Complete comments

1-introduction/introduction.tex

@@ -5,9 +5,9 @@
 
 \bigskip
 
-\comans{JG}{I was wondering what the difference between an immersive AR headset and a non-immersive AR headset should be. If there is a difference (e.g., derived through headset properties by FoV), it should be stated. If there is none, I would suggest not using the term immersive AR headset but simply AR headset. On this account, in Figure 1.5 another term (“Visual AR Headset”) is introduced (and later OST-AR systems, c.f. also section 2.3.1.3).}{The terms "immersive AR headset" and "visual AR headset" have been replaced by the more appropriate term "AR headset".}
 In this manuscript thesis, we show how \AR headset, which integrates visual virtual content into the real world perception, and wearable haptics, which provide tactile sensations on the skin, can improve direct hand interaction with virtual and augmented objects.
 Our goal is to enable users to perceive and interact with wearable visuo-haptic augmentations in a more realistic and effective way, as if they were real.
+\comans{JG}{I was wondering what the difference between an immersive AR headset and a non-immersive AR headset should be. If there is a difference (e.g., derived through headset properties by FoV), it should be stated. If there is none, I would suggest not using the term immersive AR headset but simply AR headset. On this account, in Figure 1.5 another term (“Visual AR Headset”) is introduced (and later OST-AR systems, c.f. also section 2.3.1.3).}{The terms "immersive AR headset" and "visual AR headset" have been replaced by the more appropriate term "AR headset".}
 
 \section{Visual and Haptic Object Augmentations}
 \label{visuo_haptic_augmentations}
@@ -123,6 +123,8 @@ The \textbf{integration of wearable haptics with \AR headsets appears to be one
 \section{Research Challenges of Wearable Visuo-Haptic Augmented Reality}
 \label{research_challenges}
 
+\comans{SJ}{The chapter could benefit from some expansion. For instance, the current introduction tries to describe the scope of the research in haptic AR but lacks sufficient background on the general issues in this domain. As a result, it may not be very helpful for readers unfamiliar with the field in understanding the significance of the thesis's focus and positioning it within the broader context of haptic AR research.}{TODO}
+
 The integration of wearable haptics with \AR headsets to create a visuo-haptic \AE is complex and presents many perceptual and interaction challenges.
 In this thesis, we propose to \textbf{represent the user's experience with such a visuo-haptic \AE as an interaction loop}, shown in \figref{interaction-loop}.
 It is based on the interaction loops of users with \ThreeD systems \cite[p.84]{laviolajr20173d}.
@@ -140,6 +142,8 @@ In this context, we focus on two main research challenges:
 \textbf{(I) providing plausible and coherent visuo-haptic augmentations}, and
 \textbf{(II) enabling effective manipulation of the \AE}.
 Each of these challenges also raises numerous design, technical, perceptual and user experience issues specific to wearable haptics and \AR headsets.
+\comans{JG}{While these research axes seem valid, it could have been described more clearly how they fit into the overarching research fields of visuo-haptic augmentations.}{TODO}
+
 \footnotetext{%
   The icons are \href{https://creativecommons.org/licenses/by/3.0/}{CC BY} licensed:
   \enquote{\href{https://thenounproject.com/icon/finger-pointing-4230346/}{finger pointing}} by \href{https://thenounproject.com/creator/leremy/}{Gan Khoon Lay},

2-related-work/2-wearable-haptics.tex

@@ -183,7 +183,7 @@ The integration of the real and virtual sensations into a single property percep
 In particular, the visual rendering of a touched object can also influence the perception of its haptic properties, \eg by modifying its visual texture in \AR or \VR, as discussed in the \secref{visuo_haptic}.
 
 \textcite{bhatia2024augmenting} categorize the haptic augmentations into three types: direct touch, touch-through, and tool-mediated.
-In \emph{direct touch}, the haptic device does not cover the inside of the hand so as not to impair the user's interaction with the \RE, and is typically achieved with wearable haptics.
+In \emph{direct touch}, the haptic device does not cover the inside of the hand so as not to impair the interaction of the user with the \RE, and is typically achieved with wearable haptics.
 In touch-through and tool-mediated, or \emph{indirect feel-through} \cite{jeon2015haptic}, the haptic device is placed between the hand and the \RE.
 %We are interested in direct touch augmentations with wearable haptics (\secref{wearable_haptic_devices}), as their integration with \AR is particularly promising for free hand interaction with visuo-haptic augmentations.
 Many haptic augmentations were first developed with touch-through devices, and some (but not all) were later transposed to direct touch augmentation with wearable haptic devices.

