SLARToolkit Samples Updated

The samples of my open source Windows Phone and Silverlight Augmented Reality Toolkit were updated to the latest version of the WP 7.1 and Silverlight 5 SDKs.
Please note the changed security model in Silverlight 5, which is a big bummer. My Silverlight MVP friend Morten wrote a few true words about it here.
As usual you can find a list of the samples on the project site and also get the code there.

Cubelicious - Silverlight 5 + Balder + Physics + SLARToolkit Augmented Reality = Triple Win!

Two months ago I released a new Silverlight 5 sample for my open source Silverlight Augmented Reality Toolkit - SLARToolkit. It uses the new Silverlight 5 hardware accelerated 3D API. You can read more about the new Silverlight 5 XNA 3D API in this blog post.
This post here provides a new demo for SLARToolkit which uses the open source 3D engine Balder by my friend Einar Ingebrigsten. This demo also leverages the open source physics engine JigLibX my buddy Andy Beaulieu ported over to Silverlight. You can try the live sample if you have the Silverlight 5 beta installed or watch a video instead.

I actually spent most of the time on this project a couple of weeks ago. My good Silverlight MVP friend Einar Ingebrigtsen used it in his talk at The Gathering 2011. Now I finally had a bit time to finish the demo, make a video and this blog post.

The SLARToolkit project description from the CodePlex site:

SLARToolkit is a flexible Augmented Reality library for Silverlight with the aim to make real time Augmented Reality applications with Silverlight as easy and fast as possible. It can be used with Silverlight's Webcam API or with any other CaptureSource or a WriteableBitmap. SLARTookit is based on the established NyARToolkit and ARToolkit. 

Live

A webcam and at least the Silverlight 5 beta runtime must be installed to run the sample. It's available here. Alternatively there is also a video of the new sample embedded below.

If you want to try it yourself you need do download the SLAR and / or L marker, print them and hold them in front of the camera. The marker(s) should be printed non-scaled at the original size (80 x 80 mm) and centered for a small white border. As an alternative it's also possible to open a marker file on a mobile device and to use the device's screen as marker. Also make sure the camera is set up properly and the scene is illuminated well without hard shadows. See the SLARToolkit Markers documentation for more details.

Open the sample in a new page.

Simply press the "Start Cam" Button to start the webcam. The properties of the particle system can  be changed with Sliders. The "Flip x-axis" Checkbox can be used to flip the video (the webcam output is mirror-reversed by default). 

If you click the "Start Cam" Button for the first time you need to give your permission for the capturing. This application uses the default Silverlight capture device. You can specify the video and audio devices that are used by default with the Silverlight Configuration. Just press the right mouse button over the application, click "Silverlight" in the context menu and select the "Webcam / Mic" tab to set them.

Video

I've recorded a short video of the new sample with Expression Encoder's Screen Capture feature. Please keep in mind that the screen recording software eats up a lot of resources while recording and that the actual frame rate is even better. The video is also available at YouTube.

Background music is Lullaby by _ghost

This demo shows how the new Silverlight 5 3D API, the Balder engine and the JigLibX physics library can be used to augment the reality with the help of SLARToolkit.

How it works

This sample uses the webcam video stream which fills a Rectangle shape, the video stream is also constantly captured and fed to the SLARToolkit BitmapMarkerDetector to detect the markers. The detection result contains a transformation matrix for each found marker which is then used to apply a global transformation to the cubes and the plane.
I implemented a particle system with a flexible directed emitter which can be controlled through various properties. The particle system is quite generic and can be used for all kinds of particles (3D objects). The particle collision detection and resolving is based on rigid body physics that was implemented with the help of the JigLibX library my Silverlight MVP buddy Andy Beaulieu ported over to Silverlight.
The rendering and the model loading is done by the 3D engine Balder. It's a fantastic open source engine by Einar Ingebrigtsen. You just need to write a couple lines of XAML and you're good to go. This sample only uses a simple cube model, but Balder has built-in model loaders to load complex 3D models and Einar provides a big sample library. He also brought the engine to a few more platforms like Windows Phone 7, OpenGL and has even a neat software rendering fallback. Read his blog post here.
As part of this sample I needed some vector and quaternion methods which were missing in Balder. I contributed those and the generic particle system to the Balder project. Feel free to use the particle system and the other methods in your Balder projects.

Download it, build your app and augment your reality

The open source SLARToolkit library and all samples are hosted at CodePlex. If you have any comments, questions or suggestions don't hesitate and write a comment, use the Issue Tracker on the CodePlex site or contact me via any other media.
Have fun with the library and please keep me updated if you use it anywhere so I can put a link on the project site.

