added reviewed version of paper

tex_review/review/01_review.txt

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+Reviewer #1:
+
+The paper presents a smartphone-based localization system using a particle filter to incorporate different probabilistic models. The comments and suggestions as follows:
+
+1. The authors mention that "a setup-time of under 120 min for the complete building" in abstract. But I don't find any context about the setup-time in the whole paper. How does the "under 120 min" calculate? How long does the navigation mesh for the whole buliding take? How long does the 42 WiFi beacon installation take? How does the measuremnet of the reference points take? etc. The authors should give the details.
+-> 120 museum has enough power outlets, requires it for the vitrinen... (am anfang von den experimenten was dazu schreiben)
+
+2. The authors mention that the historical buildings "environments that are not built with localization in mind or do not provide any wireless infrastructure". But the WiFi beacons still need to be plugged into the power outlets. That means the whole building need 42 available power outlets. Does the WiFi beacon install in special position? I think the historical buildings don't have enough power outlets or the power outlets don't be available in a suitable position, maybe there is no power outlets at all in the whole corridor for example. 
+
+3. The authors meation that "This leads to problems for methods using received signal strengths indications (RSSI) from Wi-Fi or Bluetooth, due to a high signal attenuation between different rooms". However the WiFi beacon this paper used will meet the same issues, the authors also use the RSSI of the WiFi beacons? How does the WiFi beacon avoid the high signal attenuation between different rooms?
+-> We clarified this statement within the text. The text passage you mentioned should not refer to the beacons, but to our used optimization method, see line xxx to xxx. As you correctly stated, the beacons are not able to avoid high signal attenuation. However, as they are very cheap (less then 10 $), we are able to increase the coverage by identifying weak spots. This makes the localization system a bit more independent, e.g. if some building should provide its own Wi-Fi infrastructure. 
+
+4. The authors mention that an optimization scheme can avoid inaccuracies that "outdated fingerprints caused by changes of the environment or inaccurate building plans". However the paper also use the recent RSSI measurements of nearby AP’s and signal strength predictions and "Each reference location was scanned 30 times (≈ 25 s scan time) using a Motorola Nexus 6 at 2.4 GHz band only". How can the reference poits to deal with the changes of the environment? Only 25 scan for each poit at the setup? I can't find any special details to deal with the environment changing issues.
+-> Thank you very much for pointing this out. Your concerns are valid. This was a misformulation within the introduction of the paper. We have improved the relevant section of the text and made the basic statement clearer. Please refer to line xxx and xxx.
+
+5. The author mention that "Such buildings are often full of nooks and crannies, what makes it hard for dynamical models using any kind of pedestrian dead reckoning (PDR)","the error accumulates not only over time, but also with the number of turns and steps made". So "Thus, this paper presents a robust but realistic movement model using a three-dimensional navigation mesh based on triangles". However, Why does the three-dimensional navigation mesh can deal with the turns and steps error? The author should give the more detail description. The navigation graph uses 30*30 grid-cell, the navigation mesh uses triangles. But I don't find very clear that how does the triangles plan? More triangles can improve the accuracy or not? Why the the ground floor need 320 triangles? This the minimum?
+
+6. The authors emphasize that "The goal of this work is to propose a fast to deploy and low-cost localization solution, that provides reasonable results in a high variety of situations". But for the 2500m2 building they used 42 WiFi beacon. I don't think the number is few. Is the whole 42 beacon necessary? The author should discuss the impact of the number of WiFi beacon. How many are the reference poits? What's the impact of the density of the reference points? If the authors want to emphasizen the fast deploy and low-cost, they should give more detail discussion, also the "high variety".
+-> 2500m2 sind nur die bereiche in denen gelaufen werden kann. ohne den innenhof. die zahl ist also etwas verwirrend... 

tex_review/review/02_review.txt

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+Overall:
+
+From my point of view, it is not clear that this paper represents a novel contribution. Almost all the bases and formulation have been presented in your previous paper (IPIN 2016, FUSION 2016, ISPRS International Journal of Geo-Information 2017). Only the KDL optimization and a the trials in a new environment are novels, and they obtained better results due to the floor adaptation of the WAF model.
+-> To clarify the contributions of this work, we have added a listing in lines xxx to xxx. We hope that this will help to provide a better overview.
+
+Detailed comments:
+
+line 187: The smoothing Monte Carlo filter is the same of you proposed in IPIN 2016 conference? It is not clear why you are referring it as Condensation. Are you using any concrete Condensation implementation (OpenCV, matlab,...), and this is the explanation?.
+
+Condensation filter is used in the field of visual tracking due to the researchers do not access to the agent information. In your case you have access to the phone sensors, therefore the concept is a Monte Carlo Localization with transitions detection based on steps and orientation detection.
+
+Using a MCL you do not need to mix observations and actions in the same concept (eq 3.), you should divide into observations and transitions.  
+
+From my point of view formulation of transition model T should be tackled using actions (steps) and observations (s_wifi) should be used like an observation model V (described like "Evaluation" in section 5).
+
+line 226: What is z_t? Is an observation o_t? nomenclature should be unified through the whole paper
+
+line 319: Are these thresholds able for all of pedestrians? have you tried with different actors and behaviors?
+
+line 410: Why 10.000 samples in the building? Should it be dependent of the building size, wifi noise, etc...?
+
+line 480: In line 410 you propose 10.000 particles and in the experiments propose 1.000, why?
+
+line 508: results shown in Figure 3 are not clear presented, from my point of view the proposal seems to be worse than the previous one, there are much more outliers (blue color)
+
+line 512: typo "prober"
+
+Figure 5: It is not clear connections between ground floor and first floor, is there any typo or figures are misplaced?
+
+Figure 6: You use the expression "Monte Carlo", are you referring to Condensation?
+
+Results section: results and comments are ad-hoc for this environment, and it is not demonstrated that could be applied in a more general context.
+
+
+