2-related-work/3-augmented-reality.tex

@@ -144,6 +144,8 @@ Choosing useful and efficient \UIs and interaction techniques is crucial for the
 
 \textcite{laviolajr20173d} (p.385) classify interaction techniques into three categories based on the tasks they enable users to perform: manipulation, navigation, and system control.
 \textcite{hertel2021taxonomy} proposed a similar taxonomy of interaction techniques specifically for \AR headsets.
+\comans{JG}{In, Figure 2.24 I suggest removing d. or presenting it as separate figure as it shows no interaction technique (The caption is “Interaction techniques in AR” but a visualization of a spatial registration technique).}{It has been removed and replaced by an example of resizing a virtual object.}
+In this thesis we focus on manipulation tasks of virtual content directly with the hands, more specifically on touching visuo-haptic textures with a finger (\partref{perception}) and positioning and rotating virtual objects pushed and grasp by the hand (\partref{manipulation}).
 
 The \emph{manipulation tasks} are the most fundamental tasks in \AR and \VR systems, and the building blocks for more complex interactions.
 \emph{Selection} is the identification or acquisition of a specific virtual object, \eg pointing at a target as in \figref{grubert2015multifi}, touching a button with a finger, or grasping an object with a hand.
@@ -157,9 +159,6 @@ Wayfinding is the cognitive planning of the movement, such as path finding or ro
 
 The \emph{system control tasks} are changes to the system state through commands or menus such as creating, deleting, or modifying virtual objects, \eg as in \figref{roo2017onea}. It is also the input of text, numbers, or symbols.
 
-\comans{JG}{In, Figure 2.24 I suggest removing d. or presenting it as separate figure as it shows no interaction technique (The caption is “Interaction techniques in AR” but a visualization of a spatial registration technique).}{It has been removed and replaced by an example of resizing a virtual object.}
-In this thesis we focus on manipulation tasks of virtual content directly with the hands, more specifically on touching visuo-haptic textures with a finger (\partref{perception}) and positioning and rotating virtual objects pushed and grasp by the hand (\partref{manipulation}).
-
 \begin{subfigs}{interaction-techniques}{Interaction techniques in \AR. }[][
   \item Spatial selection of virtual item of an extended display using a hand-held smartphone \cite{grubert2015multifi}.
   \item Resizing a virtual object with a bimanual gesture \cite{piumsomboon2013userdefined}.

3-perception/vhar-system/1-introduction.tex

@@ -2,17 +2,20 @@
 \label{intro}
 
 One approach to render virtual haptic textures consists in simulating the roughness of a periodic grating surface as a vibrotactile sinusoidal (\secref[related_work]{texture_rendering}).
-The vibrations are rendered to a voice-coil actuator embedded in a hand-held tool or worn on the finger, but to create the illusion of touching a pattern with a fixed spatial period, the frequency of signal must be modulated according to the finger movement.
+The vibrations are rendered to a voice-coil actuator embedded in a hand-held tool or worn on the finger (\secref[related_work]{vhar_haptics}).
+To create the illusion of touching a pattern with a fixed spatial period, the frequency of signal must be modulated according to the finger movement.
 Previous work either used mechanical system to track the movement at high frequency \cite{strohmeier2017generating,friesen2024perceived}, or required the user to move at a constant speed to keep the signal frequency constant \cite{asano2015vibrotactile,ujitoko2019modulating}.
 However, this method has not yet been integrated in an \AR headset context, where the user should be able to freely touch and explore the visuo-haptic texture augmentations.
 
 %which either constrained hand to a constant speed to keep the signal frequency constant \cite{asano2015vibrotactile,friesen2024perceived}, or used mechanical sensors attached to the hand \cite{friesen2024perceived,strohmeier2017generating}
 
 In this chapter, we propose a \textbf{system for rendering visual and haptic virtual textures that augment real surfaces}.
-It is implemented with the \OST-\AR headset Microsoft HoloLens~2 and a wearable vibrotactile (voice-coil) device worn on the outside of finger (not covering the fingertip, \secref[related_work]{vhar_haptics}).
-The visuo-haptic augmentations can be \textbf{viewed from any angle} and \textbf{explored freely with the bare finger}, as if they were real textures.
+It is implemented with the \OST-\AR headset Microsoft HoloLens~2 and a wearable vibrotactile (voice-coil) device worn on the outside of finger (not covering the fingertip).
+The visuo-haptic augmentations rendered with this design allow a user to \textbf{see the textures from any angle} and \textbf{explore them freely with the bare finger}, as if they were real textures.
 To ensure both real-time and reliable renderings, the hand and the real surfaces are tracked using a webcam and marker-based pose estimation.
 The haptic textures are rendered as a vibrotactile signal representing a patterned grating texture that is synchronized with the finger movement on the augmented surface.
+The goal of this design is to enable new \AR applications capable of augmenting real objects with virtual visuo-haptic textures in a portable, on-demand manner, and without impairing with the interaction of the user with the \RE.
+\comans{SJ}{The rationale behind the proposed design is not provided. Since there are multiple ways to implement mechanically transparent haptic devices, the thesis should at least clarify why this design is considered optimal for a specific purpose at this stage.}{This has been better explained in the introduction.}
 
