This page is for the development version of our internal Android App Prototype. v202403a

"SPINSIGHT beta" Android App Prototype Help

The Android App named "SPINSIGHT beta" is an development prototype that we use for technology development. This App is not intended for general use yet. Instead, we advice people to use our iOS App that works on recent iPhones and is easier to use.

You get access to the iOS App for your iPhone after you buy a Starter Kit, see our main App page: https://spinsight.com/app/

More information can be found on our FAQ here: https://intercom.help/spinsight/en/

The rest of this page is relevant only for the Android beta App.

With the SPINSIGHT App you can measure Spin & Speed of your table tennis balls. Typical applications are service training and top-spin training. In order to fully use the SPINSIGHT App you need a compatible smartphone that is capable of high-speed video and printed SPINSIGHT balls.

Getting started

For a quick introduction see our separate page: Getting Started

Installing the App on Android

We need the e-mail-address of your Play Store account to add you to the list and send you the installation link. Other people cannot install the app. Some region limitations may apply.

First start

The app will ask for acceptance of our terms and conditions.

Settings

GET CAMERA PERMISSION

Visible if camera permissions are missing. Click on the button and then allow camera access.

If access has been denied repeatedly you need to grant it manually in the app settings.

RUN TESTS

Before using the device you need to run some tests. Click on the button and then click Start in the popup window. The tests may take a few minutes.

OFFLINE

The device is offline. Check your internet connection.

START

This button is visible if the device is ready for the measurement. Click to start the measurement.

User level

Depending on the user level we show more or less options. The following user levels are available:

• Basic - after everything is already set up and users just want to START the measurement.
• Advanced - options most users need to set up the device.
• Expert - additional options some users need.

Ball Type

Depending on the type of ball that you have, you need to set the settings.

• SPINSIGHT ball - the official printed spinsight ball.
  • This offers high precision measurement.
• Normal Ball - works with any ball but does not support spin measurement.

Measurement Range

Depending on the ball type, smartphone capabilities and other settings, different measurement ranges can be selected.

• 150 rps, 90 km/h
  • Default mode.
• 100 rps, 60 km/h
  • If 150 rps is not available or doesn't work well.
  • Saves Battery.
• 75 rps, 45 km/h
  • For training serves.
  • Works with lower light.
  • Can handle flickering lights better.
  • Saves Battery.

Server

You can change the server setting to access the experimental server:

• Stable
  • The default setting.
• Experimental
  • New features, some bugs, sometimes offline.

Feature Keys

Here some special features can be enabled by adding some text.

• FULLFPS - Only use full 120/240 FPS instead of adjusted frame rates.
• elite - The elite-ball becomes selectable.

Measure Light Level

Starts the light measuring mode, see section Light.

Video Resolution

Optional setting the video resolution.

• Auto - the default setting for your device.
• HD - The default resolution (1280x720).
• FullHD - Bigger resolution (1920x1080). This offers a larger measurement window but needs more processing power and is problematic on many devices.

Effective horizontal field of view

Default is empty (=automatic).

A precise value may be improve the measurement quality. Typical HFOV values are in the range of 60 to 90 degrees.

When attaching a zoom lens to the smartphone the value needs to be measured.

Measuring the HFOV

Start the measurement mode and measure the WIDTH of the image at a certain DISTANCE from the camera.

The formula is HFOV = 360/pi * arctan(0.5*WIDTH/DISTANCE)

Example: Phone placed on a table at 72 cm elevation and it sees an image width of 92 cm on the floor results in 67.4 degrees for HFOV.

Mains Frequency

Frequency of the electrical grid. All of Europe has 50 Hz, North America has 60 Hz, Japan is mixed.

This setting is used in the 75 rps measurement range to reduce the problems with flickering lights.

Disable Flicker Detection

Activaing this switch will disable the flicker detection.

Critical Battery Level

The battery level percentage at which the measurement stops. If a power supply is connected the measurement works even below this level.

The default value is 20 percent. Some older phones with weak batteries are unstable at higher levels. If you experience system crashes increase this level or connect a power supply to the phone.

