Introduction to VR principle explanation and development

This article is written by the author Obuil based on many years of experience for the VR developers who want to get started, supported by the 52VR website.   1. The principle of VR immersion and interaction: before, we watched a virtual creation content is through the flat screen display, 52VR last published an article "A picture let you know VR", in which you will see a lot of 10 years ago virtual reality equipment, they are basically flat screen display, Or the resulting picture is projected onto an arc or even a spherical screen, or the screen is overlaid with images of the left and right eye, resulting in a more stereoscopic effect. This type of device is often large and expensive.  in recent years, the development of the VR head wear display, it has achieved better use effect: better immersion and cheaper prices, the current set of mainstream VR glasses is less than 10,000 yuan.  What is the principle of this kind of VR glasses that can achieve a better sense of immersion?

we see that VR glasses, mainly through three aspects to achieve the purpose of immersion: 

1) through the convex lens to enlarge the human eye to see the real-time image range, now the VR glasses will probably produce a 90-120-degree range of image vision, such a vision and a good three-channel ring-screen projection system produces almost the same effect, but VR glasses to more close to the human eye, The likelihood of the human eye being disturbed is greatly reduced.

2) through the head of the gyroscope, when the person turns the head, the gyroscope can timely inform the image generation engine, timely update the screen, so that people feel that they are looking at a surrounding virtual space, resulting in 360 degrees of three-dimensional sense of space.

3) The right and left eye every moment to see the image is not the same, is two different from the left and right eye position of the various heads, resulting in a very strong sense of stereoscopic depth. The above three reasons are the immersion characteristics of VR glasses.

  2. Definition of immersion and interaction for the definition of these two nouns, I think it might be possible to explain: 1) The so-called immersion feeling users in a four-dimensional virtual world, the user of various sensory organs, especially the visual organs of the virtual world of adaptive positive feedback.  

In terms of the current VR glasses, mainly through two aspects to achieve the purpose of immersion:

1. One is through the enlarged display technology, can display a magnified local virtual time scene in front of the user, at present the field of view angle is about 90-110 degrees, in this display range, mainly through three-dimensional engine technology, produce real-time stereoscopic image.
2. The second is through and the head of the position of the sensor data matching, so that the three-dimensional engine response to the head rotation direction (and the current head position changes) to a very high frequency real-time change the display of the three-dimensional picture, the user head rotation angle just and three-dimensional engine simulation three-dimensional picture vision consistent, let the user feel that the In the observation of a virtual three-dimensional world.

  2) The so-called interaction The user is able to communicate effectively with the virtual world through actions, gestures, language and other human natural ways. generally speaking, the user's hands, feet walking, in the virtual world to create a user can understand the change, the user thinks that the virtual world to the user feedback, then the user's action and the virtual world to the user's feedback, combined together to form an interactive role    so the theme came, to achieve the current VR glasses immersive interactive effect, it is necessary to have a complete set of software and content cooperation.   3. How to generate virtual worlds that meet VR requirements 

To generate a three-dimensional virtual world, since the three-dimensional game was born, there is no lack of tools, it can be considered that all three-dimensional construction and rendering capabilities of the graphics engine, can generate three-dimensional virtual image of the world, many engines have a complete game engine function, not limited to the image, but also produce sound, Simulations of physical phenomena such as those currently present in the world include but are not limited to:

 1) Top 10 of the world's most well-known engines, including engines produced by major gaming companies

1. The Dead engine, the American EA Company re-made engines
2. Avalanche Engine,
3. Mt framework engine, Ghost cry game Do you know? That's what this is about.
4. Anvil engine, Ubsoft's engine
5. Ego engine
6. Cold Frost Engine
7. CryEngine
8. IW engine
9. Naughty Dog engine
10. Unreal Engine

 2) There is also a bunch of open source rendering engines, interested students can download down to try:OGRE, Irrlicht, Panda3D, Crystal Space, JME, Blender Game Engine, Reality Factory, the Nebula Device 2, Realmforge, OpenSceneGraph What is an engine: 

These engines are based on the computer operating system API and graphics driver interface built to facilitate the rapid production of high-level application developers of content, between the engine and the operating system, in fact, there is generally a layer of middleware, basic graphics interface:

On WINDOWSPC and mobile operating systems, it is the DirectX base image API

In industry, on Linux, Apple PC and iphone, on the Android operating system, is a series of OpenGL basic graphics interface (mobile side is OpenGL ES, is a simplified OpenGL version)

 almost all engines are built on either or both of these.     4. The most mainstream VR development engine because of its difficulty, function perfect, development cost and other reasons, the engine is the most popular and suitable for the development of VR content after a long period of rise and fall process:  

Unity	Unreal Engine	CryEngine
no open source easy to get started multiplatform development Easy    	The current unreal fourth-generation version of've seen is still the no.! of the engine. Its features are briefly summed up as: Open source The software system is complete and does not require additional plugins. visual presentation and functionality are extremely powerful Getting Started is not easy	The best of the island engine, its masterpiece in effect, most people think more powerful than unreal, its characteristics are summarized as follows: Open source editor powerful Getting Started difficult
More than three: more plugins, more resources, more documents	Many documents	Not many documents

The above engine comparison, you can see my other article: "Current VR game development, using unity or Unreal4?" What are the three types of engines that support VR? these three engines have built-in support for VR to varying degrees 

Unity	Unreal Engine	CryEngine
Built-in STEAMVR plug-in Built-in OSVR plug-in	built-in STEAMVR plug-in built-in OSVR plug-in	Built-in OSVR plug-in

with the STEAMVR and Osvr plug-in native support provided by the above engine, developers can use plug-ins to create virtual reality experiences that are compatible with different devices without worrying about the evolution of feature APIs and devices themselves in VR glasses.  What is the STEAMVR plugin? SteamVR is a VR game platform for Value Inc., and its open source SDK is the OPENVR,OPENVR SDK, which is updated by the original Steamworks SDK, which contains support and encapsulation for several VR devices, This allows developers to face the interface of the OPENVR SDK without having to face a specific device interface, which includes support for the HTC Vive and Oculus Rift developer versions, as well as steam VR controllers and location devices. The relevant APIs are implemented in C + +, and developers who already have C + + experience can learn directly.  What is the Osvr plugin? the snake and its partners created a virtual reality open platform: OSVR Open Source VR system (Open-source virtual Reality). OSVR is designed to support software plug-ins (Unity 3D, Unreal Engine 4 and Hero Engine (heroengine), input hardware (sixsense and leap Motion, etc.) and other virtual reality devices, including Oculus Rift DK2 and Vrvana Totem.   with the above mainstream engine and dedicated VR plugin, then you can open, come to 52vr.com together to learn these mainstream production tools, we will continue to launch the following links: 1) Introduction to Unity VR development2) Introduction to VR development of Unreal Engine3) Introduction to CryEngine VR development

Introduction to VR principle explanation and development