 \noindentskip The contributions of this chapter are:
 \begin{itemize}

3-perception/vhar-system/2-method.tex

@@ -47,7 +47,6 @@ Finally, this filtered finger velocity is transformed into the augmented surface
 \subsection{Virtual Environment Registration}
 \label{virtual_real_registration}
 
-\comans{JG}{The registration process between the external camera, the finger, surface and HoloLens could have been described in more detail. Specifically, it could have been described clearer how the HoloLens coordinate system was aligned (e.g., by also tracking the fiducials on the surface and or finger).}{This has been better described.}
 Before a user interacts with the system, it is necessary to design a \VE that will be registered with the \RE during the experiment.
 Each real element tracked by a marker is modelled virtually, \eg the hand and the augmented surface (\figref{device}).
 In addition, the pose and size of the virtual textures were defined on the virtual replicas.
@@ -56,12 +55,13 @@ First, the coordinate system of the headset is manually aligned with that of the
 This resulted in a \qty{\pm .5}{\cm} spatial alignment error between the \RE and the \VE.
 While this was sufficient for our use cases, other methods can achieve better accuracy if needed \cite{grubert2018survey}.
 The registration of the coordinate systems of the camera and the headset thus allows the use of the marker estimation poses performed with the camera to display in the headset the virtual models aligned with their real-world counterparts.
+\comans{JG}{The registration process between the external camera, the finger, surface and HoloLens could have been described in more detail. Specifically, it could have been described clearer how the HoloLens coordinate system was aligned (e.g., by also tracking the fiducials on the surface and or finger).}{This has been better described.}
 
-\comans{JG}{A description if and how the offset between the lower side of the fingertip touching the surface and the fiducial mounted on the top of the finger was calibrated / compensated is missing}{This has been better described.}
 An additional calibration is performed to compensate for the offset between the finger contact point and the estimated marker pose \cite{son2022effect}.
 The current user then places the index finger on the origin point, whose respective poses are known from the attached fiducial markers.
 The transformation between the marker pose of the finger and the finger contact point can be estimated and compensated with an inverse transformation.
 This allows to detect if the calibrated real finger touches a virtual texture using a collision detection algorithm (Nvidia PhysX).
+\comans{JG}{A description if and how the offset between the lower side of the fingertip touching the surface and the fiducial mounted on the top of the finger was calibrated / compensated is missing}{This has been better described.}
 
 In our implementation, the \VE is designed with Unity (v2021.1) and the Mixed Reality Toolkit (v2.7)\footnoteurl{https://learn.microsoft.com/windows/mixed-reality/mrtk-unity}.
 The visual rendering is achieved using the Microsoft HoloLens~2, an \OST-\AR headset with a \qtyproduct{43 x 29}{\degree} \FoV, a \qty{60}{\Hz} refresh rate, and self-localisation capabilities.
@@ -125,3 +125,7 @@ The total visual latency can be considered slightly high, yet it is typical for
 The two filters also introduce a constant lag between the finger movement and the estimated position and velocity, measured at \qty{160 \pm 30}{\ms}.
 With respect to the real hand position, it causes a distance error in the displayed virtual hand position, and thus a delay in the triggering of the vibrotactile signal.
 This is proportional to the speed of the finger, \eg distance error is \qty{1.2 \pm .2}{\cm} when the finger moves at \qty{7.5}{\cm\per\second}.
+
+The velocity estimation and delay effects should be examined in more detail, as these
+factors are critical for ensuring the perceptual quality of the system. A 36 ms discrepancy
+between movement and feedback may not be sufficient in all scenarios.

3-perception/vhar-textures/2-experiment.tex

@@ -122,5 +122,5 @@ After each of the two tasks, participants answered to the following 7-item Liker
 
 In an open question, participants also commented on their strategy for completing the \level{Matching} task (\enquote{How did you associate the tactile textures with the visual textures?}) and the \level{Ranking} task (\enquote{How did you rank the textures?}).
 
