Natural Cities Generated from All Building Locations in America

Round 1

Reviewer 1 Report

Structure of document is poor and this form not adequate for publishing. Must be improved. The research methods and resoult not adequately presented, commented and described.

Author Response

Thank you very much for your review.  Please find it in the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript by Jiang entitled “Natural Cities Extracted from All Buildings in America” presents a data set of “natural cities” in the lower 48 states of the US. The data set fits MDPI Data’s aims and scope and has the potential to be of interest to its readership. However, in addition to English language editing and improvement, both the data set and manuscript need a thorough revision before consideration for publication. 

(i) The main criticism regards the quantification of the results accuracy. For example, how does the resolution and/or accuracy of the original data set from which the centroid of the buildings were retrieved affect the results? How do the results coincide with previously published land cover maps?

(ii) In addition, interesting how the author states how city limits are often imposed “top-bottom” inviting to overcome this approach, but presents the results using administrative borders (country level) rather than natural limits. Perhaps expand to a physical entity (e.g. North America) to include trans-boundary cities, such as for example El Paso, Texas (USA) and Ciudad Juarez, Chihuahua (Mexico). If building footprint data are only available for the US, then make the case for the need of this information.

More punctual comments follow.

L29. Please quantify “huge”.

L33-34. Reference needed.

L38-L44. Function misplaced.

L49. 120 or 125 million?

L67. It would be more informative to label the sub-panels with the correspondent reference city cited in the caption, possibly adding its administrative boundary, in addition to link them to the correspondent geographic location in the main panel.

L68-72. Please reword the caption based on edits suggested in comment L67. I would also recommend to consider adding a table summarizing some informative statistics for each city (area, perimeter, fragmentation coefficient, etc).

L78-79. How well? Please quantify.

L81. Potentially, but how so? Please expand.

L84-85. Agreed, but would it be possible to quantify this?

L87. Do not cite unpublished works unless accepted for publication, which is not the case for Ren et al. (2019).

L87-88. Rather than inviting to contact the author, I would encourage to deposit the data set in an online repository and release it to the public. In fact, the MDPI Data “Aims & Scope” section states: “Described datasets need to be publicly deposited prior to publication, preferably under an open license, thus allowing others to re-use the dataset”.

Author Response

Thank you very much for your review.  Please find it in the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

The author has presented an interesting and exciting research topic. However, there are a few questions that need to be addressed. 

1. Why the head/tail breaks method is suitable for defining natural cities. 

2. The author has proposed a head/tail break method that is based on individual triangles. Why is the suggested method much better than the previous studies? 

3. The paper lacks the results and discussion sections. 

Author Response

Thank you very much for your review.  Please find it in the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

This version of paper is significant improved, suggest to accept 

Author Response

Thanks!

Reviewer 2 Report

In the current version of the manuscript, the author addressed the vast majority of my previous comments. However, in my opinion a few minor points remain to be addressed before consideration for publication in MDPI's Data. In particular:

L8-9. Please reword as follows: "Authorities define cities – or human settlements in general –  imposing top-down rules in terms of whether buildings belong to a city.

L10. "[...] to a city [...]".

L13. "[...] all building footprints of America (mainland) and their centroids more precisely [...]".

L24-27. Valuable addition, but please avoid citing Wikipedia in a scientific paper.

L30-31. "All" depends on the definition of natural cities and the methodology used for their extraction. Please delete.

L32. If possible rename the page name to include the term "natural" instead of just "uscities".

L42. Over one million as in >10^6?

L54. Good, my previous comment was probably due to poor formatting of the first draft. Perhaps reword as "The following function was used:".

L79. "Differently [...]". Also, please provide examples of "previous studies on natural studies".

L86. "[...] defined [...]".

L93. "[...] but not always so for scientific purposes." 

L93-94. I don't find this sentence to be necessary.

L96. I still believe that overlying the polygon defining the limit of each selected city (UA) and the derived discussion would be extremely informative here. Please also add a scale for each selected city or alternatively homogenize to the same scale.

L97. "Selected natural cities [...]".

L99-100. Link already provided twice in the manuscript. 

L101-102. Please reference additional material rather than using a verbose and unnecessary sentence in the caption.

L110-113. Great, though in my opinion too simplistic. For example, "some very complicated way"? Please define more precisely.

L113-116. Reference needed.

L117-121. Unclear and possibly out of focus. What does the author mean here?

L123-136. Very good.

L140-141. "This paper describes a dataset of 2.1 million natural cities in the US automatically generated from 125 million building footprints." 

L145. Perhaps "urban studies" instead of repeating "cities"?

L147. Perhaps "[...] following a fractal distribution"?

L150. Perhaps "standard top down approach"? Who/what is the "government"? Replace "actually" with a more informative adverb.

L153. "[...] for future research."

L156-157. The goal of the paper should not be to promote other research... Instead, please acknowledge the reviewers' work.

Author Response

Thank you very much for your review.  Please find it in the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

However, computationally, the new approach is much better, since the number of triangles is far less than that of edges.

- What's the computational efficiency of this work? 

Author Response

Thank you very much for your review.  Please find it in the attachment.

Author Response File: Author Response.pdf