Criteria for the optimal selection of remote sensing optical images to map event landslides

Fiorucci, Federica; Giordan, Daniele; Santangelo, Michele; Dutto, Furio; Rossi, Mauro; Guzzetti, Fausto

doi:https://doi.org/10.5194/nhess-18-405-2018

Articles | Volume 18, issue 1

https://doi.org/10.5194/nhess-18-405-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue:

The use of remotely piloted aircraft systems (RPAS) in monitoring...

https://doi.org/10.5194/nhess-18-405-2018

© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 18, issue 1

Research article

|

30 Jan 2018

Research article |

| 30 Jan 2018

Criteria for the optimal selection of remote sensing optical images to map event landslides

Federica Fiorucci, Daniele Giordan, Michele Santangelo, Furio Dutto, Mauro Rossi, and Fausto Guzzetti

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Final revised paper (published on 30 Jan 2018)
Preprint (discussion started on 03 Apr 2017)

Interactive discussion

Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'Comments on nhess-2017-111', Anonymous Referee #1, 15 May 2017
- AC1: 'AC to RC1', Federica Fiorucci, 07 Jul 2017
- AC3: 'Correct version: AC to RC1', Federica Fiorucci, 07 Jul 2017
RC2: 'Comparisions of one landslide mappings from different various remote sensing datasets compared to field work mapping', Anonymous Referee #2, 24 May 2017
- AC2: 'AC to RC2', Federica Fiorucci, 07 Jul 2017
  - AC4: 'Correct version: AC to RC2', Federica Fiorucci, 07 Jul 2017

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

ED: Reconsider after major revisions (further review by Editor and Referees) (17 Jul 2017) by Paolo Tarolli

AR by Federica Fiorucci on behalf of the Authors (25 Jul 2017) Author's response Manuscript

ED: Referee Nomination & Report Request started (27 Jul 2017) by Paolo Tarolli

RR by Anonymous Referee #1 (31 Jul 2017)

RR by Anonymous Referee #3 (21 Nov 2017)

Suggestions for revision or reasons for rejection

The paper is an interesting contribution to the journal. However, it should be pointed out more carefully that it is a showcase of a technical application.

Overall, I only have few major points to highlight and some minor issues as they arose during the reading of the research.
1. The title speaks about criteria for the selection of images. However the criteria are not well defined in the manuscript, and they are only slightly mentioned at the very end of the conclusions. If the point of the manuscript is indeed to present some criteria for selection, these criteria should appear more clearly (e.g. in a list? A well define paragraph?)

2. English needs polishing and revision. Many times the authors overuse ‘i.e.’ or they use sentences in a ‘personal’ approach (“we did this”, “we highlight that”, rather than describing what the research indicates), and many sentences are very long and hard to follow.

3. The work does not compare eight maps. It compares seven maps. The dGPS survey is the benchmark (or ground truth), so it is misleading to include it in the list.

4. One of the main findings of this work is that a photographic landslide signature is best mapped with higher resolution images, while morphometric signatures are better identified with stereoscopic images. However, the reader does not know what photographic signatures VS morphometric ones are (this is never described in the manuscript).

5. The discussion chapter can be shortened and reorganised; much of it is a repetition of the previous chapter, while the reader would expect to find here some additional considerations about the meaning of the results.

Minor comments

Abstract
The abstract needs rewording. It should be more research-oriented, and less of a description of the team effort. E.g. first sentence ‘we executed….’ Could be rephrased to ‘this paper presents…’
The work, furthermore, does not compare eight maps, but rather seven different maps as compared to a reference dGPS survey. The so called ‘8th map’, being the ground-truth, is not part of the considered dataset, but it is the benchmark used to compare all the others.
Lines 19 to 24 report a very long sentence, that needs rephrasing. E.g. “Six maps were obtained through expert knowledge by visual interpretation of images from different sources taken on April 14, 2014. The dataset comprised monoscopic and pseudo-stereoscopic (2.5D) ultra-resolution (0.3 × 0.3 m) images derived using a Canon EOS M photographic camera mounted on a CarbonCore 950 hexacopter, and monoscopic and stereoscopic true-colour and false-colour- composite images (1.84 × 1.84 m resolution) taken by the WorldView-2 satellite.”

