Archives For Microsoft

My team at Microsoft shipped the high definition face tracking and face shape modelling tech as part of XBox One Kinect back in November 2013. These are some facial expressions that can be tracked by Kinect in real time and animated in 3D (gray masks) with pretty good precision:

HDFaceTrackingSamples

 

The system finds a big number of semantic points on a user’s face in 3D. The developers can then use this information to animate avatars or do some other processing (like recognize expressions, etc.). This video shows the early prototype of this technology that I made back in 2012:     This is a bit more technical video that demos the 3D mask painted over the video stream (for those who like this stuff):     The algorithm that we created is a fusion of a 2D video feature tracker based on Active Appearance Model (AAM) and a 3D tracker based on Iterative Closest Point (ICP) algorithm, which aligns 3D face model based on depth data from Kinect. Both trackers are resolved together and linked by special 2D-3D constraints such that the alignment makes sense and looks natural. We are going to publish details as a paper some time soon. We also compute 3D face shapes for a given user from a set of input frames (RGB + depth).

We published this paper that describes the face tracking and modeling algorithms in details. The resulting 3D models are pretty realistic and look like this:

 

OnlineShapeFit_Nikolai_April23_2013

 

Now it is up to game developers to use this tech in their titles! The API is available as part of Xbox One XDK. For example you can produce NPC faces like this in your game:

Nikolai as a textured shape model

Nikolai as a textured shape model

 

The 3D model that we shipped in Xbox One Kinect + face capture system is very capable and flexible. The face tracking and face shape modelling is used in just released Kinect Sports Rivals game by RARE studio. You can see the face shape modelling demo in this video:

 

 

    Microsoft just demoed a very cool game Kinectimals at E3 that uses Kinect – computer vision and natural UI system (formerly known as “Natal”). The game is for kids, but I think adults will enjoy it as well. See this video:

    Looks pretty awesome to me. But oddly enough, some online comments in some articles called it “creepy” or “scary” or people could not believe that Kinect/Natal actually works. Well, I know how to adress the last concern and Kinect does work. But, I wonder why some people think of virtual pets with AI and Kinect type interaction as “scary” or “creepy”… I am working on one project that might get similar response and I wonder if people are really that scared of AI and virtual worlds? May be older folks are scared, but kids are not? To me, it looks very exciting and awesome, but I am an engineer. We’ll see in November 2010 if Kinect becomes a hit. It probably will be a killer platform with killer games and it is very bad news for Sony and Nintendo, because it will be very very hard to replicate anything like this.

    Today, I saw the live broadcast of the demo of the new XBox interface (project “Natal”) at E3 conference. It stunned me! This is a groundbreaking event in the interface design and can be compared to the mouse invention (but it goes much much further). Microsoft did something revolutionary!

    This new interface is based on video cameras that watch your movements, calculate positioning of your body and then translate it to the movements of your avatar in a game. Also, it includes speech recognition, facial recognition and probably a set of other features. They demoed sport games where you control your avatar by literally moving in front of a TV and it does exactly what you do (kicks balls, move legs up and down, etc.). It is much better than Wii, since you actually don’t need any device/controller. Your body controls your avatar in the game.

    These demos were pretty impressive and showed that MS just outdid everyone else in this space (I think competition will have big problems catching up), BUT it got even better! Lionhead founder Peter Molyneux kicked off another demo where a woman was interacting with a virtual boy. It looked like a very real conversation where the virtual boy actually knew where the woman was and was talking to her and not to the space like in today’s games. At some point, the woman drew a picture and gave it to the boy (gave it to the front camera) and the boy took a virtual piece of paper with THIS picture on it! The other interesting thing was when the woman was making patterns on the water and you could see her reflected image on it. Oh yeah, and they were also talking in plain English. It seems like speech recognition also works really well.

Virtual boy Milo

Virtual boy Milo

project Natal in action

project Natal in action

As I posted earlier, my team at Microsoft (Windows Live Core) shipped the Tech Preview of the new online service – Live Mesh. I worked on the Account service that takes care of account management, and user/device authentication and authorization. There were many questions asked by early adopters about how their data is transmitted and stored in Live Mesh, and how access is controlled. In this post I’ll talk about Live Mesh security and authorization architecture, so that you understand its internals and feel better about trusting your data to the Mesh.