Unity 3D and Silverlight in Harmony with SLARToolkit's Augmented Reality

If you read this blog regularly, you might have noticed a lot of SLARToolkit posts recently. But I'm not the only one using the open source Silverlight Augmented Reality Toolkit. There's great stuff happening out there and I see quite a few projects, especially in the academic field. You can find a full list of projects (I know of) on the SLARToolkit project site at CodePlex.
I love when people use my open source work, adapt or learn from it. This is what open source is all about for me.



One project recently caught my attention in particular. Ioulian Alexeev made a very amazing action game using the Unity 3D game engine and he combined it with SLARToolkit to control the spaceship with a marker. Ioulian studies Multimedia at the Arteveldehogeschool in Belgium and the game "StarFighter" was his bachelors test.

He recorded this nice video.

Note how he compares the performance of the Flash Augmented Reality Tookit and SLARToolkit:

Performance FLARManager: Not good enough for action games
Performance SLARToolkit: Very fast and accurate marker tracking

Both toolkits use the same marker-based AR algorithms from the ARToolkit.

Live
You can play the game here. If you want to try it yourself you need do download the SLAR and / or L marker, print them and point the camera toward these. The marker(s) should be printed non-scaled at the original size (80 x 80 mm) and centered for a small white border. As an alternative it's also possible to open a marker file on a different device and to use the device's screen as marker.
See the SLARToolkit Markers documentation for more details.

Augmented Mango - SLARToolkit for Windows Phone

The beta of the new Windows Phone Developer Tools was just publicly released. The update with the codename "Mango" comes with many new APIs and will finally contain an API for real-time camera access what a lot of developers have been asking for. The new runtime gives us the needed functionality to implement many cool scenarios. One of these scenarios is Augmented Reality, which leads to my open source Silverlight Augmented Reality Toolkit (SLARToolkit).
This post announces the new Windows Phone version of SLARToolkit and also provides a sample. If you're one of those lucky people with a Mango-enabled device you can download the XAP here or just watch a video instead.

The SLARToolkit project description from the CodePlex site:

SLARToolkit is a flexible marker-based Augmented Reality library for Silverlight and Windows Phone with the aim to make real time Augmented Reality applications with Silverlight as easy and fast as possible. It can be used with Silverlight's Webcam API or with any other CaptureSource, WriteableBitmap or with the Windows Phone's PhotoCamera. SLARTookit is based on the established NyARToolkit and ARToolkit. 

Demo

The sample XAP can be deployed to a Mango-enabled device (tested with build 7629). Alternatively there's also a video of the new sample embedded below.

If you want to try it yourself you need do download the SLAR and / or L marker, print them and point the camera toward these. The marker(s) should be printed non-scaled at the original size (80 x 80 mm) and centered for a small white border. As an alternative it's also possible to open a marker file on a different device and to use the device's screen as marker.
See the SLARToolkit Markers documentation for more details.

Video

I've recorded a short video of the new sample with my Samsung Omnia 7. It's a bit blurry, but it demonstrates how well the sample works even on this quite old ASUS prototype, which's camera pipeline seems a bit slow.
The video is also available at YouTube.

Background music is Melo by Mosaik

This demo shows how the new Windows Phone Mango real-time camera API can be used  to augment the reality with the help of the SLARToolkit. This can be nice for educational projects and it's actually no problem to add correctly transformed videos or other content to the demo.
The demo demonstrates just some basic UIElements like a TextBox and an Image control. Mango will also enable the combination of Silverlight and XNA, which means that nice 3D AR games can be developed with the help of the SLARToolkit. 

How it works

This sample uses the new PhotoCamera and a timer to constantly get a snapshot of the real-time camera stream. This snapshot is then passed to the SLARToolkit algorithms to get the 3D spatial information of the marker. The computed detection results are used to transform the elements perspectively correct.

protected override void OnNavigatedTo(System.Windows.Navigation.NavigationEventArgs e)
{
   base.OnNavigatedTo(e);

   // Initialize the webcam
   photoCamera = new PhotoCamera();
   photoCamera.Initialized += PhotoCameraInitialized;
   isInitialized = false;

   // Fill the Viewport Rectangle with the VideoBrush
   var vidBrush = new VideoBrush();
   vidBrush.SetSource(photoCamera);
   Viewport.Fill = vidBrush;

