D.2 Rendered viewports
26.1183GPPRelease 17TSVirtual Reality (VR) profiles for streaming applications
Error! Reference source not found. illustrates an example of clustering and the associated viewports. The first three evaluated viewports are all with the distance D (indicated by the blue circle), and are thus assigned to the same cluster. Note that the cluster center moves a bit for each new viewport which is added to the cluster.
Viewport #4 is too far away from the center of cluster #1, and thus starts a new cluster, which eventually gathers three viewport members. Then viewport #7 is too far away from the center of cluster #2, and again starts a new cluster.
Figure D.2-1: Clustering example
For each cluster j, the final averaged viewport parameters can be derived as follows, assuming there are N viewports in the j:th cluster. Note that the center azimuth and tilt averaging also needs to handle the special case around -180/180 degrees, as some values might be positive (e.g. 176 degrees), while others might be negative (e.g. -178 degrees). This special case is not shown in the equations below.
Note also that the azimuth and elevation range (i.e. the visible coverage of the viewport) might often be the same for every viewport, unless the user explicitly changes the field-of-view for the device. For consistency, and to catch any during-session field-of-view changes, these two parameters should still be averaged.
Figure D.2-2 below illustrates an example of the duration filtering. The user starts by looking at the upper left part of the media (viewports #1 to #3), then make a very brief glance to the right (viewport #4), and then moves back to the upper-left again (viewports #5 and #6). Then the user moves his gaze to the lower-right part (viewports #7 to #10).
Assume here that the duration T is set to 4 times the value of the viewport sample rate X, i.e. a cluster needs to have a duration corresponding to at least four viewports to be reported. Here four clusters are formed, but before filtering only cluster #4 would be reported. After filtering, clusters #1 and #3 are close enough both in time and distance to add to each other’s aggregated duration, so each of them will be assigned an aggregated duration of 5, and thus be reported. Cluster #2, the quick glance up to the right, has too short duration and will not be reported.
Figure D.2-2 Duration filtering example
Annex E (informative):
Change history
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Change history |
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Date |
Meeting |
TDoc |
CR |
Rev |
Cat |
Subject/Comment |
New version |
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2018-06 |
SA#80 |
SP-180270 |
Presented to TSG SA#80 (for information) |
1.0.0 |
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2018-09 |
SA#81 |
SP-180647 |
Presented to TSG SA#81 (for approval) |
2.0.0 |
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2018-09 |
SA#81 |
Approved at TSG SA#81 |
15.0.0 |
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2018-12 |
SA#82 |
SP-180967 |
0001 |
2 |
F |
Corrections to 26.118 |
15.1.0 |
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2019-09 |
SA#85 |
SP-190649 |
0002 |
– |
F |
Correction of figure references |
15.2.0 |
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2020-03 |
SA#87-e |
SP-200038 |
0003 |
– |
B |
Addition of Feature |
16.0.0 |
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2020-03 |
SA#87-e |
Editorial Correction in Change History, Copyright etc |
16.0.1 |
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2020-03 |
Post SA#87-e |
Minor Editorial changes |
16.0.2 |
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2020-12 |
SA#90-e |
SP-200932 |
0005 |
A |
Corrections to Video Operation Points |
16.1.0 |
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2021-01 |
Post SA#90-e |
Update of History Table |
16.1.1 |
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2021-04 |
SA#91-e |
SP-210038 |
0006 |
4 |
B |
Operation Points for 8K VR 360 Video |
16.2.0 |
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2021-04 |
SA#91-e |
This version is identical to 16.1.1 and to be used as the latest Rel 16 version.CR0006r4 had to be implemented on 16.1.1 to build Rel 17 version (instead,16.2.0 has been inadvertently updated with CR0006r4 and hence this rollback was necessary). |
16.2.1 |
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2021-06 |
SA#92-e |
SP-210532 |
0009 |
F |
Spatial positioning of the chroma samples for VR Video Profiles |
16.3.0 |
|
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2021-06 |
SA#92-e |
SP-210534 |
0007 |
2 |
B |
Operation Points for 8K VR 360 Video |
17.0.0 |
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2021-06 |
SA#92-e |
SP-210534 |
0008 |
C |
Addition of HLG transfer characteristics |
17.0.0 |
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2021-06 |
SA#92-e |
SP-210533 |
0010 |
1 |
F |
Spatial positioning of the chroma samples for VR Video Profiles |
17.0.0 |