The "Battery Low" warning starts 10% above "Critical Battery Level" - between 20% and 30% by default.

When the phone is charging you can measure at any battery level.

Skip Camera Setup Dialog

Enabling this will directly go to the measurement. This is useful when doing repeated measurements in the same location.

Ball Detection for Focus

• Auto - Default setting. Ball detection in the focus screen is enabled.
• Off - Don't use ball detection to help with focus setting.

Skip Feedback Dialog

Enabling this will skip the feedback dialog after the measurement session.

Default is enabled.

Enable Remote Control

Enabling this will allow other devices such as the Web-Frontend on the Tablet to send commands to this device. Necessary to Start & Stop the measurement from the Web-Frontend on the tablet.

Default is disabled.

Remote Control Permssions

Enter the device IDs of the devices that are allowed to send commands. Other devices will be ignored.

Enable all devices to send commands by entering * here.

On the frontend settings you may see the frontend device ID in the form SW1234 or XW1234.

Position Settings X, Y, Z, R

The camera position is necessary for the measurement window display and position based measurements.

Default values for a tripod 170 cm camera height and 100 cm from the table edge:

• X: 0.0
• Y: -1.0
• Z: 0.94
• R: 0.07

Updating these values from the frontend is under development.

Open Privacy Agreement

Opens the privacy agreement page that you agreed to in a browser.

Reset Device Identity

This will reset the device identity and it will give your device a new broadcast ID. The display devices you have connected in the past (via QR-code or link sharing) will not receive new measurement data. You will have to reconnect them.

This can be used if you do not want others to see your new measurement data.

Send Optional Usage Data

If this option is enabled it will send data about how the app is being used and errors to a database. We use this data to improve the app experience and fix bugs. Sending this data is optional.

Device Nickname

Optional name for the device that can be used when managing multiple measurement devices.

Phone placement

The default placement of the phone for measurement with SPINSIGHT balls is on a tripod 150..180 cm from the floor, next to the table 50..100 cm from the table edge looking down at the table.

The alternative placement with a small tripod is over the table looking down at a 45° angle.

Other phone placements are possible if the light and background are good.

General Requirements

• Enough good light.
  • 300 Lux minimum.
  • 600 to 1000 Lux recommended.
  • >10000 Lux many phones have problems.
  • Light not flickering.
• A dark and steady background.
  • The TT-table, a dark floor, a dark wall, dark boundaries, dark cloth.
• The ball has to pass through the measurement window.
  • Minimum and maximum distance between ball and camera. The range depends on smartphone and settings.
  • The ball must be visible in the camera image.

Starting the Measurement

Focus Mode

Place the ball on the table before you start the measurement. The app assumes that a ball is on the table at about 10 cm from the net and center line. If the Aimbot is enabled (enabled is the default setting) it will automatically search for the ball.

With the button "Adjust Focus" you can enter the focus mode.

• Place a ball on the table next net slightly behind the center line.
• Ensure that the ball is in the circle in the center of the screen.
• Push the "Auto" button to activate autofocus.
• Manual adjustment if "Auto" fails to produce good results.
  • Adjust the ISO value with +/- Buttons such that Light is "Good".
  • Adjust the Focus distance with +/- Buttons such that the image has best sharpness.
• Exit via the OK button.

The values are stored and readjusting focus is usually only required if you change the measurement mode or location.

Check the measurement window

The measurement window is the area in front of the camera where the ball can be measured successfully.

Adjust the camera angle such that it points to the the area where the ball passes over the net in the center of the table.

Play some balls over the center of the table. They should result in measurements and display the result.

Typical distance ranges are:

• 75 cm - 125 cm in HD mode without Zoom
• 120 cm - 200 cm in HD mode with 1.6x Zoom
• 100 cm - 250 cm in HD mode without Zoom

Result display

The result consists of three major components

• spin amount in rps (rotations per second)
• spin axis - an arrow that shows in which direction the ball rotates
• speed amount in km/k (kilometers per hour)

In the integrated view we show the spin amount inside the circle with an arrow for the spin axis. The speed amount is below the circle.

