Figure 1.
Process flow of the proposed foveated DoF technique showing the intermediate outputs. Fixation is at the center of the red sphere.
Figure 1.
Process flow of the proposed foveated DoF technique showing the intermediate outputs. Fixation is at the center of the red sphere.
Figure 2.
Illustration of the circle of confusion concept. Point of fixation is at distance . Point located at distance forms a circle on the retina with diameter C. A denotes the aperture and s is the posterior nodal distance.
Figure 2.
Illustration of the circle of confusion concept. Point of fixation is at distance . Point located at distance forms a circle on the retina with diameter C. A denotes the aperture and s is the posterior nodal distance.
Figure 3.
An example scene along with its associated depth map.
Figure 3.
An example scene along with its associated depth map.
Figure 4.
Depth-of-field effects for different planes of fixation. Points of fixation (depth values are reported in red on the images) are on the vase and the front tree in the left and right images, respectively.
Figure 4.
Depth-of-field effects for different planes of fixation. Points of fixation (depth values are reported in red on the images) are on the vase and the front tree in the left and right images, respectively.
Figure 5.
Human field-of-view for both eyes showing the foveal, near, mid, and far peripheral regions.
Figure 5.
Human field-of-view for both eyes showing the foveal, near, mid, and far peripheral regions.
Figure 6.
Stereoscopic view of the multi-region foveation output. The central region has no blur applied while the other two regions (highlighted in green for sake of visualization only) have different blurs applied to them.
Figure 6.
Stereoscopic view of the multi-region foveation output. The central region has no blur applied while the other two regions (highlighted in green for sake of visualization only) have different blurs applied to them.
Figure 7.
Example of an output from the foveated depth-of-field blur filter.
Figure 7.
Example of an output from the foveated depth-of-field blur filter.
Figure 8.
Rollercoaster track outline. The arrow indicates the direction of motion. The coordinate system follows the convention used in Unity, i.e., X: right direction; Y: up direction; Z: forward direction.
Figure 8.
Rollercoaster track outline. The arrow indicates the direction of motion. The coordinate system follows the convention used in Unity, i.e., X: right direction; Y: up direction; Z: forward direction.
Figure 9.
Instantaneous user velocity and acceleration components during each rollercoaster cycle. The coordinate system follows the convention used in Unity, i.e., X: right direction; Y: up direction; Z: forward direction. Seesaw motion: 8–32 s; spiral motion: 36–44 s and 48–64 s.
Figure 9.
Instantaneous user velocity and acceleration components during each rollercoaster cycle. The coordinate system follows the convention used in Unity, i.e., X: right direction; Y: up direction; Z: forward direction. Seesaw motion: 8–32 s; spiral motion: 36–44 s and 48–64 s.
Figure 10.
Rollercoaster virtual environment. (A) user-view; (B) rollercoaster cart with VR camera attached; (C) top view of the clustered environment.
Figure 10.
Rollercoaster virtual environment. (A) user-view; (B) rollercoaster cart with VR camera attached; (C) top view of the clustered environment.
Figure 11.
SSQ scores for the cybersickness experiment (conditions: NB—No Blur; GC—Unity Blur; FD—Ours). The questionnaire was filled before (Pre) and after (Post) each session. Each plot shows the mean values, averaged over all the participants, and the standard deviations for the three sub-scales and the overall score.
Figure 11.
SSQ scores for the cybersickness experiment (conditions: NB—No Blur; GC—Unity Blur; FD—Ours). The questionnaire was filled before (Pre) and after (Post) each session. Each plot shows the mean values, averaged over all the participants, and the standard deviations for the three sub-scales and the overall score.
Figure 12.
Comparison of the Post-Pre difference of the SSQ scores for each condition (conditions: NB—No Blur; GC—Unity Blur; FD—Ours). The plot shows the changes in individual SSQ scores between the pre and post experiment conditions.
Figure 12.
Comparison of the Post-Pre difference of the SSQ scores for each condition (conditions: NB—No Blur; GC—Unity Blur; FD—Ours). The plot shows the changes in individual SSQ scores between the pre and post experiment conditions.
Figure 13.
IPQ scores for the cybersickness experiment (conditions: NB—No Blur; GC—Unity Blur; FD—Ours). The questionnaire was filled after each session. NB: Involvement 3.57, Experienced Realism 4.07, Spatial Presence 5.09; GC: Involvement 3.60, Experienced Realism 3.57, Spatial Presence 4.90; FD: Involvement 3.83, Experienced Realism 4.53, Spatial Presence 5.21.
Figure 13.
