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Augmented Reality Sandbox DIY

Here you will find all the information required to set up your own custom sandbox.

Hardware Requirements

To run our software on you will need:

Minimal setup (FULL HD):

Recommended setup:

Software will also run on older machines like Intel i3 processor + middle class graphic card. Indispensable are: Windows 10, graphic card with DX 11 support, USB 3.0 port, Kinect 2, projector.

Hardware setup

How to correctly place both Kinect sensor and the projector.

Augmented Reality Sandbox DIY

Sensor and projector placement without (left) and with (right) lens shift.
There are two things You'll have to bear in mind: the Augmented Reality Sandbox Software works best when the sensor is close to the light beam source and at the same time, it [sensor] should be placed approximately above the center of the sandpit. To meet both of these requirements we suggest using a lens shift projector. It may be slightly costlier, but will provide great quality of simulation and minimize errors.

Having the projector and Kinect far apart may result in parallel shifts in the projection. Those are usually not significant, but visible. We found that the best way to avoid this issue is to mount a lens shift projector close to the kinect and place them above the center of the sandpit. Such solution is only possible with this certain type of projector.

Augmented Reality Sandbox DIY

Remember that the Kinect sensor should be placed exactly above the center of the sandpit, facing downwards. See the overhead view image for clarification.

Example setup

Software requirements

Drivers and packages necessary to run KinectSandbox and modules

Operating system:

KinectSandbox

Kinect for Windows SDK 2.0

FBX Export

Software Calibration

Step by step tutorial.

Augmented Reality Sandbox DIY

1. Prepare the surroundings

For best results the application requires scrupulous calibration. The outcome of the process depends heavily on surrounding conditions, especially the lightning. It should be constant, evenly distributed and very slightly dimmed, soft daylight-like.

Make sure there are no flashing lights nearby, such as TV screens, or faulty light bulbs. Also cover the windows in case weather conditions (clouds, etc.) could affect lighting in the room.

The areas right next to the sandbox have to be nonreflective – avoid things such as oil-painted walls or tile floors. If necessary, cover them with white paper sheets.

Augmented Reality Sandbox DIY

2. Set up calibration boxes

To correctly gather calibration data, sensor needs smooth, flat and preferably white surfaces.

Our suggestion is to use cardboard boxes of three different sizes listed below. They should be arranged so that the edges of the same length contact each other and only the height varies. It’s best to not leave any gaps between boxes, however if they occur (eg. because of size of the sandpit), fill them with white paper sheets, so that the lowest surface is also plain white. Also, keep in mind that the boxes should cover all the space lit by your projector and ideally even stick out a bit.

Box 1 – 20x20x20cm

Box 2 – 20x20x15cm

Box 3 – 20x20x10cm

Use this scheme to set up the boxes, starting from the edge of the sandpit:

Boxes in sandpit 100cm x 60cm

Augmented Reality Sandbox DIY

3. Run the calibration software

During the calibration process you should be able to see a changing pattern, looking like the one on the right. Make sure it is on top of the projection and no other window is displayed above it.

Before running the calibration check if your display’s resolution matches that of your projector.

Calibration automatic mode:

  1. Backup the existing calibration file (D:\ar-sandbox.eu KinectSandbox…\KinectSandbox_Data\StreamingAssets\calib.xml) to your chosen location outside D:\ar-sandbox.eu KinectSandbox… folder; if the calibration software doesn’t work as intended, you can always restore the original file,
  2. Go to “Calibration_ar-sandbox.eu” folder,
  3. Run “autocalibration – start programs.exe” app as administrator,
  4. Wait about 30 seconds until you see a ‘Programs ready‘ notification,
  5. Run “autocalibration – calibration.exe” app as administrator,
  6. Wait about 2-3 minutes, until you see a ‘Calibration saved‘ notification,
  7. Copy the calib.xml file to D:\ar-sandbox.eu KinectSandbox…\KinectSandbox_Data\StreamingAssets\calib.xml (replace)
  8. Run AR-Sandbox app to determine whether the calibration process worked; keep in mind the AR-Sandbox app is designed to work with sand and it may glitch at sharp edges. If you are unsure about the result, try removing the boxes and applying sand instead. Also, slight projection shifts towards outer edges of the sandpit are possible and are a natural thing.