   // Start timer
   dispatcherTimer = new DispatcherTimer { Interval = TimeSpan.FromMilliseconds(50) };
   dispatcherTimer.Tick += (sender, e1) => Detect();
   dispatcherTimer.Start();
}

The PhotoCamera instance is set up in the OnNavigatedTo event handler of the page and the DispatcherTimer is started. The timer will constantly call the Detect method every 50 milliseconds. Additionally a viewfinder Rectangle is filled with a VideoBrush which in turn has the photoCamera video stream set as source.

void Detect()
{
   if (!isInitialized)
   {
      return;
   }

   // Update buffer size
   var pixelWidth = photoCamera.PreviewBufferResolution.Width;
   var pixelHeight = photoCamera.PreviewBufferResolution.Height;
   if (buffer == null || buffer.Length != pixelWidth * pixelHeight)
   {
      buffer = new byte[pixelWidth * pixelHeight];
   }

   // Grab snapshot
   photoCamera.GetPreviewBufferY(buffer);

   // Detect
   var dr = arDetector.DetectAllMarkers(buffer, pixelWidth, pixelHeight);

   // Calculate the projection matrix
   if (dr.HasResults)
   {
      // Center at origin of the 256x256 controls
      var centerAtOrigin = Matrix3DFactory.CreateTranslation(-128, -128, 0);
            
      // Swap the y-axis and scale down by half
      var scale = Matrix3DFactory.CreateScale(0.5, -0.5, 0.5);

      // Calculate the complete transformation matrix based on the first detection result
      var world = centerAtOrigin * scale * dr[0].Transformation;

      // Viewport transformation
      var viewport = Matrix3DFactory.CreateViewportTransformation(pixelWidth, pixelHeight);

      // Calculate the final transformation matrix by using the camera projection matrix 
      var m = Matrix3DFactory.CreateViewportProjection(world, Matrix3D.Identity, arDetector.Projection, viewport);

      // Apply the final transformation matrix to the controls
      var matrix3DProjection = new Matrix3DProjection { ProjectionMatrix = m };
      Txt.Projection = matrix3DProjection;
      Img.Projection = matrix3DProjection;
   }
}

A snapshot of the current preview buffer is taken in the Detect method using the GetPreviewBufferY method. This method fills up a byte buffer with the luminance data of the current viewfinder frame. This buffer is then passed to the SLARToolkit's MarkerDetector Detect method, which returns the detected marker information. This transformation data is then used to transform the UIElement perspectively correct in 3D.
Read more about the PhotoCamera's YCbCr methods in this blog post.

void PhotoCameraInitialized(object sender, CameraOperationCompletedEventArgs e)
{
   //  Initialize the Detector
   arDetector = new GrayBufferMarkerDetector();

   // Load the marker pattern. It has 16x16 segments and a width of 80 millimeters
   var marker = Marker.LoadFromResource("data/Marker_SLAR_16x16segments_80width.pat", 16, 16, 80);

   // The perspective projection has the near plane at 1 and the far plane at 4000
   arDetector.Initialize(photoCamera.PreviewBufferResolution.Width, photoCamera.PreviewBufferResolution.Height, 1, 4000, marker);

   isInitialized = true;
}

The SLARToolkit's GrayBufferMarkerDetector is created and set up in the PhotoCamera's Initialized event handler. The brand new GrayBufferMarkerDetector uses the byte buffer with luminance data directly without the need of an ARGB 32 bit pixel conversion.

Checkout the source code at CodePlex if you want to see all the details of the sample which were left out for clarity.

Download it, build your app and augment your reality

The open source SLARToolkit library and all samples are hosted at CodePlex. If you have any comments, questions or suggestions don't hesitate and write a comment, use the Issue Tracker on the CodePlex site or contact me via any other media.

Have fun with the library and please keep me updated if you use it anywhere so I can put a link on the project site.

Silverlight 5 3D + SLARToolkit Augmented Reality = Win!

It's almost been a year since I wrote a sample for my open source Silverlight Augmented Reality Toolkit - SLARToolkit. The release of the new Silverlight 5 hardware accelerated 3D API was a nice occasion to finally make a new one.
In my last blog post I wrote a summary of all the Silverlight 5 beta features and some notes about the new low-level, XNA 3D API.
This post provides the new demo for SLARToolkit which leverages this fast GPU-based rendering to draw some nice effects with 60 frames per second. You can try the live sample if you have the Silverlight 5 beta installed or watch a video instead.