-\comans{JG}{I suggest to also report on [...] the software packages used for statistical analysis (this holds also for the subsequent chapters).}{This has been added to all chapters where necessary.}
 The results were analyzed using R (v4.4) and the packages \textit{afex} (v1.4), \textit{ARTool} (v0.11), \textit{corrr} (v0.4), \textit{FactoMineR} (v2.11), \textit{lme4} (v1.1), and \textit{performance} (v0.13).
+\comans{JG}{I suggest to also report on [...] the software packages used for statistical analysis (this holds also for the subsequent chapters).}{This has been added to all chapters where necessary.}

3-perception/vhar-textures/3-results.tex

@@ -7,10 +7,10 @@
 \paragraph{Confusion Matrix}
 \label{results_matching_confusion_matrix}
 
-\comans{JG}{For the two-sample Chi-Squared tests in the matching task, the number of samples reported is 540 due to 20 participants conducting 3 trials for 9 textures each. However, this would only hold true if the repetitions per participant would be independent and not correlated (and then, one could theoretically also run 10 participants with 6 trials each, or 5 participants with 12 trials each). If they are not independent, this would lead to an artificial inflated sample size and Type I error. If the trials are not independent (please double check), I suggest either aggregating data on the participant level or to use alternative models that account for the within-subject correlation (as was done in other chapters).}{Data of the three confusion matrices have been aggregated on the participant level and analyzed using a Poisson regression.}
 \figref{results/matching_confusion_matrix} shows the confusion matrix of the \level{Matching} task with the visual textures and the proportion of haptic texture selected in response, \ie the proportion of times the corresponding \response{Haptic Texture} was selected in response to the presentation of the corresponding \factor{Visual Texture}.
 To determine which haptic textures were selected most often, the repetitions of the trials were first aggregated by counting the number of selections per participant for each (\factor{Visual Texture}, \response{Haptic Texture}) pair.
 An \ANOVA based on a Poisson regression (no overdispersion was detected) indicated a statistically significant effect on the number of selections of the interaction \factor{Visual Texture} \x \response{Haptic Texture} (\chisqr{64}{180}{414}, \pinf{0.001}).
+\comans{JG}{For the two-sample Chi-Squared tests in the matching task, the number of samples reported is 540 due to 20 participants conducting 3 trials for 9 textures each. However, this would only hold true if the repetitions per participant would be independent and not correlated (and then, one could theoretically also run 10 participants with 6 trials each, or 5 participants with 12 trials each). If they are not independent, this would lead to an artificial inflated sample size and Type I error. If the trials are not independent (please double check), I suggest either aggregating data on the participant level or to use alternative models that account for the within-subject correlation (as was done in other chapters).}{Data of the three confusion matrices have been aggregated on the participant level and analyzed using a Poisson regression.}
 Post-hoc pairwise comparisons using the Tukey's \HSD test then indicated there was statistically significant differences for the following visual textures:
 \begin{itemize}
   \item With \level{Sandpaper~320}, \level{Coffee Filter} was more selected than the other haptic textures (\ztest{3.4}, \pinf{0.05} each) except \level{Plastic Mesh~1} and \level{Terra Cotta}.

3-perception/xr-perception/3-experiment.tex

@@ -34,12 +34,12 @@ Participants rated the roughness of the paper (without any texture augmentation)
 The visual rendering of the virtual hand and the \VE was achieved using the \OST-\AR headset Microsoft HoloLens~2 running at \qty{60}{FPS} a custom application made with Unity (v2021.1) and Mixed Reality Toolkit (v2.7).
 An \OST-\AR headset was chosen over a \VST-\AR headset because the former only adds virtual content to the \RE, while the latter streams a real-time video capture of the \RE, and one of our objectives was to directly compare a \VE replicating a real one, not to a video feed that introduces many other visual limitations (\secref[related_work]{ar_displays}).
 
-\comans{JG}{In addition, the lag between the real and virtual hand in the Mixed condition could have been quantified (e.g. using a camera filming through the headset) to shed more light on the reported differences, as also noted in Section 4.5, as well as the registration error between the real and the virtual hand (as visible in Figure 4.1, Mixed).}{This has been added.}
 We carefully reproduced the \RE in the \VE, including the geometry of the box, textures, lighting, and shadows (\figref{renderings}, \level{Virtual}).
 The virtual hand model was a gender-neutral human right hand with realistic skin texture, similar to that used by \textcite{schwind2017these}.
 Prior to the experiment, the virtual hand and the \VE were registered to the real hand of the participant and the \RE, respectively, as described in \secref[vhar_system]{virtual_real_registration}.
 The size of the virtual hand was also manually adjusted to match the real hand of the participant.
 A \qty{\pm .5}{\cm} spatial alignment error (\secref[vhar_system]{virtual_real_registration}) and a \qty{160 \pm 30}{\ms} lag (\secref[vhar_system]{virtual_real_registration}) between the real hand the virtual hand were measured.
+\comans{JG}{In addition, the lag between the real and virtual hand in the Mixed condition could have been quantified (e.g. using a camera filming through the headset) to shed more light on the reported differences, as also noted in Section 4.5, as well as the registration error between the real and the virtual hand (as visible in Figure 4.1, Mixed).}{This has been added.}
 
