Team Assignment 0: Intro to Augmented Reality DUE: 9-29
Contents
1. Step 2 Now open Tutorials sIn in GoblinXNAv3 4 tutorials Right click on tutorial 8 and Set As Startup Project Make sure useStaticImage is false set this to false if you are going to use a webcam bool useStaticImage false Make sure your capture parameters are set to 60 FPS at 640x480 in the SetupMarkerTracking method else captureDevice new DirectShowCapture captureDevice InitVideoCapture 0 FrameRate 60Hz Resolution 640x480 ImageFormat R8G8B8 24 false 7 Step3 Hit the green arrow Now you should see some a cube and a sphere if you point your camera at the ground marker Step 4 Play around with the ground and the toolbar markers and get a feel for moving them around at different speeds and from different distances from the camera Try moving the camera around with the objects stationary Cover parts of the ground marker up and see if you can get it to disrupt the tracking Part Ill Create a new marker for use in AR Step 1 Go to the command line Start gt Run gt cmd Navigate to the folder where you unzipped camcalibandmarkers zip Step 2 Type samplemarkercreator 0 and press enter Step 3 If you look in the directory now you should see MarkerData_0 png Open it Notice that this is also one of the markers on one of the corners of the ground array It would confuse the tracking system to have two of these markers in the same scene We need to generate a new marker NOTE the ground array f2. Make sure the settings are set as follows Properties Video Proc Amp Camera Control Brightness Contrast 32 Saturation 28 Sharpness 191 White Balance 6600 a Backlight Comp 0 Auo E Se Make sure auto is unchecked everywhere The other parameters you may have to adjust these depending on the lighting AR works better in a well lit area like the computer labs U Properties Video Proc Amp Camera Control Exposure gt oO Pan You want to keep the exposure as low as you can without the image becoming too dark If you increase exposure time you will see that the image appears to slow down and blur at times This makes tracking more error prone You may have to adjust this based on the lighting Don t try to use the Brightness parameter to compensate for poor lighting It will just make tracking worse Step 5 Hit Apply to save settings and then hit OK Close AMCap Step 6 Download camcalibandmarkers zip and unzip it somewhere Step 7 Open Alvar pdf Print out page 9 make sure to choose None for page scaling Lay the checkerboard on a flat surface You want this to be as flat as possible Tape may help Step 8 Open CameraCalibration exe and point the camera at the checkerboard You should see some numbers print out like Sample Image 1 Each time you see these numbers print it means that it has successfully taken a screenshot that will be used for calibration If it can t see the
3. an array You must adjust the xml file for this as with any other marker array design 2 There should always be white space around each individual marker There is no answer as to how much but too little could confuse the tracking if the camera is far enough away 3 For best results your markers must be as flat as possible Pasting them on a rigid surface like cardboard is very helpful Part IV Importing your marker into Goblin XNA Step 1 Open Tutorials sin in GoblinXNAv3 4 tutorials Step 2 Right click on Tutorial8 Optical Marker Tracking in the Solution Explorer and click Add gt Existing Item Change Objects of type to Navigate to ALVARConfigFromXML txt in your GoblinXNAv3 4 tutorials Tutorial8 Optical Marker Tracking folder Select it and click Add Step 3 You should now see ALVARConfigFromXML txt just under Content in the properties window Right click on it and select Properties You should now see the properties window for it Step 4 Under Copy to Directory select Copy if newer Part V Track your marker and display a cylinder Step 1 Add MarkerNode cylinderMarkerNode to the instance fields near the top of Tutorial8 cs You will see other MarkerNodes there Step 2 At the end of CreateObjects add ids new int 4 ids 0 50 ids 1 51 ids 2 52 ids 3 53 cylinderMarkerNode new MarkerNode scene MarkerTracker ALVARConfigFromXML txt ids Step 3
4. Remember the sequence of ids you used for your marker array If not look back at your SampleLayout xml file Replace the ids above with your ids Step 4 Below that create a cylinder and add it to the scene graph as follows GeometryNode cylinderNode new GeometryNode Cylinder cylinderNode Model new Cylinder 3 3 6 10 cylinderNode Material sphereMaterial TransformNode cylinderTransNode new TransformNode cylinderTransNode Translation new Vector3 0 0 3 cylinderMarkerNode AddChild cylinderTransNode cylinderTransNode AddChild cylinderNode scene RootNode AddChild cylinderMarkerNode In general you create a GeometryNode for the cylinder model and a TransformNode to define the position orientation scale You then add the TransformNode as a child to the MarkerNode and the GeometryNode as a child to the TransformNode Then the MarkerNode is made a child of the scene root node Notice how translated it up by its radius so it looks flush against the marker Step 5 Hit the green arrow and play with your new AR cylinder Take a screenshot and save it as newmarker jpg Part VI What are the main limitations of AR Step 1 Write a list of 5 ways to break the illusion disrupt tracking etc Step 2 Describe two of the tracking errors that you saw and explain in detail how to how to reproduce them 4 5 sentences Submit Step 1 Zip the screenshot Part V Step 5 and the text file from part VI Make sure a