Calibration manual mode:

  1. Backup the existing calibration file (D:\ar-sandbox.eu KinectSandbox…\KinectSandbox_Data\StreamingAssets\calib.xml) to your chosen location outside D:\ar-sandbox.eu KinectSandbox… folder; if the calibration software doesn’t work as intended, you can always restore the original file,
  2. Go to D:\Calibration_ar-sandbox.eu\AR_Sandbox_Calibration folder,
  3. Run KinectServer app as administrator,
  4. Run ProjectorServer app as administrator,
  5. Run CalibrateEnsemble app as administrator,
  6. In CalibrateEnsemble open the calibration file (menu File > Open… > D:\Calibration_ar-sandbox.eu\calib.xml),
  7. Run calibration (menu Calibrate > Acquire) and wait until you see ‘Acquire complete’ message at the bottom of log window on the right side of the app window; you may need to left-click with your cursor outside the app window, as the Acquire screen will by default run in the background; this step should take approximately 1 minute, and you should be able to see changing vertical and horizontal pattern across the screen, implying the program is running correctly,
  8. Solve calibration (menu Calibrate > Solve) and wait until you see ‘Solve complete’ message at the bottom of log window on the right side of the app window,
  9. Save calibrated file (menu File > Save),
  10. Copy the calib.xml file to D:\ar-sandbox.eu KinectSandbox…\KinectSandbox_Data\StreamingAssets\calib.xml (replace),
  11. Run AR-Sandbox app to determine whether the calibration process worked; keep in mind the AR-Sandbox app is designed to work with sand and it may glitch at sharp edges. If you are unsure about the result, try removing the boxes and applying sand instead. Also, slight projection shifts towards outer edges of the sandpit are possible and are a natural thing.
  • In case the original calib.xml file doesn’t exist or the results of calibration are very poor: in CalibrateEnsemble create new file (menu File > New, make sure Number of Projectors and Number of Cameras is 1) and save it to D:\Calibration_ar-sandbox.eu\

Troubleshooting

It may happen that the calibration process doesn’t immediately give perfect results. This is mainly because it uses and depends on physical objects and can be affected by their imperfections. Usually it’s a matter of few simple steps to reach the wanted level of accuracy.

The most common problem is projection being shifted compared to the actual shape of the sand. Reason behind this is the program misinterpreting or having wrong input data. First thing to do in such situation is to re-run the calibration software. If it doesn’t help, you should try repeating the actions described in the first paragraph. As the lighting plays crucial role in the process, try changing it. Firstly, lower the projector’s brightness. Then, if necessary, brighten up the room. Avoid direct light sources and letting sunlight in.

Shift in the projection may also be a software issue. Check if resolutions match: projector’s resolution, Windows display, KinectSandbox resolution (you can find and edit it here D:\ar-sandbox.eu KinectSandbox…\KinectSandbox_Data\StreamingAssets\GlobalSettings) and finally the resolution described in the calib.xml file (find and edit lines <height>1080</height> and<width>1920</width>). Re-run the calibration.

If you encounter glitches in the KinectSandbox app, it doesn’t necessarily mean there is a problem with the calibration itself. Check the most important settings inside the app: borders and levels. You will find detailed instructions below.

Another problem that can occur is the projection going completely dark after launching the KinectSandbox app with a new calib.xml file (sometimes it is also a matter of tweaking levels settings). In such case go to D:\Calibration_ar-sandbox.eu\AR_Sandbox_Calibration, run the CalibrateEnsemble program as administrator, open the calib.xml file (menu File > Open…) from D:\ar-sandbox.eu KinectSandbox…\KinectSandbox_Data\StreamingAssets and check the number assigned to the display (menu Setup > Show Projector Server Connect Displays). You will see a number on the screen (should be either 0 or 1). Remember this number and then manually edit the calib.xml file (Open with Notepad). Find the line: <displayIndex>…</displayIndex> and write the display number in place of the dots.

One last thing to check is the number of lines in the newly prepared calib.xml file. It should be precisely 187. If it is not, it means the calibration process malfunctioned and has to be repeated. Pay close attention to all the steps. Restore the default calibration folder and re- run the calibration.

Should you still have problems with your calibration, keep the old and new calib files and contact us at [email protected]

Tips & Tricks

Before the calibration:

  • Be very careful when preparing the surroundings of your sandbox for calibration. Every obstacle that can be seen by the sensor is a potential cause for trouble.
  • If you have your projector-sensor setup mounted on a column, wrap the column in a plain cloth, especially if it’s metal and reflective.
  • Check if the Kinect logo lights up after you start the programs – if not, there may be a problem with the device/cable.
  • Open the Kinect for Windows SDK 2.0 software and run ‘Configuration Verifier’.
  • Make sure your setup is mounted steadily and the position of Kinect/projector won’t change – this will spare you recalibrating in the future.