Introduction
Line 48 > ‘to support’ should be changed to ‘supporting the installation of…’
Line 52 to 58 > “…through field surveys (Santangelo et al., 2010) or the heuristic visual interpretation of monoscopic or stereoscopic aerial or satellite images (Brardinoni et al., 2003; Fiorucci et al., 2011; Ardizzone et al., 2013), of LiDAR-derived images (Ardizzone et al., 2007; Van Den Eeckhaut et al., 2007; Haneberg et al., 2009; Giordan et al., 2013; Razak et al., 2013; Niculita et al., 2016, Petschko et al., 2016 ), or of ultra-resolution images acquired by Unmanned Aerial Vehicles (UAV, Niethammer et al., 2010, Giordan et al., 2015a, 2015b; Torrero et al., 2015, Turner et al., 2015).
Line 59 > of the mentioned parameters, which are photographic characteristics, and which ones are morphological? Please explain, also considering that one of the main findings of this work is that a photographic landslide signature is best mapped with higher resolution images, while morphometric signatures are better identified with stereoscopic images.
Line 66 > maps prepared to exploit one or more of the mentioned techniques are inevitability incomplete. Is that true? Shouldn’t we affirm that they “can be” incomplete, rather than making such a strong statement?
Line 76 > ‘images of different types’ > ‘images from different sources’
Line 77 > as I mentioned in the abstract, technically you do not compare eight maps, but rather seven maps. The dGPS is the ground truth.
Line 80 > on board OF a UAV.

Study area
Line 96 > “and A third located…”

Image acquisition
What software has been used for the SFM technique?
Line 124: “i.e. the same day…” does not make sense. The same day is not an example, thus, i.e. is not needed

Landslide mapping
Again, you do not compare eight maps. You compare seven maps and use one survey as a benchmark.
Line 147: i.e. is overused. ‘who carried out the field activities (the reconnaissance field mapping and the RTK-DGPS survey) were not involved…”

Field mapping
Line 173 again overuse of ‘i.e.’ > the figure is not an example

Mapping through images
Line 201 again overuse of i.e. > the TC and FCC images are not an example of the images used. They are indeed the images used.
Why the need of draping the UAV image to google earth? The survey itself allows for the creation of a DSM, why using further sources (google) to interpret the images?

Results.
Lines 235-238: I disagree. Visually, Fig. 5F is not that different from 5G or H: F underestimates the lower part of the landslide and misses some features in the top part. I would say that visually the most similar is 5E.

Discussion
Lines 318 to 332 are not needed: they are a summary of what has already been said before.
I think the whole chapter until line 397 can be shortened because much of it is a repetition of the previous one. The authors should focus more on either explaining the numbers or discussing them in general as compared to other works or examples.

Concluding remarks
Lines 457-468 are not needed. All of this has already been explained throughout the manuscript.
Line 465-47 should also be mentioned in the study area description, explaining what photographic and morphological signatures are.
There is no need to explain the results as a list (First….second…third), unless the authors make a short bullet point list of the main findings, and then further discuss them.
Line 512 and following. This whole part can be rephrased without using the personal point of view (e.g. We maintain, We emphasise…’
You can simply state that ‘although the study was conducted on a single landslide, the findings are general and… […]. The technique and imagery used to prepare landslide inventory maps should be selected depending on…”

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ED: Publish subject to minor revisions (review by editor) (21 Nov 2017) by Paolo Tarolli

AR by Federica Fiorucci on behalf of the Authors (01 Dec 2017) Author's response Manuscript

ED: Publish as is (13 Dec 2017) by Paolo Tarolli

AR by Federica Fiorucci on behalf of the Authors (19 Dec 2017)

Short summary

This paper describes the criteria for the optimal selection of remote sensing images to map event landslides, discussing the ability of monoscopic and stereoscopic VHR satellite images and ultra-high-resolution UAV images to resolve the landslide photographical and morphological signatures. The findings can be useful to decide on the optimal imagery and technique to be used when planning the production of a landslide inventory map.