The SLARToolkit project description from the CodePlex site:

SLARToolkit is a flexible Augmented Reality library for Silverlight with the aim to make real time Augmented Reality applications with Silverlight as easy and fast as possible. It can be used with Silverlight's Webcam API or with any other CaptureSource or a WriteableBitmap. SLARTookit is based on the established NyARToolkit and ARToolkit. 

Live

A webcam and at least the Silverlight 5 beta runtime must be installed to run the sample. It's available here. Alternatively there is also a video of the new sample embedded below.

If you want to try it yourself you need do download the SLAR and / or L marker, print them and hold them in front of the camera. The marker(s) should be printed non-scaled at the original size (80 x 80 mm) and centered for a small white border. As an alternative it's also possible to open a marker file on a mobile device and to use the device's screen as marker. Also make sure the camera is set up properly and the scene is illuminated well without hard shadows. See the SLARToolkit Markers documentation for more details.

Open the sample in a new page.

Simply press the "Start Fun" Button to start the webcam. The size of the objects can be changed with the "Scale" Sliders. The "Flip x-axis" Checkbox could be used to flip the video (the webcam output is mirror-reversed by default). Click the "Glass" Checkbox to apply a glass effect to the sun model.

If you click the "Start Fun" Button for the first time you need to give your permission for the capturing. This application uses the default Silverlight capture device. You can specify the video and audio devices that are used by default with the Silverlight Configuration. Just press the right mouse button over the application, click "Silverlight" in the context menu and select the "Webcam / Mic" tab to set them.

Video

I've recorded a short video of the new sample with Expression Encoder's Screen Capture feature. Please keep in mind that the screen recording software eats up a lot of resources while recording and that the actual frame rate is even better. The video is also available at YouTube.

Background music is Neon Aurora by Alpha C

This demo shows how the new Silverlight 5 3D API can be used  to augment the reality with the help of SLARToolkit. It also demonstrates how the 3D DrawingSurface can be combined with the webcam video stream and overlaid with ordinary TextBoxes. This can be nice for educational projects and it's actually no problem to add correctly transformed videos or other content to the demo.

How it works

This sample uses the webcam video stream which is used to fill a Rectangle shape, the video stream is also constantly captured and fed to the SLARToolkit BitmapMarkerDetector to detect the markers. The detection result contains a transformation matrix for each found marker which is then used to transform the 3D objects and the TextBoxes.
A couple of vertex and pixel shaders are used to get the desired effects. Techniques like Phong shading, Bump mapping and Refraction mapping (glass) were implemented. The snapshots from the webcam are passed as a texture to the refraction pixel shader to simulate the glass effect.
See the source code if you're interested in the nitty-gritty details. Please note that I wrote an introduction to Pixel Shaders for Coding4Fun a while ago.
The current Silverlight 5 beta doesn't implement RenderTargets, therefore effects like bloom aren't really possible with the limitations of the Shader Model 2. You can add a faded billboard around the sun, but it wouldn't look that nice and when RenderTargets are added we can do way more nice effects in future releases of Silverlight 5.
I also added a new simple anti-jittering functionality to SLARToolkit to prevent the jiggling that mostly occurred due to the varying lightning conditions and noise in the video stream.

Credits
The SolarWind sample by the Silverlight team was used as a base and extended. The sample uses earth textures from the NASA. The pixel shader for the sun uses textures and concepts from an article by Nicolas Menzel. The moon textures are from the Celestia project.

Download it, build your app and augment your reality

The open source SLARToolkit library and all samples are hosted at CodePlex. If you have any comments, questions or suggestions don't hesitate and write a comment, use the Issue Tracker on the CodePlex site or contact me via any other media.
Have fun with the library and please keep me updated if you use it anywhere so I can put a link on the project site.

Interview on .Net Rocks!

About a month ago Richard Campbell asked me if I'd like to give an interview about SLARToolkit on the .Net Rocks talk show. Of course I agreed right away. .Net Rocks! is the largest .Net developer podcast out there and Carl Franklin and Richard Campbell always have great guests. It's a real honor for me to have been on show #564.
We mainly talked about the Silverlight Augmented Reality Toolkit (SLARToolkit), but also about some of my other projects and articles.
You can download the podcast in various formats from here. I hope you like it. Also make sure you subscribe to .Net Rocks!

SLARToolkit Beginner's Guide

Since I released SLARToolkit I often get similar, basic questions. This is a sign that the SLARToolkit documentation and the samples might be too complex for a beginner. That's why I wrote an easy step by step Beginner's Guide which hopefully closes the gap. The tutorial shows how to build the simplest Silverlight Augmented Reality application possible.