 To ensure the same \FoV in all \factor{Visual Rendering} condition, a cardboard mask was attached to the \AR headset (\figref{experiment/headset}).
 In the \level{Virtual} rendering, the mask only had holes for sensors to block the view of the \RE and simulate a \VR headset.

4-manipulation/visual-hand/5-conclusion.tex

@@ -11,11 +11,11 @@ Our results showed that a visual hand augmentation improved the performance, per
 A skeleton rendering, which provided a detailed view of the tracked joints and phalanges while not hiding the real hand, was the most performant and effective.
 The contour and mesh renderings were found to mask the real hand, while the tips rendering was controversial.
 The occlusion rendering had too much tracking latency to be effective.
-This is consistent with similar manipulation studies in \VR and in non-immersive \VST-\AR setups.
+This is consistent with similar manipulation studies in \VR and in \VST-\AR setups.
 
-This study suggests that a \ThreeD visual hand augmentation is important in \AR when interacting with a virtual hand technique, particularly when it involves precise finger movements in relation to virtual content, \eg \ThreeD windows, buttons and sliders, or more complex tasks, such as stacking or assembly.
+This study suggests that a \ThreeD visual hand augmentation is important in \OST-\AR when interacting with a virtual hand technique, particularly when it involves precise finger movements in relation to virtual content, \eg \ThreeD windows, buttons and sliders, or more complex tasks, such as stacking or assembly.
 A minimal but detailed rendering of the virtual hand that does not hide the real hand, such as the skeleton rendering we evaluated, seems to be the best compromise between the richness and effectiveness of the feedback.
-%Still, users should be able to choose and adapt the visual hand augmentation to their preferences and needs.
+%In addition, users should be able to choose and adapt the visual hand augmentation to their preferences and needs.
 
 In addition to visual augmentation of the hand, direct manipulation of virtual objects with the hand can also benefit from wearable haptic feedback.
 In the next chapter, we explore two wearable vibrotactile contact feedback devices in a user study, located at four positionings on the hand so as to not cover the fingertips.

4-manipulation/visuo-haptic-hand/1-introduction.tex

@@ -10,7 +10,7 @@ Conjointly, a few studies have explored and compared the effects of visual and h
 \textcite{sarac2022perceived} and \textcite{palmer2022haptic} studied the effects of providing haptic feedback about contacts at the fingertips using haptic devices worn at the wrist, testing different mappings.
 Their results proved that moving the haptic feedback away from the point(s) of contact is possible and effective, and that its impact is more significant in the absence of the visual feedback of the virtual hand.
 A final question is whether one or the other of these (haptic or visual) hand feedback should be preferred \cite{maisto2017evaluation,meli2018combining}, or whether a combined visuo-haptic feedback is beneficial for users.
-However, these studies were conducted in non-immersive setups, with a screen displaying the \VE view.
+However, these studies were conducted in setups with a screen displaying the \VE view and not using an \AR headset (\secref[related_work]{ar_displays}).
 In fact, both hand feedback can provide sufficient sensory feedback for efficient direct hand manipulation of virtual objects in \AR, or conversely, they can be shown to be complementary.
 
 In this chapter, we investigate the role of \textbf{visuo-haptic feedback of the hand when manipulating virtual object} using an \OST-\AR headset and wearable vibrotactile haptics.

4-manipulation/visuo-haptic-hand/5-conclusion.tex

@@ -12,8 +12,13 @@ The visual hand augmentation was perceived less necessary than the vibrotactile
 This study provide evidence that moving away the feedback from the inside of the hand is a simple but promising approach for wearable haptics in \AR.
 
