Detection of Pine Shoot Beetle (PSB) Stress on Pine Forests at Individual Tree Level using UAV-Based Hyperspectral Imagery and Lidar

Round 1

Reviewer 1 Report

The article presents the use of Hyperspectral and lidar data from UAV to detect pine damage by the pine shoot beetle. The issue is important in the context of the early detection of insect invasion to prevent their spread. The authors conducted interesting comparative studies, assessed the effectiveness of detection of various degrees of damage using: 1. hyperspectral data, 2. lidar data, and 3. both type of data. The authors proposed also interesting approach to extract three dimensional shadow distribution of each tree crown based on lidar point cloud and the 3D radiative transfer model RAPID.

Comments and suggestions:

The text of the article should be read carefully, because there are letter mistakes, sometimes there are missing dots at the end of a sentence (e.g. Line 135), instead of commas there are dots (e.g. Line 200), sentences begin with a lowercase letter (Line 166). Some sentences require reconstruction or clarification (Lines: 168-169). What does it mean “... separate ground and non-ground ...“.

I suggest using the terms: "lidar variant", "hyperspectral variant", "combined variant"  or "combined approach", "lidar approach", "hyperspectral approach".

No relevant captions under some figures, e.g. Figure 1. Does Figure 1 really show “UVA-based hyperspectral and lidar data collection”?

It is not clear what is presented in the Figure 10. What is compared? Are the figure (a) and the small rectangle in the figure (b) the same area? If so, why is the number of points so different?

Line 75: in my opinion should be "mulitspectral" (not "multi-band")

Line 135: collections?

Line 141: grammatical error in the sentence

Line 304-309: red colour of the text

Line 358: should be "variables"

Author Response

Please see the attachment

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript is correctly written. Please take care when write scientific names and  replace wherever in the text "spp"[italic] to plain text "spp.".

Very interesting study.

Can you explain in Fig 5b how come HI estimation overestimated Cab at low values (i.e. never measured below 25) and when estimating SDR in Fig 8b it underestimated SDR again always below 25% SDR?

Author Response

Dear reviewer

      Thanks for your comments concerning our manuscript entitled "Detection of pine shoot beetle (PSB) stress on pine forests at individual tree level using UAV-based hyperspectral imagery and lidar" (remotesensing-615080). These comments are valuable and helpful for improving our paper. We have studied the comments carefully and have made one by one corrections which we hope can meet with your approval.

      Please see the attachment.

Author Response File: Author Response.docx

Reviewer 3 Report

My general remark:

Estimation of Shoot Damaged Ratio, presented in chapter 3.3, is not clear:

HI program: there are no samples representing dead trees and only one sample representing damaged tree – see Fig.8b It seems that some of the data (HI and lidar) was removed while modelling "combined program" – See a comparison of Fig a and Fig b with Fig c. Does this mean that the authors selected only the best matching data (samples) from both measurements? Theoretically, the inclusion of the data presented in Fig. 8b should worsen the results presented in Fig. 8c

I would like to ask the authors for a more thorough explanation

 

Some minor remarks and comments below:

Lines (23-24) – R2 higher for lidar, so lidar performed better // please check

Lines (304-309) – red text (!)

Lines 317 and 318 - please replace R2 with R²

Figure 5  - authors pointed out overestimation of Cab below 35 ug/cm2 in case of lidar, but Figure 5a shows general overestimation for this range in case of hyperspectral – in my opinion, this result should be interpreted as the evidence of impossibility detection Cab (with values lower than ~30)

Line 327 – for me the differences are evident in the red edge and NIR. Of course, the functions are similar to other results of plant health/condition tests

Lines 328 – 334 – The authors tested many lidar and hyperspectral metrics (tab. 3 and 4), but the results are scarcely discussed.

Figure 6. Interpretation of results from part "b" of figure 6 should lead to the conclusion that SDR detection is practically impossible using lidar.

Author Response

Dear reviewer

      Thanks for your comments concerning our manuscript entitled "Detection of pine shoot beetle (PSB) stress on pine forests at individual tree level using UAV-based hyperspectral imagery and lidar" (remotesensing-615080). These comments are valuable and helpful for improving our paper. We have studied the comments carefully and have made one by one corrections which we hope can meet with your approval.

      Please see the attachment.

Author Response File: Author Response.docx