The guide is part of the SLARToolkit documentation at CodePlex. Please read the Beginner's Guide here and let me know your feedback so I can improve it further.

SLARToolkit - Silverlight Augmented Reality Toolkit

In my last blog post I've preannounced SLARToolkit: The open source Silverlight Augmented Reality Toolkit. Today I'm proud to announce that SLARToolkit is now available at CodePlex.
The aim of SLARToolkit is to make Augmented Reality with Silverlight as easy as possible so that everyone will be able to make Silverlight Augmented Reality applications. Therefore the SLARToolkit release not only includes the full Balder sample you might know from this blog post, it also comes with a brand new sample that uses Silverlight's 3D projection capabilities through my Matrix3DEx library to project different UIElements on the marker.

The SLARToolkit project description from the CodePlex site:

SLARToolkit is a flexible Augmented Reality library for Silverlight with the aim to make real time Augmented Reality applications with Silverlight as easy and fast as possible. It can be used with Silverlight's Webcam API or with any other CaptureSource or a WriteableBitmap. SLARTookit is based on the established NyARToolkit and ARToolkit. SLARToolkit uses a dual license model and could be used for open or closed source applications under certain conditions. See the License page for details.

Features:

• Direct Support for Silverlight's CaptureSource
• Flexible through a generic WriteableBitmap detector
• Multiple marker detection
• Simple black square markers
• Custom markers
• Real time performance
• Easy to use
• Documentation
• Based on established algorithms and techniques
• Uses the Matrix3DEx library

Live
A webcam and at least the Silverlight 4 runtime must be installed to run the sample. It's available for Windows and Mac. Alternatively there is also a new video of the Silverlight projection sample embedded below.
If you want to try it yourself you need do download the SLAR and / or L marker, print them and hold them in front of the camera. The marker(s) should be printed non-scaled at the original size (80 x 80 mm) and centered for a small white border. Also make sure the camera is set up properly and the scene is illuminated well without hard shadows. See the SLARToolkit Markers documentation for more details.

Open the sample in a new page.

Simply press the "Start Fun" Button to start the webcam. Use the ComboBox to select a different UIElement that will be mapped on the marker. The size and the orientation can be changed with the "Scale" and "Rotation" Sliders. The "Threshold" Slider controls the threshold for the marker detection. The "Flip x-axis" Checkbox could be used to flip the video (the webcam output is mirror-reversed by default).
If you click the "Start Fun" Button for the first time you need to give your permission for the capturing. This application uses the default Silverlight capture device. You can specify the video and audio devices that are used by default with the Silverlight Configuration. Just press the right mouse button over the application, click "Silverlight" in the context menu and select the "Webcam / Mic" tab to set them.

Video
I've recorded a short video of the new sample with Expression Encoder's Screen Capture feature. Please keep in mind that the screen recording software eats up a lot of resources while recording and that the actual frame rate is way better.

Background music is leandi by mosaik.

How it works
This sample uses the SLARToolkit CaptureSourceMarkerDetector to detect the markers in each webcam frame. The detection result contains a transformation matrix for each found marker which is then used to transform the selected UIElement. The tracked marker region is highlighted with a red quad through the WriteableBitmapEx library.

Download it, build your app and augment your reality

The open source SLARToolkit library and the samples are hosted at CodePlex. If you have any comments, questions or suggestions don't hesitate and write a comment, use the Issue Tracker on the CodePlex site or contact me via any other media.
Have fun with the library and please keep me updated if you use it anywhere so I can put a link on the project site.

Update 03-15-2010
Updated to the Silverlight 4 Release Candidate.

Update 04-15-2010
Updated to the final Silverlight 4 RTW build.

SLARToolkit Preannouncement

SLARToolkit has been released. Please read this blog post.

In my latest blog posts, the comments and on Twitter I hinted at on one of the projects I'm currently working on: SLARToolkit - The Silverlight Augmented Reality Toolkit. My aim for SLARToolkit is to make Augmented Reality with Silverlight as easy as possible, fast and open source. With this everyone will be able to make Silverlight Augmented Reality applications like that one. SLARToolkit is based on NyARToolkit which is a extented port of the famous ARToolkit. I'm almost done with the implementation and in contact with ARToolworks, which are holding the license for ARToolkit, to get a license agreement. I hope I'll be able to release SLARToolkit within the next two or three weeks at CodePlex. Please stay tuned.