If you encounter probems:

  • Check the settings of the KinectSandbox software (instructions below). It may be that the calibration is fine, but borders or sandbox levels are set incorrectly.
  • Open the calib.xml file with text editor and check for these lines: <height>1080</height> and<width>1920</width> (both are found towards the end of the file). Correct the numbers between the captions to match your projectors resolution if necessary.
  • Open the application folder (ar-sandbox.eu KinectSandbox…) and go to KinectSandbox_Data\StreamingAssets\GlobalSettings. Check if the resolution described in the file matches that of your projector and correct it if necessary.
  • Open projector0/camera0 in the Calibration folder and check the pictures inside. They will give you an idea what can be seen by Kinect as an obstacle.
  • Restore the default calibration folder.
  • Use manual mode as described above, instead of the automatic.

Operating manual

Quick overview of the most important settings inside the application.

Augmented Reality Sandbox DIY

Display orientation

When you first launch the application it may struck you that the picture is flipped. This is because of the way we construct our sandboxes and believe is the best way to do this (at least without a lens shift projector). If you put the projector on the floor and project the application on the wall it will look like the lower picture. The watermark is flipped and so are the borders (we will talk more about them in a moment). However, when you set the projector vertically, like presented on the left, and stand in front of your set up, you will be facing the picture properly.Don't worry if you already mounted your device and now have a flipped picture. You can always change it in Windows' or projector's display settings. If you do so, make sure to recalibrate your sandbox.

ekran2
Augmented Reality Sandbox DIY

Setting borders

Note: to save setting changes made inside the application, press Alt + F4 (exit). This applies to any adjustments made with the program running.

One of the most essential settings are the borders. Because Kinect has a 90º field of wiev, the area it sees is much larger than any sandpit and needs to be restricted. In the first picture you can see an example how borders can be set by default. Kinect sees the whole sandpit, but also some of the surrounding area. It may happen that there is an obstacle in that region, e.g. a reflective wall (see lower left picture). In such case, and this is a pretty common situation, your sandpit will end up looking like the last picture. It can also disturb the calibration process.

Restrict Kinect's field of view by setting your borders along the arrows, to the point when they become visible in your sandpit. Keyboard controls inside the app are: T,Y - Left, G,H - Right, U,J - Top, I,K - Bottom. If you have already calibrated your sandbox, you may need to do it again, or try running the app with the default calib file.

Augmented Reality Sandbox DIY

Distance from the sensor

Another important settings are Sandbox Top and Bottom Levels. They specify the range of the Kinect sensor. See image for more details.
Presented parameters are specified in the setting file. Their values are the distances in mm. The best way to achieve good results is to tape-measure the distances and then set the right values. It can be done either when the application is running (Z, X keys for Top Level; C, V for Bottom Level; values are shown on the screen), or in the setting file in application root folder (Settings.json in KinectSandbox_Data\StreamingAssets\Settings).  Remember you will have to exit the app to save your changes. Also, we recommend that the values You enter have a margin of about 50-100 mm in both directions.
In the graphic You can also see one parameter called WaterDropOffset. It is the distance above the Top Level of your sandbox, required to activate the waterflow. The higher the value, the higher You will have to lift your arm to make it rain. Also the active area will shrink due to the sensor's field of view. Offset value can be changed in the app (R, F) or in the setting file (Settings.json in KinectSandbox_Data\StreamingAssets\Settings). Value range 0-300.

To directly control basic water options use computer keyboard or mouse. Press space or middle-click mouse to reset water - it will sink into the ground. To disable water flow press 'b' or right-click mouse. The same goes for enabling water flow again. Note: disabling water flow does not reset current water, so You can have some in your drainage and then sculp it without unnecessarily pouring more.

Augmented Reality Sandbox DIY

Projection range

The last two parameters you will need to adjust are TerrainTop&BottomLevel. They control the projected colour range in your sandbox (unlike SandboxTop/BottomLevels which described physical values). Keys to control are W, S for bottom and Q, A for top. If you set the two values close to each other, distances between neighboring isohypses will shrink - this will make sense if you have a shallow sandpit. If you want to build high mountains and deep valleys, set the two values farther apart.

