#import "../chapter.typ"

#chapter.chapter(count: false)[Introduction]

During the last years, 3D acquisition and modeling techniques have made tremendous progress.
Recent software uses 2D images from cameras to reconstruct 3D data, e.g.
#link("https://alicevision.org/\#meshroom")[Meshroom] is a free and open source software which got almost 200.000 downloads on #link("https://www.fosshub.com/Meshroom.html")[fosshub], which use _structure-from-motion_ and _multi-view-stereo_ to infer a 3D model.
More and more devices are specifically built to harvest 3D data: for example, LIDAR (Light Detection And Ranging) can compute 3D distances by measuring time of flight of light. The recent research interest for autonomous vehicles allowed more companies to develop cheaper LIDARs, which increase the potential for new 3D content creation.
Thanks to these techniques, more and more 3D data become available.
These models have potential for multiple purposes, for example, they can be printed, which can reduce the production cost of some pieces of hardware or enable the creation of new objects, but most uses are based on visualization.
For example, they can be used for augmented reality, to provide user with feedback that can be useful to help worker
with complex tasks, but also for fashion (for example, #link("https://www.fittingbox.com")[Fittingbox] is a company that develops software to virtually try glasses, as in @fittingbox).

#v(50pt)
#figure(
  image("../assets/introduction/fittingbox.png", width: 45%),
  caption: [My face with augmented glasses]
)<fittingbox>

#pagebreak()

3D acquisition and visualization is also useful to preserve cultural heritage, and software such as Google Heritage or 3DHop are such examples, or to allow users navigating in a city (as in Google Earth or Google Maps in 3D).
#link("https://sketchfab.com")[Sketchfab] (see @sketchfab) is an example of a website allowing users to share their 3D models and visualize models from other users.

#figure(
  image("../assets/introduction/sketchfab.png", width: 100%),
  caption: [Sketchfab interface]
)<sketchfab>

In most 3D visualization systems, the 3D data are stored on a server and need to be transmitted to a terminal before the user can visualize them.
The improvements in the acquisition setups we described lead to an increasing quality of the 3D models, thus an increasing size in bytes as well.
Simply downloading 3D content and waiting until it is fully downloaded to let the user visualize it is no longer a satisfactory solution, so adaptive streaming is needed.
In this thesis, we propose a full framework for navigation and streaming of large 3D scenes, such as districts or whole cities.

#pagebreak()

#include("challenges.typ")
#include("outline.typ")
