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Thomas Forgione
2019-10-18 11:12:24 +02:00
parent 197a7f6519
commit 0ccd968900
2 changed files with 122 additions and 49 deletions
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src/state-of-the-art/3d-streaming.tex
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@@ -66,6 +66,8 @@ After content preparation, the mesh consists in a base mesh and a sequence of pa
Thus, a client can start by downloading the base mesh, display it to the user, and keep downloading and displaying details as time goes by.
This process reduces the time a user has to wait before seeing something, and increases the quality of experience.
These methods have been vastly researched \citep{isenburg2006streaming,courbet2010streaming,bayazit20093,mamou2010shape}, but very few of these methods can handle meshes with attributes, such as texture coordinates.
\citep{streaming-compressed-webgl} develop a dedicated progressive compression algorithm for efficient decoding, in order to be usable on web clients.
With the same objective, \citep{pop-buffer} proposes pop buffer, a progressive compression method based on quantization that allows efficient decoding.
@@ -91,21 +93,14 @@ On the one hand, using segments containing very few faces will induce many HTTP
On the other hand, if segments contain too many faces, the time to load the segment will be long and the system loses adaptability.
This approach works well for several objects, but does not handle view-dependent streaming, which is desirable in the use case of large NVEs\@.
\subsection{Geometry and textures}
As discussed in Chapter~\ref{f:3d}, meshes consists in two main types of data: geometry and textures.
When addressing 3D streaming, one must find a compromise between geometry and textures, and a system needs to solve this compromise.
Balancing between streaming of geometry and texture data are considered by~\citep{batex3},~\citep{visual-quality-assessment}, and~\citep{mesh-texture-multiplexing}.
All three work considered a single, manifold textured mesh model with progressive meshes.
Their approach is to combine the distortion caused by having lower resolution meshes and textures into a single view independent metric.
\citep{progressive-compression-textured-meshes} also deals with the geometry / texture compromise.
This work designs a cost driven framework for 3D data compression, both in terms of geometry and textures.
This framework generates an atlas for textures that enables efficient compression and multiresolution scheme.
\subsection{Viewpoint dependency}
3D streaming means that content is downloaded while the user is interacting with the 3D object.
In terms of quality of experience, it is desirable that the downloaded content is visible to the user.
This means that the progressive compression must allow a decoder to choose what it needs to decode, and to guess what it needs to decode from the users point of view.
This is typically called \emph{random accessible mesh compression}.
\citep{maglo2013pomar} is such an example of random accessible progressive mesh compression.
In the case of large scene 3D streaming, viewpoint dependent streaming is a must-have: a user will only be seeing one small portion of the scene at each time, and a system that does not adapt its streaming to the user's point of view is bound to have poor quality of experience.
A simple way to implement viewpoint dependency is to access the content near the user's camera.
@@ -121,6 +116,23 @@ Even though there are no associated publications, it seems that the interface do
In the same vein, \citep{3d-tiles} developed 3D Tiles, is a specification for visualizing massive 3D geospatial data developed by Cesium and built on top of glTF\@.
Their main goal is to display 3D objects on top of regular maps.
\subsection{Geometry and textures}
As discussed in Chapter~\ref{f:3d}, meshes consists in two main types of data: geometry and textures.
When addressing 3D streaming, one must find a compromise between geometry and textures, and a system needs to solve this compromise.
Balancing between streaming of geometry and texture data are considered by~\citep{batex3},~\citep{visual-quality-assessment}, and~\citep{mesh-texture-multiplexing}.
All three work considered a single, manifold textured mesh model with progressive meshes.
Their approach is to combine the distortion caused by having lower resolution meshes and textures into a single view independent metric.
\citep{progressive-compression-textured-meshes} also deals with the geometry / texture compromise.
This work designs a cost driven framework for 3D data compression, both in terms of geometry and textures.
This framework generates an atlas for textures that enables efficient compression and multiresolution scheme.
\citep{simon2019streaming} propose a way to stream a set of textures by encoding the textures into a video.
Each texture is segmented into tiles of a fixed size.
Those tiles are then ordered to minimise dissimilarities between consecutive tiles, and encoded as a video.
By benefiting from the video compression techniques, they are able to reach a better rate-distortion ratio than webp, which is the new standard for texture transmission, and jpeg.
% \copied{}
% \subsection{Prefetching in NVE}
% The general prefetching problem can be described as follows: what are the data most likely to be accessed by the user in the near future, and in what order do we download the data?