 If integration with the hand tracking system allows it, and if the task requires it, a haptic ring worn on the middle or proximal phalanx seems preferable.
-However, a wrist-mounted haptic device will be able to provide richer feedback by embedding more diverse haptic actuators with larger bandwidths and maximum amplitudes, while being less obtrusive than a ring.
-Finally, we think that the visual hand augmentation complements the haptic contact rendering well by providing continuous feedback on the hand tracking, and that it can be disabled during the grasping phase to avoid redundancy with the haptic feedback of the contact with the virtual object.
+It can provide more realistic and appreciated feedback, being closer to the point of contact.
+However, a calibration step seems important to adapt to the individual preferences and sensitivities of the user.
+Yet, a wrist-mounted haptic device will be able to provide richer feedback by embedding more diverse haptic actuators with larger bandwidths and maximum amplitudes, while being less obtrusive than a ring.
+It could thus provide more complex feedback of the contacts with the virtual objects.
+Finally, we think that the visual hand augmentation complements the haptic contact rendering well by providing continuous feedback on hand tracking.
+Such a visual augmentation can be disabled during the grasping phase to avoid redundancy with the haptic feedback of the contact with the virtual object.
+\comans{SJ}{Again, it would strengthen the thesis if the authors provided a systematic guideline on how to choose the appropriate haptic feedback or visual augmentation depending on the specific requirements of an application.}{The guidelines paragraph have been expanded in the conclusion.}
 
 \noindentskip The work described in \chapref{visual_hand} and \ref{visuo_haptic_hand} was published in Transactions on Haptics:
 

5-conclusion/conclusion.tex

@@ -65,10 +65,10 @@ This only allowed us to estimate poses of the index finger and the surface to be
 In fact, preliminary tests we conducted showed that the built-in tracking capabilities of the HoloLens~2 were not able to track hands wearing a vibrotactile voice-coil device.
 A more robust hand pose estimation system would support wearing haptic devices on the hand as well as holding real objects.
 
-\comans{JG}{I [...] also want to highlight the opportunity to study the effect of visual registration error as noted already in chapter 4.}{Sentences along these lines has been added.}
-The spatial registration error \cite{grubert2018survey} and the temporal latency \cite{diluca2019perceptual} between the real and the virtual content should also be reduced to be imperceptible.
-The effect of these spatial and temporal errors on the perception and manipulation of the virtual content should be systematically investigated.
+The spatial registration error \cite{grubert2018survey} and the temporal latency \cite{diluca2019perceptual} between the \RE and \VE should also be reduced to be imperceptible.
+The effect of these spatial and temporal errors on the perception and manipulation of the virtual object should be systematically investigated.
 Prediction of hand movements should also be considered to overcome such issues \cite{klein2020predicting,gamage2021predictable}.
+\comans{JG}{I [...] also want to highlight the opportunity to study the effect of visual registration error as noted already in chapter 4.}{Sentences along these lines has been added.}
 
 A complementary solution would be to embed tracking sensors in the wearable haptic devices, such as an inertial measurement unit (IMU) or cameras \cite{preechayasomboon2021haplets}.
 This would allow a complete portable and wearable visuo-haptic system to be used in practical applications.
@@ -101,33 +101,47 @@ The dynamic response of the finger should also be considered, and may vary betwe
 As in the previous chapter, our aim was not to accurately reproduce real textures, but to alter the perception of a real surface being touched with simultaneous visual and haptic texture augmentations.
 However, the results also have some limitations, as they addressed a small set of visuo-haptic textures that augmented the perception of smooth and white real surfaces.
 Visuo-haptic texture augmentation might be difficult on surfaces that already have strong visual or haptic patterns \cite{asano2012vibrotactile}, or on objects with complex shapes.
-The role of visuo-haptic texture augmentation should also be evaluated in more complex tasks, such as object recognition and assembly, or in more concrete use cases, such as displaying and touching a museum object or a 3D printed object before it is manufactured.
+A real surface could be indeed augmented not only to add visuo-haptic textures, but also to amplify, diminish, mask, or replace the existing real texture.
+\comans{SJ}{It would be valuable to explore how real texture from a physical surface could be combined with virtual texture, enabling merged, augmented, amplified, or diminished feedback}{This has been better discussed.}
+In addition, the visual textures used were simple color images not intended for use in an \ThreeD \VE, and enhancing their visual quality could improve the perception of visuo-haptic texture augmentation.
 \comans{JG}{As future work, the effect of visual quality of the rendered textures on texture perception could also be of interest.}{A sentence along these lines has been added.}
-Finally, the visual textures used were simple color images not intended for use in an \ThreeD \VE, and enhancing their visual quality could improve the perception of visuo-haptic texture augmentation.
+It would also be interesting to replicate the experiment in more controlled visuo-haptic environments, in \VR or with world-grounded haptic devices.
+This would enable to better understand how the rendering quality, spatial registration and latency of virtual textures can affect their perception.
+\comans{SJ}{Moreover, if we only consider the experimental findings, the system could likely be recreated using VR or conventional visuo-haptic setups in a more stable manner. It would be beneficial to emphasize how the experiment is closely tied to the specific domain of haptic AR.}{This has been added.}
+Finally, the role of visuo-haptic texture augmentation should also be evaluated in more complex tasks, such as object recognition and assembly, or in more concrete use cases, such as displaying and touching a museum object or a 3D printed object before it is manufactured.
 
