Mobile Laser Scanning Data Collected under a Forest Canopy with GNSS/INS-Positioned Systems: Possibilities of Processability Improvements
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript evaluated the influence of point cloud parameters, GNSS availability, and GNSS signal strength on the optimal bin width representing the processability of the point cloud. The results would help the users of MLS improve point cloud processability by choosing different mapping patterns and a better GNSS satellite constellation. The discussion section was rather reviews on the latest and advanced technology. Comparing methods and results of this study with those of the existing studies would be recommended in the discussion section.
Author Response
Reply is in enclosed file
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe topic is current and certainly interesting to the readers of the Remote Sensing magazine, and especially to the forestry profession. The work is quite extensive, so I suggest that it be reduced a little, especially the introduction, and reduce some description in the methodology. I had really small remarks that are listed in the comments of the .pdf document.
Comments for author File: Comments.pdf
Author Response
Reply is in enclosed file
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe contribution analyzes the potential for increasing applicability for positioning of vehicle-mounted mobile lidar-based mapping systems in conditions under forest canopy cover with poor sensor localization using GNSS/INS devices.
The research is innovative and original in its focus on verifying the influence of the acquisition conditions (GNSS outage, signal strength, point cloud parameters, plot's occlusion) on the benefit results of specific temporal clustering on unaligned point clouds - which would represent a robust and efficient preprocessing technique for handling large MLS point clouds.
Although methods of lidar point clouds utilization in forestry are in general already very well developed, even including automated stems and tree crowns segmentation, it is assumed that their components are precisely located and aligned. However, in practice, this assumption is very difficult to achieve with mobile scanners in forest conditions (using GNSS/INS localization).
Aiming to verify the effect of acquisition conditions on the future processability of the lidar point cloud, which was preprocessed using specific temporal-based clustering to align cloud components, is then valuable and interesting, with prospective potential to contribute to stimulating research into the application of such devices in forestry.
Quality of the presentation is good. Contribution is written in an understandable style, and the structure of manuscript is suitable.
Readability of the submitted work is somewhat obscured by the continuity of its content with the method originally developed and applied in the previous author's work - Čerňava et al, 2017. I recommend the authors to check this issue and pay attention to the explicit explanation in relevant passages of the text (introduction, methodology and discussions section).
In the methodology section, I recommend adding references confirming the correctness of the applied statistical analysis procedures.
In the discussion section (line 716 – 727), I do not consider it correct to refer only to the work of Čerňava et al 2017, but mainly to the content of the presented research. I also consider it appropriate to add specifically forestry examples of the application of time-based clustering in the preprocessing of lidar point clouds (line 688-700).
Conclusions are consistent with the evidence and arguments presented. They are functional, practical, justified, and I consider the results sufficiently and clearly interpreted.
References used are, to the best of my knowledge, appropriate and up-to-date. The number of references is high, but their selection and the approach used to comments support the understanding of the wider context in which this research is anchored.
Tables and figures contribute to the understanding of the commented facts and are of adequate graphic quality.
I consider the design of the experiments correct. The study uses proven and accepted approaches, data, methods, tools, etc. It is also fully reproducible, even if the data collection conditions are variable.
The results can be interesting for RS readers. I recommend publishing this manuscript after minor revisions.
Author Response
Reply is in encloswed file
Author Response File: Author Response.pdf
Reviewer 4 Report
Comments and Suggestions for AuthorsThe authors of "Mobile laser scanning data collected under a forest canopy with GNSS/INS positioned systems: Possibilities of processability improving" investigate occlusion and GNSS outage limitations under variable forest canopy densities. Most of the findings are intuitive, except the increased occlusion/bin size finding that would make dense forests more advantageous for preprocessing. This alone is worth reporting. Studies like this will undoubtably lead to improvements in operational use of MLS as a forestry measurement tool.
In general, the language in this manuscript is dense. It could benefit from shorter sentence structure, and a reduction in the size of the results. There are several sentences that are more fitting in the discussion. The introduction and methods sections are adequate and there are no issues with methodology, analyses or interpretation of results.
A few comments that would improve the manuscripts are below:
Lines 37-38: how is PLS different from MLS? Both employ SLAM. The technology used in a backpack/vehicle mounted system is the same as handheld. It seems like a weird distinction. Consider lumping them into MLS so that the field does not continue to make unnecessary distinctions.
Figure 10 is labeled as figure 9.
Several citations are in the lit cited, but not in the text, including 175, 181-190. Please address this.
Comments on the Quality of English LanguageThere are several minor issues with the clarity of language. This manuscript would benefit from an editing of the English, including in the title. Improvements should replace improving.
Author Response
Reply is in enclosed file
Author Response File: Author Response.pdf