tex_review/review/03_review.txt

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+The paper presents an improvement to a previous work of the authors where a transition, model, an activity recognition method, a recovery method for the particle filter, and an improved density estimation.
+
+The novelty of the paper was collected in the reading and it should be more clearly listed. At the current status of the paper it is not clear. It should be itemized in the abstract and also in the obtained results.
+-> Thank you very much for this advice. We tried to clarify this within the abstract as well as at the end of the introduction (see line xxx to xxx). We further added a discussion to the results,  which addresses the contributions and their impact on the system. 
+
+The rapid computation declaration is not proven, given that the authors do not compare the non-gridded approach timings.
+-> The terminology "rapid computation scheme" only refers to the state estimation process, not the underlying graph or the complete system performance. It seems this is not clearly formulated within the paper. The weighted-average estimator yields faster estimates of the position compared to the KDE approach as we have shown in our previous work .... This previous work does also provide an extensive comparison between other state-of-the-art KDE approximations. 
+However, if you refer to the comparison between gridded graph and navigation mesh, ...
+Nevertheless, ...
+
+Does the system will also work in regular buildings? A final comment on the lessons learned in this case of the 13th century building should be in the conclusions, given that the title focus on this very specific context.
+-> 
+
+From the middle of the paper the quality of the English decreases with several sentences with errors, some of them were identified.
+->
+
+Given that the authors declare that this is an update they should be more clear on what was already done. We also consider that the authors use auto citation excessively (7 in 32) and or compress the self-citation or increase the comparison with other works.
+->
+
+The paper is relevant and should be published after a clarification on the produced work and at least report two comparisons, one in the performance of the KDE and other on the initialization time.
+->
+
+Some notes follow along the lines of the paper:
+
+ 
+
+Ln 1- "of our award-winning" 