Two weeks ago Julien Dollon contacted me and asked if I could help him with an Augmented Reality demo for his Silverlight 4 talk at Microsoft TechDays 2010 in Paris. Since I'm a nice guy, I've built a special SLARToolkit version for him and send it along with the source code of the SLARToolkit Silverlight projection sample. The sample uses my Matrix3DEx library to project UIElements on the markers. Actually the Matrix3DEx library has its roots there.
Julien altered the sample a bit and showed it at MS TechDays 2010 during his Silverlight 4 talk last week. The presentation was recorded and the official video is available, but you can also watch Julien's self recorded video of the session. The SLARToolkit demo starts at 39:02.

And the official screen cast:

World# - Real Time 3D Augmented Reality with Silverlight

Please read the Update at the end of this post.

In the Silverlight 4 Augmented Reality Proof Of Concept blog post I proved that it's possible to implement Augmented Reality applications with Silverlight 4 and the built-in webcam API. The proof of concept used an image showing a Silverlight logo that was attached to the tracked marker. With this blog post I'm back in this field, but this time with real 3D Augmented Reality in Silverlight!
I use the open source Augmented Reality library NyARToolkitCS again and implemented the necessary interfaces to make it work with Silverlight. The NyARToolkitCS library is a completely managed version of the well known ARToolkit. I also use the open source managed game engine Balder for the rendering of 3D models that augment the reality. Balder is mainly developed by the Silverlight MVP Einar Ingebrigtsen. He is working hard on his 3D game engine and provided quick fixes for some issues I encountered while using Balder and I also had a nice chat with him, so big shout out to Einar.

Live
A webcam and at least the Silverlight 4 runtime must be installed to run the sample. To view the application you need to install the Silverlight 4 runtime. It's available for Windows and Mac. You can also watch a video below.
If you want to try it yourself you need do download the SLAR and / or L marker, print them and hold them in front of the camera. The marker(s) should be printed non-scaled at the original size (80 x 80 mm) and centered for a small white border. Also make sure the camera is set up properly and the scene is illuminated well without hard shadows. See the SLARToolkit Markers documentation for more details.

Try it out here.

Simply press the "Start Fun" Button, hold the printed marker in front of the camera and move it around. Use the ComboBox to select a different 3D model. The "Flip x-axis" Checkbox could be used to flip the video (the webcam output is mirror-reversed by default).
If you click the "Start Fun" Button for the first time you need to give your permission for the capturing. This application uses the default Silverlight capture device. You can specify the video and audio devices that are used by default with the Silverlight Configuration. Just press the right mouse button over the application, click "Silverlight" in the context menu and select the "Webcam / Mic" tab to set them.
The Car model was made by Psionic, the Tank model by Ken Beyer. The Teapot is from the Balder samples and I guess it was made by Einar Ingebrigtsen. The rest was made by myself.

Video
This time I used Expression Encoder's Screen Capture feature to record a short video of the demo in action. Please keep in mind that the screen recording software eats up a lot of resources while recording and that the actual frame rate is way better.

Background music is Black Lipstick by 4mat / ATEbit (Matt Simmonds).

How it works
Every time the CompositionTarget.Rendering event is fired, a webcam snapshot is taken asynchronously with the CaptureSource.AsyncCaptureImage method. This snapshot is converted in the right format and passed to the NyARToolkitCS library that outputs a transformation matrix. This matrix is used to transform the 3D model. The Balder viewport has a transparent background and the scene with the 3D objects is laid over the webcam video output. Another layer is an image that uses a WriteableBitmap and the WriteableBitmapEx library to highlight the tracked marker region with a red quad.
Sounds pretty easy, but actually it was not that easy and straight forward. One of the hardest parts was the initialization and to find the right parameters.

Results
I'm quite satisfied with the results and if you consider that all the heavy computation is done by the CPU, the performance is pretty good as well. The demo runs smoothly at 50-60 fps on a dual core machine utilizing its whole power and it should also scale up on more cores.

To be continued
If you expected source code this time I have to disappoint you. The code is not at that level where it should be, but I wanted to push this demo out. I'm not sure if I find enough time this year to work on the code and I don't want that someone tries to use it in the current state. But trust me, I will provide open source functionality to make Augmented Reality in Silverlight in the near future and I normally keep my promises, so stay tuned for more happy days...

Update 02-24-2010
This demo is now part of the open source SLARToolkit library which was announced in this blog post.

Update 03-15-2010
Updated to the Silverlight 4 Release Candidate.

Update 04-15-2010
Updated to the final Silverlight 4 RTW build.