity of the conclusions.

Given these significant shortcomings, I recommend rejection in the current form. The study would require substantial revisions—particularly in methodological depth, analytical rigor, and clarity of presentation—to meet the standards of a scholarly publication.

Author Response

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

This study evaluates the use of area cartograms for visualizing Sustainable Development Goal (SDG) indicators related to air pollution (11.6, 13.2) and urban green spaces (11.7) in Poland, at municipal and county levels. Results highlightings the method's potential and limitations for fine-scale SDG monitoring.

However, this manuscript in current version doesn't meet the publication standard.

problems:
1. The study mentions using Sentinel-2 (10 m) data for mapping green areas and assessing their condition, but it lacks essential details like acquisition dates, product levels, atmospheric correction methods, cloud masking, exact band selection, NDVI/HR-VPP calculation parameters, quality control, and validation steps.

2. The paper states that 120 publications were analyzed but does not describe the selection process. What are databases, keywords, time range, inclusion/exclusion criteria, or representativeness checks?

3. Effectiveness of the cartogram vs. choropleth maps is assessed only qualitatively through descriptive observation. No quantitative evaluation (user testing, statistical analysis, accuracy metrics) is provided. No information concerning the evaluation participants. No objective visual performance test.

4. The paper notes that cartograms are rarely used in SDG mapping and cites a few related works, but does not perform a systematic or empirical comparison with other cartogram implementations in similar or different domains. Other domains are cited, but only in passing.
What are the conclusions of other cartogram visualization research?
Lessons from these domains are not deeply analyzed or applied to strengthen the argument for cartograms in SDG monitoring.

5. The study aggregates datasets with vastly different resolutions (Sentinel-2 at 10 m, CAMS at ~80 km, demographic/vehicle statistics) without discussing scale mismatch effects. Also, how they handle these raster data with vector boundaries?

6. For this work, relying solely on subjective visual inspection is not sufficient for strong academic conclusions. Omitting other cartogram-related research empede the reader understand the novalty of this research.

7. some typos, for example: Line 71, line 130. Writing and organization are not fluent.

Author Response

Author Response File: Author Response.pdf

Reviewer 4 Report

Comments and Suggestions for Authors

The manuscript integrates Earth Observation (EO) data with statistical sources to apply area cartograms visualizing urban green space and air pollution indicators under Sustainable Development Goals. It reveals spatial disparities at municipal/county levels in Poland. This study addresses a gap in fine-scale SDG indicator visualization and provides a scalable methodological framework for dynamic SDG monitoring. However, several aspects need improvement before the manuscript can be considered for publication.

In the introduction section (Section 1), air pollutants are mentioned when introducing SDGs monitoring. It is suggested that the definition of pollutants in Section 3.2 be moved to the introduction section.
In Section 3.4.3, it is necessary to supplement the explanation of the basis for selecting the algorithm parameters of "municipal-level units iterating 2 times and county-level units iterating 5 times".
Section 4.1 mentions the limitations of the application of area distortion maps. It is suggested to try to put forward corresponding mitigation solutions.
It is recommended to check the typesetting of the whole paper to avoid duplicate chapter numbers. For example, the Results section and the Discussion and Conclusion section have duplicate numbers, both marked as "4.".
Attention should be paid to the consistency of professional terms in the context. For instance, "SDGs" in the abstract is inconsistent with "SGDs" in the keywords, and "powiat" and "county" are mixed. It is suggested to proofread the whole paper and simplify long sentences to ensure the standardization of terms in the manuscript.
In Table 1 (Section 3.4.1), the units of PM2.5, PM10, and NO₂ are all "μg/m³", while in Figures 5-7 (Section 4.1), the unit in the legend is marked as "μg/m2". To avoid ambiguity, it is suggested to correct the unit or add a text description.

Author Response

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

The authors carefully revised the original article based on the reviewers' comments, which significantly improved the quality of the paper. This paper has certain reference value for peers and is of great importance in the application of area cartograms to visualize sustainable development goals indicators. My suggestion is to publish the paper in this form.

Reviewer 2 Report

Comments and Suggestions for Authors

While the authors have made efforts to address previous feedback, several critical issues remain unaddressed and necessitate further revision:

The literature review remains descriptive rather than analytical. Existing related studies are merely categorized and quantified by number, without substantive discussion of their research content, methodologies, or gaps in the current body of work. A deeper synthesis is essential to contextualize the contribution of this study.
The term "a maximum mean error" (Line 405) remains ambiguous. It is unclear whether this refers to area error, positional error, or another form of metric. Moreover, the relationship between this measure and the subsequently introduced Borderline Accuracy Index (BAI) requires explicit explanation to ensure methodological clarity.
In Chapter 4, the map legend contains multiple color blocks that do not correspond to any features on the actual maps. This discrepancy undermines the readability and interpretability of the figures. It is recommended that all non-represented elements be removed from the legend to avoid confusion.
Although a quantitative evaluation using the BAI has been added, the sample size remains insufficient to support meaningful statistical conclusions. The limited data significantly weaken the validity of the findings. Expanding the sample size or strengthening the methodological justification is critical to establishing robustness.

Given the extent of revisions still required and the failure to adequately address these critical concerns, I recommend rejection.

Reviewer 3 Report

Comments and Suggestions for Authors

The author solved all my questions. However, I still expected a quantitative test with the design.

Reviewer 4 Report

Comments and Suggestions for Authors

The authors have provided a satisfactory response to the comments. Therefore, the manuscript may be considered for possible publication.