 \paragraph{Specificities of Direct Touch.}
 
-The haptic textures used were recordings and models of the vibrations of a hand-held probe sliding over real surfaces.
+The haptic textures used were recordings and models of the vibrations of a hand-held probe sliding over real surfaces \cite{culbertson2014one}.
 We generated the vibrotactile textures from velocity magnitude of the finger, but the perceived roughness of real textures also depends on other factors such as the contact force, angle, posture or surface of the contact \cite{schafer2017transfer}.
 The respective importance of these factors on the haptic texture perception is not yet fully understood \cite{richardson2022learning}.
 It would be interesting to determine the importance of these factors on the perceived realism of virtual vibrotactile textures in the context of bare finger touch.
 Finger based captures of real textures should also be considered \cite{balasubramanian2024sens3}.
 Finally, the virtual texture models should also be adaptable to individual sensitivities \cite{malvezzi2021design,young2020compensating}.
+\comans{SJ}{Technical concern: As far as I know, the texture rendering algorithm from [Curbertson et al.] is based on rigid-tool-based interactions. The vibration patterns due to texture in a bare-hand interaction scenario (used in this study) should differ significantly from those produced in rigid-tool interactions. I conduct similar research and am confident that the signals involved in bare-hand interactions are far more complex than those in rigid-tool-based interactions. Therefore, the choice of rendering algorithm could negatively affect the experimental results. This issue is critical and should either be revised or extensively discussed in the thesis.}{This has been discussed more in depth in this section.}
 
 \subsection*{Visual Augmentation of the Hand for Manipulating virtual objects in AR}
 
-\paragraph{AR Displays.}
+\paragraph{Other AR Displays.}
 
 The visual hand augmentations we evaluated were displayed on the Microsoft HoloLens~2, which is a common \OST-\AR headset \cite{hertel2021taxonomy}.
 We purposely chose this type of display, because in \OST-\AR the lack of mutual occlusion between the hand and the virtual object is the most challenging to solve \cite{macedo2023occlusion}.
 We therefore hypothesized that a visual hand augmentation would be more beneficial to users with this type of display.
 However, the user's visual perception and experience are different with other types of displays, such as \VST-\AR, where the \RE view is seen through cameras and screens (\secref[related_work]{ar_displays}).
-While the mutual occlusion problem and the hand pose estimation latency could be overcome with \VST-\AR, the visual hand augmentation could still be beneficial to users as it provides depth cues and feedback on the hand tracking, and should be evaluated as such.
+In particular, the mutual occlusion problem and the latency of hand pose estimation  could be overcome with a \VST-\AR headset.
+In this case, the occlusion rendering could be the most natural, realistic and effective augmentation.
+Yet, a visual hand augmentation could still be beneficial to users by providing depth cues and feedback on hand tracking, and should be evaluated as such.
+\comans{SJ}{According to the results, occlusion is the most natural (in terms of realism) but least efficient for manipulation. In some cases, natural visualization is necessary. It would be beneficial to discuss these cases to help guide AR interaction designers in choosing the most appropriate visualization methods.}{This has been discussed more in depth in this section.}
 
 \paragraph{More Practical Usages.}
 
 We conducted the user study with two manipulation tasks that involved placing a virtual cube in a target volume, either by pushing it on a table or by grasping and lifting it.
-These tasks are indeed fundamental building blocks for more complex manipulation tasks \cite[p.390]{laviolajr20173d}, such as stacking or assembly, which should also be considered. %, more ecological applications should be considered.
+These tasks are indeed fundamental building blocks for more complex manipulation tasks \cite[p.390]{laviolajr20173d} such as stacking or assembling, which should be investigated as well.
+They can indeed require users to perform more complex finger movements and interactions with the virtual object.
+Depending on the task, the importance of position, orientation and depth information of the hand and the object may vary and affect the choice of visual hand augmentation.
+More practical applications should also be considered, such as medical, educational or industrial scenarios, which may have different needs and constraints (\eg, the most natural visual hand augmentation for a medical application, or the easiest to understand and use for an educational context).
+\comans{SJ}{The task in the experiment is too basic, making it difficult to generalize the results. There are scenarios where depth information may be more important than position, or where positioning may be more critical than orientation. A systematic categorization and analysis of such cases would add depth to the chapter.}{This has been discussed more in depth in this section.}
+
 Similarly, a broader experimental study might shed light on the role of gender and age, as our subject pool was not sufficiently diverse in this regard.
 Finally, all visual hand augmentations received low and high rank rates from different participants, suggesting that users should be able to choose and personalize some aspects of the visual hand augmentation according to their preferences or needs, and this should also be evaluated.
 