Here is the diagram that illustrates all communications between user devices and Live Mesh cloud services and encryption/security mechanisms used in these communication channels:

Live Mesh Security

Live Mesh security is rooted at the authentication provider (Windows Live ID, aka Microsoft Passport, is our provider today) which is used for initial user and device authentication. Once a user or a device is authenticated and a corresponding authentication token is obtained, the Live Mesh client passes this token to the Live Mesh Account service to access the root of the user’s mesh and to get the initial set of Live Mesh tickets. These tickets are used for further Mesh operations on other resources that this root is pointing to. All communications with the Live Mesh cloud services are done via HTTPS / SSL, so 3rd parties cannot intercept and read client-server communication.

All user (or device) related resources in Live Mesh are organized in a RESTful manner, i.e. they form a graph where each node is identified by a unique URL and represents a given resource. Nodes contain resource metadata and links to other resources. Mesh operations are essentially CRUD operations on the nodes of the user tree or nodes of other user trees if those users shared any data. Live Mesh cloud services check access rights in each operation by inspecting passed tickets and authorizing access only if a correct set of tickets is passed. Tickets can be obtained from the Account service or from responses to previous cloud operations.

Live Mesh authorization tickets are standard SAML tickets. They are digitally signed with the Live Mesh private key to prevent spoofing and they expire after a limited lifetime. Some tickets are used to just authenticate users or devices, other tickets contain authorization information about user/device rights. Cloud services inspect each resource request and authorize access only if it contains valid tickets (correctly signed and not expired) and these tickets specify that the requestor indeed has access to the requested resource. For example, a device X can initiate P2P data synchronization with device Y only if it presents a ticket that is correctly signed by Live Mesh and contains a record saying that both device X and Y are claimed by the same user OR if it contains a record saying that X and Y have the same Live Mesh Folder mapped on them (in the case that the devices are claimed by different users that are members of this Live Mesh Folder). Tickets are passed to the cloud services in the Authorization header using HTTPS to prevent replay attacks.

Each device in Live Mesh (computers, PDAs, mobile phones) has a unique private key that is generated during Live Mesh installation and used to authenticate the device in P2P communications with other devices. When a P2P communication is being established between two devices, they first use asymmetric encryption (RSA algorithm) to exchange encryption keys and then use symmetric encryption (AES with 128 bit key) to transfer data/files over TCP/IP. The RSA exchange guards against leaking symmetric encryption keys. AES encryption protects actual data from prying eyes. Live Mesh also uses a keyed message authentication code (HMAC) to verify the integrity of the data exchanged on a P2P channel.

If there is no direct connection between two devices (for example, if one device is behind a firewall), then the cloud communication relay located in the Microsoft data center is used to forward data packets from one device to another. All the traffic is encrypted in the same way as in the case with direct P2P link, i.e. first keys are exchanged with RSA and then traffic is encrypted with AES. The cloud relay cannot decrypt/read user data, since encryption keys are exchanged with the use of asymmetric encryption (RSA).

Live Mesh cloud services help devices find each other and establish communications. They cannot read synchronized user data/files relayed through the cloud, except for the case when user files are synchronized with the cloud storage (i.e. Live Desktop). At the moment, the limited Tech Preview of Live Mesh synchronizes your files not only between your devices, but also with your cloud storage (which you can access via Live Desktop) until you reach your storage quota (5GB as of today). So your files and metadata that describes them are stored in the Microsoft datacenter. They are protected by strong access control mechanisms, but the data is not stored in encrypted form. After the storage quota has been reached, all files are synchronized only P2P and not stored in the cloud (only metadata is stored in the datacenter). In the future, Live Mesh will allow users to selectively choose which files or Live Mesh Folders they want to synchronize with the cloud. If you choose to synchronize your data/files between your devices only, Live Mesh will not store your files in the cloud and will only store metadata that lets the service to operate.

UPDATE: Some of Live Mesh services were later integrated into Microsoft’s SkyDrive, but it’s been awhile since I worked there, I am not sure which parts of this article are valid in case of SkyDrive. Read it as a historical post if you wish 🙂

 

On April 22nd, my team at Microsoft (Windows Live Core) released a limited public beta of new online service – Live Mesh. Since then, I read several online reviews about it and got some feedback from people I invited into the system. I found one interesting common trait – not all users/reviewers actually use all of the present capabilities of the system. That’s why I decided to review its main user visible features and how I use it, so it may be helpful to people interested in Live Mesh. A more detailed discussion can be found here.