IPQ scores for the cybersickness experiment (conditions: NB—No Blur; GC—Unity Blur; FD—Ours). The questionnaire was filled after each session. NB: Involvement 3.57, Experienced Realism 4.07, Spatial Presence 5.09; GC: Involvement 3.60, Experienced Realism 3.57, Spatial Presence 4.90; FD: Involvement 3.83, Experienced Realism 4.53, Spatial Presence 5.21.
Figure 14.
Average heart rate fluctuations from a resting heart rate during a rollercoaster cycle. Origin on the heart rate axis represents the resting heart rate. (conditions: NB—No Blur; GC—Unity Blur; FD—Ours).
Figure 14.
Average heart rate fluctuations from a resting heart rate during a rollercoaster cycle. Origin on the heart rate axis represents the resting heart rate. (conditions: NB—No Blur; GC—Unity Blur; FD—Ours).
Figure 15.
Heatmap of the visual field for user gaze combined for all sessions performed. The circles are centered at the center of the HMD screen and indicate the visual angle (e.g., the 10° circle represents the central 20° of visual eccentricity). The colors represent how frequent the user fixated at that particular location on the HMD screen with white representing 0 and black representing 9358.
Figure 15.
Heatmap of the visual field for user gaze combined for all sessions performed. The circles are centered at the center of the HMD screen and indicate the visual angle (e.g., the 10° circle represents the central 20° of visual eccentricity). The colors represent how frequent the user fixated at that particular location on the HMD screen with white representing 0 and black representing 9358.
Figure 16.
Histogram for angular speed greater than 350°/s of the eye for all users during a saccade.
Figure 16.
Histogram for angular speed greater than 350°/s of the eye for all users during a saccade.
Figure 17.
Comparison of the Post–Pre difference of the SSQ scores for each condition with respect to age groups (conditions: NB—No Blur; GC—Unity Blur; FD—Ours). The plot shows the changes in individual SSQ total scores between the Pre and Post experiment conditions for the two age groups. Old: NB 68.34, GC 47.55, FD 22.26; Young: NB 55.03, GC 37.06, FD 19.38.
Figure 17.
Comparison of the Post–Pre difference of the SSQ scores for each condition with respect to age groups (conditions: NB—No Blur; GC—Unity Blur; FD—Ours). The plot shows the changes in individual SSQ total scores between the Pre and Post experiment conditions for the two age groups. Old: NB 68.34, GC 47.55, FD 22.26; Young: NB 55.03, GC 37.06, FD 19.38.
Figure 18.
Comparison of the Post–Pre difference of the SSQ scores for each condition with respect to gender groups (conditions: NB—No Blur; GC—Unity Blur; FD—Ours). The plot shows the changes in individual SSQ total scores between the Pre and Post experiment conditions for the two age groups. Male: NB 60.67, GC 44.37, FD 21.63; Female: NB 59.84, GC 46.72, FD 19.39.
Figure 18.
Comparison of the Post–Pre difference of the SSQ scores for each condition with respect to gender groups (conditions: NB—No Blur; GC—Unity Blur; FD—Ours). The plot shows the changes in individual SSQ total scores between the Pre and Post experiment conditions for the two age groups. Male: NB 60.67, GC 44.37, FD 21.63; Female: NB 59.84, GC 46.72, FD 19.39.
Table 1.
The Wilcoxon rank sum test confidence scores between Pre and Post states for the different subcategories of the SSQ test (N—Nausea; O—Oculomotor; D—Disorientation; TS—Total Score); (conditions: NB—No Blur; GC—Unity Blur; FD—Ours).
Table 1.
The Wilcoxon rank sum test confidence scores between Pre and Post states for the different subcategories of the SSQ test (N—Nausea; O—Oculomotor; D—Disorientation; TS—Total Score); (conditions: NB—No Blur; GC—Unity Blur; FD—Ours).
| N | O | D | TS |
---|
NB | p = 0.001 | p = 0.002 | p = 0.002 | p = 0.001 |
GC | p = 0.001 | p = 0.003 | p = 0.004 | p = 0.001 |
FD | p = 0.005 | p = 0.004 | p = 0.004 | p = 0.003 |
Table 2.
The mean, standard deviation, and 95% confidence intervals of the Post-Pre difference of the SSQ scores for each condition (N—Nausea; O—Oculomotor; D—Disorientation; TS—Total Score); (conditions: NB—No Blur; GC—Unity Blur; FD—Ours).
Table 2.