+
+The authors should refrain to be excessive in the connotation of the work, at least in the abstract. Should not hide but can declare the award in a more soft way.
+-> We have removed the remark and have formulated the remaining text passages more modestly.
+
+Ln 9-…
+
+"Continuous and smooth floor changes are enabled by using a simple activity recognition. Our rapid computation scheme of the kernel density estimation allows to find an exact estimation of the pedestrian’s current position. We further tackle advanced problems like multimodal densities and sample impoverishment (system gets stuck) by introducing different countermeasures, leading to a more robust localization. 
" Too many adjectives without justification: simple, rapid, advanced...
+-> You are right and we have rewritten the particular text-block. 
+
+Ln 14: Why low cost solution? Are the material less expensive compared to what alternative? If the authors do not want to defend this property we suggest it should be removed. (also in Ln 64)
+-> The argument that our system is inexpensive is based on several considerations: With under 10 dollars per piece the Wi-Fi beacons are very cheap compared to conventional access points. 
+They only require a power source in order to operate, which keeps the need for additional infrastructure small. Furthermore, we believe that a janitor is able to set up our system independently. This means that there is no need to pay an external contractor to utilize the system and only the hardware costs and, if applicable, the price of the software have to be calculated. Nevertheless, as you suggested correctly, these considerations could not apply to all buildings and scenarios, which is why the property "low cost" is removed. 
+
+Ln 21: “optimization scheme enables a setup-time of under 120 min for the complete building. 
”- Should indicate the mapped area.
+-> Fixed in line 26. 
+
+Ln 38: “There is also a higher chance of detecting false or misplaced turns,”
+The sentence appears incorrect
+-> Fixed in line 43.
+
+Ln 40: “presents a robust but realistic movement”
+Too many adjectives not explained
+-> Fixed in line 45.
+
+Ln 52: "This leads to problems for methods..." This phrase should be reformulated since Wi-Fi fingerprinting is RSSI based and might actually benefit from the high signal attenuation between different rooms. The problem is probably coverage of the whole building, not parameter estimation. 
+-> This line was written with signal strength prediction models in mind, which is wrong in terms of fingerprinting, of course. Thank you for the hint! We tried the incorporate both, coverage and parameter estimation between line xxx and xxx.
+
+Ln 58 of simple and cheap- How simple and how cheap?
+-> The price mostly depends on the reseller, ranging from 3 dollar to 10 dollar. The term "simple" is of course difficult to substantiate, which is why it was removed. 
+
+Ln 160 “are based on the nature of particle filter.” -> “are based on the nature of a particle filter.” 
+-> Fixed in line 180.
+
+Ln 215: "Using variable shaped/sized elements instead of rigid grid-cells provide both higher accuracy for reaching every corner, and ..." Is accuracy the right word here?
+-> TODO: @Frank
+
+Ln 228: "If the destination is unreachable, e.g. due to the walls or other obstacles." This phrase is incorrect, the authors should reformulate it.
+-> TODO: Echt? Haben wir in der Intro oben auch. Warum ist das falsch?
+
+Ln 237: "...the average acceleration..." This includes both linear acceleration and gravity, use "linear acceleration".
+-> TODO: @Frank?
+
+Ln 258 -  This equation needs revision. Should it be "p(s_i|p)  ~ N(u_i,p , std²_wifi)" ? Also the wall-attenuation-factor-model only takes into account attenuation by floors, not walls.
+-> TODO: Eigentlich passt das mit der NV, für Ihn tdz ändern? Und das model nimmt keine wände, weil wir keine wände nehmen :D. 
+
+Ln 271-272: The authors mention that their WiFi fingerprinting approximation process is faster than classical fingerprinting, but they fail to provide a reference for an example of the latter or significant metrics such as the average time per square meter for fingerprinting a whole building. Furthermore, the authors should also take into account that while there are approaches where reference measurements are recorded on small grids between 1 to 2m, there are also approaches able to record reference measurements using faster methods. One example is walking by the building while registering ground truth points and using dead reckoning techniques (see Guimarães, V. et al. A motion tracking solution for indoor localization using smartphones. In Proceedings of the 2016 International Conference on Indoor Positioning and Indoor Navigation (IPIN)).
+-> TODO: vielleicht den satz hier entfernen und im related work darauf hinweisen, dass es auch andere schnelle ansätze gibt? Wobei wir im related work schon [20] gecited haben, der genau das macht! vielleicht erwähnen wir seinen noch, damit er zufrieden ist? Oder wir zeigen das kleine fingerprints schneller ist als laufen? was vermutlich nicht der fall ist. 
+
+Ln 275 - Equation 9 The d0 parameter of eq.8 shpuld also be presented in eq.9.
+-> Fixed in line xxx
+
+Ln 307 “Activity Recognition ” The threshold approach should have reports on the detection capability
+-> TODO: Also die pfade nochmal berechnen und da die erkennungsrate ausspucken.
+
+Ln 316 - Equation 10 According to these rules a user could be standing and walking at the same time. The algorithm would be better represented by a flowchart or a decision tree.
+-> You are right. Standing and walking at the same time should not supposed to be happen. We exchanged the equation with a decision tree. In our opinion the algorithm is now very easy to understand, thank you for the good advice. 
+
+Ln 316: t_baro = 0.042 m/s² ? Wrong unit, please confirm value and unit again.
+-> Of course, m/s² is the wrong unit for pressure. Changed to hPa.
+
+Ln 360 “It is obvious, that a computation of the probability density function of the posterior could solve the above, but finding such an analytical solution is clearly an intractable problem, which is the reason for applying a sample representation in the first place.” The authors should refrain to make non scientific comments like “obvious” or “clearly”. Do direct statements. 
+-> The objection is valid and we will fix the appropriate text passages.
+
+Ln 381 “Our rapid computation scheme” – As commented before. Be more concrete and remove non justified adjectives.
+-> As before, the adjective "rapid computation" was removed in behalf of approximation scheme.
+
+Ln 453 “By utilizing it to a 13th century historic building”-> “By utilizing the proposed technology in a 13th century historic building”
+-> Fixed as recommended. 
+
+Ln 469: "8 cores..." The i7-4702HQ has 4 cores and 8 threads, not 8 cores.
+-> This misstatement has been fixed.
+
+Ln 551  - “above are more moderately attenuated” revise.
+-> More understandable and correctly formulated in line xxx.
+
+Ln 524 - Figure 4 "...xz plane..." should be xy plane
+-> Fixed. 
+
+Ln 578 “This allows us to discuss everything in detail” – irrelevant or should be better expressed.
+-> Removed.
+
+Ln 711 -  “The KDE-based estimation illustrates this behavior very accurate” – Revise
+-> This sentence was very daring and incomprehensible. We tried to explain the situation in greater detail. Please refer to lines xxx to xxx.
+
+Ln 713 – “the teal square” – It is not a square.
+-> Replaced throughout the whole work by rectangle, area or border depending on the use. 
+
+Ln 720 – “In the end, it is a question of optimal harmony between transition and evaluation.” This is sentence is not providing information and lacks scientific objectivity.
+-> The sentence was removed, as it was irrelevant.
+
+Ln 726 “At the end, in the here shown examples we only searched for a global maxima” – revise english
+
+
+Ln 733 – “Compared to other state-of-the-art solutions, the setup time is only a few hours and does not require any expert knowledge or hardware.” This comparision is not done in the paper. The authors should be more specific given that this property of the purposed system is declared important, and so should be given with ore detail and (m^2 per hour) and compared with the coverage time of other systems.
+
+Ln 754 – “opens up completely new possibilities when” – revise tone of writing.