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Erwan Normand
2025-04-12 15:03:25 +02:00
parent b296d3ae98
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3-perception/xr-perception/3-experiment.tex
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@@ -14,9 +14,9 @@ In order not to influence the perception, as vision is an important source of in
The visual rendering stayed the same during the trial.
The pictures are captured directly from the Microsoft HoloLens 2 headset.
][
\item The real environment and real hand view without any visual augmentation.
\item The real environment and hand view with the virtual hand.
\item Virtual environment with the virtual hand.
\item The \RE with real hand view and without any visual augmentation.
\item The \RE with real hand and virtual hand view.
\item The \VE with the virtual hand.
]
\subfig[0.326]{experiment/real}
\subfig[0.326]{experiment/mixed}
@@ -31,13 +31,15 @@ It consisted of a \qtyproduct{30 x 21 x 40}{\cm} medium-density fibreboard box w
A single light source of \qty{800}{\lumen} placed \qty{70}{\cm} above the table fully illuminated the inside of the box.
Participants rated the roughness of the paper (without any texture augmentation) before the experiment on a 7-point Likert scale (1~=~Extremely smooth, 7~=~Extremely rough) as quite smooth (\mean{2.5}, \sd{1.3}).
The visual rendering of the virtual hand and environment was achieved using the \OST-\AR headset Microsoft HoloLens~2 (\secref[vhar_system]{virtual_real_alignment}) running at \qty{60}{FPS} a custom application made with Unity (v2021.1) and Mixed Reality Toolkit (v2.7).
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}).
The \VE carefully reproduced the \RE, including the geometry of the box, textures, lighting, and shadows (\figref{renderings}, \level{Virtual}).
\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}.
Its size was adjusted to match the real hand of the participants before the experiment.
The visual rendering of the virtual hand and environment is described in \secref[vhar_system]{virtual_real_alignment}.
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.
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.
@@ -63,7 +65,7 @@ The user study was held in a quiet room with no windows.
\label{procedure}
Participants were first given written instructions about the experimental setup and procedure, the informed consent form to sign, and a demographic questionnaire.
A calibration was then performed to adjust the HoloLens~2 to the participant's interpupillary distance (IPD), the virtual hand to the real hand size, and the fiducial marker to the finger position.
The calibration was then performed to adjust the HoloLens~2 to the participant's interpupillary distance, the fiducial marker to the finger position, and the virtual hand size to the real hand.
They familiarized themselves with the task by completing four training trials with the most different pair of textures.
The trials were divided into three blocks, one for each \factor{Visual Rendering} condition, with a break and questionnaire between each block.
Before each block, the experimenter ensured that the \VE and the virtual hand were correctly aligned with their real equivalents, that the haptic device was in place, and attached the cardboard mask corresponding to the next \factor{Visual Rendering} condition to the headset.