The mean, standard deviation, and 95% confidence intervals of the Post-Pre difference of the SSQ scores for each condition (N—Nausea; O—Oculomotor; D—Disorientation; TS—Total Score); (conditions: NB—No Blur; GC—Unity Blur; FD—Ours).
| Mean (Standard Deviation) | 95% Confidence Interval |
---|
NB—N | 49.29 (5.81) | [43.14, 55.44] |
NB—O | 53.48 (6.56) | [46.27, 60.69] |
NB—D | 54.13 (7.83) | [46.08, 62.19] |
NB—TS | 60.26 (7.16) | [52.65, 67.85] |
GC—N | 30.74 (8.44) | [26.91, 34.57] |
GC—O | 39.58 (11.61) | [33.65, 45.52] |
GC—D | 46.40 (11.88) | [40.86, 51.94] |
GC—TS | 44.05 (11.14) | [38.92, 49.17] |
FD—N | 16.96 (9.07) | [12.97, 20.95] |
FD—O | 46.40 (5.09) | [10.56, 17.79] |
FD—D | 25.52 (10.56) | [21.05, 29.99] |
FD—TS | 20.51 (7.63) | [16.57, 24.42] |
Table 3.
Comparison among different techniques for reducing cybersickness. S is the reduction in the mean sickness scores between the no effect condition and the best performing condition/parameters.
Table 3.
Comparison among different techniques for reducing cybersickness. S is the reduction in the mean sickness scores between the no effect condition and the best performing condition/parameters.
Technique | HMD | VE/Task | ΔS |
---|
Dynamic FOV modification [19] | Oculus Rift DK2 | Reach waypoints | 5.6% |
Rotation blurring [22] | Oculus Rift DK2 | FPS shooter game | 17.9% |
Peripheral visual effects [23] | HTC Vive | Find objects | 49.1% |
FOV reduction (vignetting) [24] | HTC Vive | Follow butterfly | 30.1% |
Dynamic blurring (saliency) [25] | HTC Vive | Race track | 35.2% |
Static peripheral blur [43] | HTC Vive Pro | Maze | 54.8% |
Unity depth blur | HTC Vive Pro Eye | Rollercoaster | 26.9% |
Foveated DoF (ours) | HTC Vive Pro Eye | Rollercoaster | 66.0% |
Table 4.
Comparison of angular speed during saccadic motion for each user. Number of occurrences of speeds greater than 200°/s and the peak speed observed are shown. (conditions: NB—No Blur; GC—Unity Blur; FD—Ours).
Table 4.
Comparison of angular speed during saccadic motion for each user. Number of occurrences of speeds greater than 200°/s and the peak speed observed are shown. (conditions: NB—No Blur; GC—Unity Blur; FD—Ours).
User | NB | GC | FD |
---|
>200°/s | Peak | >200°/s | Peak | >200°/s | Peak |
---|
AT | 106 | 810°/s | 89 | 502°/s | 59 | 354°/s |
CT | 132 | 784°/s | 108 | 544°/s | 96 | 497°/s |
EV | 88 | 859°/s | 99 | 743°/s | 74 | 556°/s |
GB | 136 | 546°/s | 90 | 650°/s | 101 | 549°/s |
HR | 115 | 773°/s | 125 | 663°/s | 97 | 568°/s |
KK | 78 | 593°/s | 71 | 539°/s | 84 | 542°/s |
LH | 132 | 731°/s | 93 | 707°/s | 103 | 581°/s |
MB | 87 | 581°/s | 116 | 582°/s | 63 | 431°/s |
MM | 112 | 703°/s | 95 | 697°/s | 88 | 553°/s |
ND | 101 | 802°/s | 107 | 718°/s | 71 | 655°/s |
NR | 86 | 824°/s | 119 | 702°/s | 105 | 603°/s |
OQ | 88 | 595°/s | 92 | 629°/s | 95 | 612°/s |
SA | 106 | 697°/s | 105 | 735°/s | 94 | 514°/s |
SR | 97 | 710°/s | 82 | 657°/s | 68 | 570°/s |
TB | 113 | 688°/s | 89 | 617°/s | 87 | 545°/s |
UG | 115 | 591°/s | 84 | 623°/s | 89 | 511°/s |
US | 92 | 597°/s | 111 | 502°/s | 89 | 533°/s |
YK | 67 | 351°/s | 142 | 661°/s | 67 | 508°/s |
Total | 1999 | 859°/s | 1923 | 743°/s | 1619 | 655°/s |
Table 5.
Frame rate comparison (conditions: NB—No Blur; GC—Unity Blur; FD—Ours).
Table 5.
Frame rate comparison (conditions: NB—No Blur; GC—Unity Blur; FD—Ours).
System | Average Processing Time | 95% Confidence Interval | Frame Rate |
---|
NB | 15.9 ms | [15.9 ms, 15.9 ms] | 63 Hz |
GC | 17.2 ms | [17.1 ms, 17.3 ms] | 58 Hz |
FD | 16.7 ms | [16.6 ms, 16.8 ms] | 60 Hz |