Live Mesh is a service that allows accessing your data and devices from anywhere. It consists of a set of cloud and client side services. Cloud services manage user accounts, help your devices to find each other and connect to each other, provide cloud storage for your files (5GB at the moment). Client side services synchronize data between your devices, between your devices and the cloud storage, and provide remote access to your devices. Also, Live Mesh is a platform and when its SDK is released it will help developers in creating distributed applications that use synchronized user data. Applications will just read/write from/to local data objects that will be automatically synchronized by the service in the background.

From the user experience perspective, Live Mesh is exposed at the moment as 3 main things: file synchronization between user devices (computers, PDAs, mobile phones), remote access to computers (aka “Live Remote Desktop“) and the web desktop (aka “Live Desktop“) where people can see their files stored in “the cloud”.

Here is the screenshot of my “Live Desktop” that I can access from any web browser. You can see my Live Mesh folders with files on the left. 2 folders are opened. One of the folders has a train picture rendered by the SilverLight viewer.

Live Desktop

Another opened folder has several subfolders and files. The companion window on its right shows news about activities in this folder, e.g. when stuff was added and messages from members of this folder (users that have access to it). On the right, you can see a pane window with my devices that are in my “Mesh”. I can remotely access these computers right from the web browser by clicking on “connect to device” links.

All people that I invited, started with their Live Desktops (it is the 1st feature users see when they sign up), but not all moved beyond it to the other 2 very interesting parts of Live Mesh – actual file sync and Live Remote. They are installed as part of the Live Mesh client (set of client side services), which is available via “Devices” button on your Live Desktop. This button leads to the famous device ring that by some reason all online reviews were focused on. If you click on “Add device” icon on the ring, you can get to the client setup.

After you install the client portion of Live Mesh and claim your computer on first sign in (claiming adds it to your Mesh of devices), the service starts synchronizing your files between the cloud, your other computers and this newly added computer. Here is the screenshot of my desktop with several Live Mesh Folders opened:

Desktop with Live Mesh Folders

At the top part of my desktop, you can see the same folders as in my Live Desktop. 4 of them in solid colors are “mapped” to this computer and are synchronized by Live Mesh. 2 of them are shown as ghosted and even though they are available in the cloud they are not synchronized to this device. I can start synchronizing them by just double clicking on them. The window on the upper left shows all Live Mesh folders that I created or a member of. The middle window is the opened Live Mesh folder with its members on its right (users that have access to it). I can invite more people to this folder by clicking on “members” tab and entering their LiveID. In this case, they will get an email with a link that points to Live Desktop where they can accept my invitation and provision their user account if they don’t have one. Once they join this folder and install the Live Mesh client, they can map this folder to their desktops and get all its files and file changes. I share photos with my family this way – once I make new photos I just drop them to one of the synchronized folders and my family members can see them once they are synchronized to their computers. It is much more convenient than publishing photos one by one on online sites, the viewing experience is better, since photos can be nicely rendered by the desktop software in original resolutions and I can argue that it is more secure and private. I think that Live Mesh client UX clearly demostrates the advantage of Rich Internet Applications over web applications (even if they are Web 2.0 apps like Live Desktop).

The pane window on the right is the Live Mesh client UI and shows all my devices where I installed the client. I can see their status (online/offline) or remotely access them. You can see that Live Desktop is just another device in my “Mesh”. If I click on one of my computers (“connect to device” link), Live Remote Desktop starts and I can actually work on this computer remotely. Here is the screenshot of Live Remote with my home computer in it:

Live Remote in Live Mesh

You can see the same Live Mesh Folders mapped on this remote computer (on the left), the train picture opened in the photo viewer, the opened Live Mesh folder and the Live Mesh client UI with my devices. I can work remotely on this computer as if I were there in front of it. If I drop a file into one of the Live Mesh folders, it will be automatically synchronized and appear on my other computers/devices where this folder is mapped to and in my Live Desktop. My home computer works behind NAT, but I can still access it. Live Mesh makes it possible to synchronize and remotely access computers even if they are behind firewalls, NATs, etc.

If I need to get my photos from my home computer while I am at work I can remote to it, drop them into one of the Live Mesh folders and after they are synchronized browse them on my work computer. Or when I go home and need to continue working on something, I can just drop relevant files into a Live Mesh folder and when I arrive home use them. No more flash drives or sending emails to myself 🙂 In addition to usual file synchronization, you can drag and drop files between your desktop and a Live Remote window or between 2 Live Remote windows. In this case, files will be just copied to a remote computer or to your current computer. Recently, I was quite surprised that I was able to remote to my home computer while I was riding a bus with a WiFi connection. File synchronization also worked fine (it was a bit slow though). So you can really get to your data and devices from anywhere with this service.