5-conclusion/résumé.tex

@@ -108,7 +108,7 @@ Cependant, cette méthode n'a pas encore été intégrée avec un visiocasque de
   \subfig{vhar-system-apparatus-fr}
 \end{subfigs}
 
-Nous proposons un \textbf{système de rendu de textures virtuelles visuelles et haptiques}, portables et immersives, qui augmentent les surfaces réelles.
+Nous proposons un \textbf{système de rendu de textures virtuelles visuelles et haptiques} qui augmentent les surfaces réelles.
 Pour cela, nous utilisons le casque de réalité augmentée immersif Microsoft HoloLens~2 et un dispositif vibrotactile portable porté sur la phalange médiane (\figref{vhar-system-device-fr}).
 Les augmentations visuo-haptiques peuvent être \textbf{visualisées sous n'importe quel angle} et \textbf{explorées librement avec le doigt}, comme s'il s'agissait de textures réelles.
 
@@ -228,7 +228,7 @@ Nos résultats montrent qu'une augmentation visuelle de la main a amélioré les
 Le rendu sous forme de squelette, qui fournit une vue détaillée des articulations et des phalanges suivies, mais sans cacher la main réelle, s'est avéré le plus performant et le plus efficace.
 Le rendu des contours et le rendu du modèle 3D ont partiellement masqué la main réelle, tandis que le rendu aux extrémités des doigts a reçu des avis partagés.
 Le rendu d'occultation avait une latence perçue de suivi de la main trop importante pour être efficace et compris par les participants.
-Ces résultats sont cohérents avec ceux d'études antérieures sur la RV et les RA non immersives.
+Ces résultats sont cohérents avec ceux d'études antérieures en RA et RV.
 
 Cette étude suggère qu'une augmentation visuelle de la main en 3D est importante pour interagir avec une technique de main virtuelle en RA.
 Cela semble particulièrement requis lorsque l'utilisateur doit effectuer des mouvements précis avec ses doigts sur le contenu virtuel, comme avec des fenêtres 3D, des boutons ou des curseurs, ou encore lors de tâches plus complexes, telles que l'empilage ou l'assemblage d'objets virtuels.
@@ -278,7 +278,7 @@ Les dispositifs haptiques portables sont capables de fournir un retour tactile a
 Cependant, leur intégration avec la RA reste encore récente et présente de nombreux défis conceptuels, techniques et d'expérience utilisateur.
 Nous avons structuré cette thèse autour de deux axes de recherche~: \textbf{(I) modifier la perception visuo-haptique de la texture des surfaces réelles} et \textbf{(II) améliorer la manipulation des objets virtuels}.
 
-\noindentskip Nous nous sommes tout d'abord intéressés à la perception de texture visuo-haptique virtuelles portables et immersives qui augmentent des surfaces réelles (\secref{perception}).
+\noindentskip Nous nous sommes tout d'abord intéressés à la perception de texture visuo-haptique virtuelles portables qui augmentent des surfaces réelles (\secref{perception}).
 La texture est une propriété fondamentale d'un objet, perçue aussi bien par la vue que par le toucher.
 C'est également l'une des augmentations haptiques les plus étudiées, mais elle n'avait pas encore été intégrée à des contextes de toucher direct en RA ou RV.
 

config/content.tex

@@ -1,7 +1,7 @@
 % Changes
 \usepackage[commentmarkup=footnote]{changes}
 \definechangesauthor[name=Jens Grubert, color=Dandelion]{JG}
-\definechangesauthor[name=Seokhee Jeon, color=Red]{SG}
+\definechangesauthor[name=Seokhee Jeon, color=Red]{SJ}
 \newcommand{\comans}[3]{%
   \comment[id=#1]{%
     #2\\%

normand2025thesis.tex

@@ -32,7 +32,8 @@
 
 \frontmatter
 \import{0-front}{cover}
-%\listofchanges
+\pdfbookmark[chapter]{List of changes}{changes}
+\listofchanges
 %\importchapter{0-front}{acknowledgement}
 \importchapter{0-front}{contents}