Two things to acknowledge: first - there is no other way to set those values than to experiment. For a standard construction (distance from Kinect to sandpit ~1,2 m) they should not depart far from the default ones. Second - TerrainBottomLevel value has to be lower than TerrainTopLevel – the number is higher, since the values are negative.

Note: pretty common mistake is to blame malfunctioned calibration for the projection being completely dark/white, when actually it is a matter of setting the TerrainLevels right. If your SandboxBottomLevel exceeds 1200, you will probably need to decrease TerrainBottomLevel a bit to be able to see colours.

Default settings
Top level decreased + bottom level increased
Top level decreased
Top level decreased + bottom level decreased

Detailed information about those and any other available settings can be found here.

Button Controller

Simple tool for basic control over the application.

Button controller is used to switch the water simulation on and off, or reset it. With many people around the sandbox it is easy to flood the area. To avoid it, switch the water off and then back on after you are finished building. The water that is already flowing won’t disappear, until you reset it.

The button uses keyboard/mouse controls to interact with the application – space/middle-click is water reset and ‘b’/right-click is water on/off. You will need a control board that emulates a computer keyboard (e.g. Arduino Leonardo). It will write space when the button is pushed and ‘b’ when held. You can download the script here (you will also need software to upload it onto the board) and connection scheme here. Another way is to use a standard computer mouse, but replace its original buttons with external ones.

You can choose any button you want, as long as it is a normally open, monostable one. Mount it to your sandbox in a well-exposed place. To avoid it getting stuck with sand, choose a place above the sandpit level.

Below you will find a video tutorial with step-by-step instructions.

Touchscreen module

Additional feature for expanded functionality

Augmented Reality Sandbox DIY

Screen setup

As the touchscreen module is now available as a software extension, you can implement it in your custom Sandbox. This allows for quick control over the application via easy to use interface.

For this feature to work,you will have to find a touchscreen that has exactly the same resolution as your projector. Then, when setting up both screens in Windows, make sure they are next to each other (horizontally, not vertically). The projector should be the main display and touchscreen the secondary one.

Augmented Reality Sandbox DIY

Wireless control

Instead of a standard touchscreen you can use a tablet, your mobile phone, or any other device capable of connecting with a wi-fi network. First, set up the connection. You can either connect both devices to the same wireless network or, in case you want a faster and more reliable connection, use an additional router you will connect to your PC and use as a hub.

Next step is installing a screen-casting software on both devices. We use and recommend this app. After the installation, open spacedesk on your mobile device and connect with the PC. If you have the KinectSandbox  software running, it will restart automatically. You may need to configure Windows display settings. Make sure the projector is the main screen and the setup is ready to go.

Below you will find a video tutorial with step by step istructions.

FAQ

Your questions

Do you mean by “Kinect PC, Kinect X-BOX with PC Adapter” that both a Kinect for windows (version 1 or version 2.0?) as well as an Kinect for XBOX (1414/1473 or do you mean XBOX one?) with the (expensive J) adapter work? And do you know a webshop where we can still buy one of them (since they are no longer produced if I am correct)?

You will need Kinect 2 PC (it is Xbox ONE + PC adapter) You can buy refurbished one from the eBay.

Would the system also work with an intel Realsense camera (easier to find)?

Our system doesn't work with realsense. It is much much worse depth detector than Kinect 2. With Kinect 2 we get very accurate 3d model. We wish to use Azure Kinect in future.

Is there a way to incorporate the basic buttons you also provide with your systems if we build the system ourselves?

We are going to release full video tutorial, as well as we want to update existing one. Operating buttons is very simple. You can use mouse or wireless mouse to be interface. Just get wires out form mouse buttons and connect your button. We also provide Arduino code for Arduino Leonardo/Micro pro control.

Do you expect that we have to recalibrate if transport the system a lot?

If you will make rigid frame for kinect + projector it will be stable. We have unit with wheels and tower that automatically goes up and there is no need to re-calibrate when moving unit. Calibration is very simple by the way - you need just white boxes.

Do you have a discount for non-profit organizations, or is the price the same for companies and educational organizations?

Contact us, write about your project and let us think. At this moment price is very competitive.

How do you count the “visitors a month”?

We don't 🙂 We only estimate basing on our experience. We wanted to have affordable price even for small organizations but if there is a science center with thousands of visitors a day they have to pay. It's just about being fair.