5. Team Assignment 0 Intro to Augmented Reality DUE 9 29 11 11 59PM IF THE PICTURES IN THIS PAGE DON T WORK USE THE PDF Required Preliminary Reading GoblinXNA user manual the section on Augmented Reality starting on page 32 Work with your final project team Overview In this assignment you will learn basic skills to implement Augmented Reality AR in GoblinXNA and become familiar with the associated tools for camera calibration and paper marker generation The leaning objectives are the following 1 Understand how to set up an AR environment in GoblinXNA 2 Understand how to create new AR interfaces with paper markers 3 Most important Understand the affordances and limitations of AR as a user interface Background AR Game Example Racing Game in GoblinXNA Part I Calibrating your camera Step 1 Plug in your camera Step 2 Open AMCap from a lab computer desktop or download it yourself and open it Step 3 You should now see the captured video from your camera Go to Options gt Video Capture Pin Set it for YUV2 640x480 and 30 FPS You will set the camera to run at 60 FPS in your programs but AMCap does not allow this Hit OK Properties Stream Format Video Format Compression Video Standard None Frame Rate 30 000 Frame Interval P Frame Interval Color Space Compression Yuy2 Output Size Quality fs 640 x 480 v Step 4 Go to Options gt Video Capture Filter
6. checkerboard or you are at too close an angle to the checkerboard plane it won t take a picture until you move the camera to a better position Hold the page perpendicularly facing your camera It doesn t have to be perfectly aligned just try to get all of the black and white squares into the picture When it gets to 50 images it will put the results into calib xml in the same directory Close the CameraCalibration windows NOTE if for some reason CameraCalibration doesn t work for you recompile it like this http goblinxna codeplex com wikipage title Calibrating 20the 20Camera amp referringTitle Doc umentation Note calib xml is the calibration file for your specific camera You should not have to do this calibration again if you don t lose your calib xml By showing the camera this checkerboard of known dimensions the software calculated the unique camera parameters like lens distortion and focal length Step 9 Now copy calib xml into the GoblinXNAv3 4 tutorials Tutorial8 Optical Marker Tracking folder Part Il Try out AR in GoblinXNA Step 1 In GoblinXNAv3 6 tutorials Tutorial8 Optical Marker Tracking you will find groundALVAR pdf and toolbarALVAR pdf Print these out with page scaling set to none You will need a longer sheet of paper for the groundALVAR pdf Actually it will still work if choose Shrink to Printable Area but later GoblinXNA might think the camera is further away from the marker than it actually is
7. ll of your team member s names are in the text file Step 2 Submit through blackboard It doesn t matter who submits You will all get credit
8. rom tutorial 8 is not special You could just remove it from the code and then reuse those markers on it in a different marker array Currently it uses marker ids 0 27 Step 4 Choose 4 numbers in sequence e g 50 51 52 53 between 54 and 65535 Try to keep your numbers as low as you can since GoblinXNA does not support many of the higher ones e g 65535 For each number type samplemarkercreator yournumber into the command line and press enter You should now see a MarkerData_yournumber png for each of the 4 your numbers Step 5 Open the SampleLayout xml from the same directory Visual Studio works well to edit XML Edit the XML image parameters to point to your marker png files instead of the markers included Change the id parameters to match Take note of the size in inches of your marker array width pixelPerInch height pixelPerInch In this case it is 8in x 8 in Save the changes Step 6 Run MarkerLayout exe This should generate ALVARArrayFromxXML gif and ALVARConfigFromXML txt Copy ALVARConfigFromXML txt into your GoblinXNAv3 6 tutorials Tutorial8 Optical Marker Tracking folder Step 7 Open Microsoft Word or some other layout program GIMP works for this too but is more complicated and insert the ALVARArrayFromXML gif into the document Right click on the inserted image and click Size Change it to the correct size you computed in Step 5 8in x 8in Step 8 Optional Widen the margins of the document and center the marker S
9. tep 9 Print out the marker making sure not to rescale anything SampleLayout xml Explained Here are the main points you need to know about the XML file width height this is the size in pixels of the image produced Keep in mind that each marker is 108x108 pixels So if you wanted to put four markers in a column width would need to be GREATER THAN 108 4 You need to keep some white border around the individual markers This is necessary for tracking pixelPerInch this defines the actual size that the marker array should be when printed out At width 400 height 400 and pixelPerInch 50 the resulting gif should be printed out to be 8in x 8in center this is the origin of the coordinate system of the marker When you attach a model to the marker in GoblinXNA this is the position where the object will be drawn by default you can change this in GoblinXNA with a TransformNode that has the MarkerNode as a parent If you set the center to be width 2 height 2 as have done in the example the origin will be at the center of the marker upperLeftCorner this defines where an individual marker appears within the resulting image Marker Design Tips for Good Tracking Performance You will have to design new marker arrays for your final project 1 Multiple markers in an array are typically better than a single marker However depending on the constraints of your design you might want to have one marker rather than four in
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