In the single line view we show the spin amount next to the circle with the arrow and the the speed amount.

Spin amount

The spin amount is given in rotations per second (rps).

In order to get rotations per minute (rpm) you multiply this number by 60. E.g. 150 rps = 9000 rpm

Typical values for amateur players are

• 20-60 rps for service with top-spin,
• 20-40 rps for service with back-spin,
• 40-60 rps for kick-kick,
• 60-120 rps for top-spin returns.

Spin axis

The spin axis arrow shows in which direction a dot in the center of a ball would move if you stand behind the ball and watch as it flies away from you.

For a ball with top-spin the dot would move up and vice versa for a ball with back-spin the dot would move down.

For a ball with left/right spin the dot would move left/right.

If the spin axis is not clear (e.g. only low spin or a high amount of corkscrew spin) there will be no arrow shown.

Spin colors

The spin number and axis may be colored according to this scheme

• cyan - top-spin
• magenta - back-spin
• purple - side-spin (right or left)
• grey - other spin

When the spin axis is not clear (e.g. only low spin or a high amount of corkscrew spin) it will show grey.

Speed amount

The speed amount is given in kilometers per hour (km/h).

In order convert it to miles per hour multiply this value by 0.62. E.g. 50 km/h = 31 mph.

Typical values for amateur players are:

• 5-15 km/h for slow service,
• 20-30 km/h for fast service,
• 30-50 km/h for kick-kick,
• 40-60 km/h for top-spin returns.

Left and right player

The left player is on the left side as seen from the camera of the measurement smartphone. If you are not sure about the sides, simply play a ball and see which side updates the numbers.

Using a second device for result display

You can connect another device to the server to show the measurement results.

Sharing the link

In the main menu and in the hamburger menu there is a QR-code that you can scan with your second device. Alternatively the link can be shared via some messenger app.

On your display device, the page opens in the web browser and it will show the live results for both sides.

Sound Feedback

In the hamburger menu you can adjust the sound settings.

Notifications

General notification messages like "Ready", "Online", "Offline" etc.

Player Side

Play the sound for the left and/or right player.

Usually only one player side is enabled and the coach/robot side is disabled.

Sound Type

Beep changes pitch with the value. Useful for repeated strokes and general feedback.

The Voice reads the value. Useful for service training in a calm environment.

Value Type

Choose between sound feedback on Speed and Spin.

Appendix

Light measurement

The app has a light measurement tool integrated that uses the smartphone light sensor.

Start via "Measure Light Level" in the settings menu.

Place the phone on the table and read the illumination value.

• below 300 Lux - Measurement will probably not work
• 300 to 600 Lux - Low speed modes should work
• 600 to 1000 Lux - High speed modes should mostly work
• 1000 to 10000 Lux - All modes should work reliably

For alternate smartphone placements the light measurement at different angles can be useful.

Error messages

When the ball detection encounters an error a message will be displayed. Errors caused by a passing ball are displayed on the side where the ball came from. Other errors are displayed in the center.

• Too close - the ball was too close to the camera.
  • Try to play the ball a bit further away from the camera.
  • Place the camera closer to your playing area.
• Too far - the ball was too far from the camera.
  • Try to play the ball a bit closer to the camera.
  • Place the camera closer to your playing area.
• Too fast - the ball was too fast for a successful measurement.
  • Play the ball a bit slower.
  • Increase the measurement range in the configuration menu.
• Too slow - the ball was too slow for a successful measurement.
  • Play the ball a bit faster.
• Spin too high - the detected spin exceeds the measurement range.
  • Ensure that the ball has dots.
  • Ensure that the ball being played matches with the ball settings.
  • Play the ball with less spin.
  • Increase the measurement range in the settings.
• Too dark - the ball was too dark.
  • Adjust the ISO.
  • Check the light conditions and increase the light.
• Too bright - the ball was too bright.
  • Adjust the ISO.
  • Outdoors: Go to a shaded area without direct sunlight.
• Processing error - the data processing did not produce good results.
  • Check the camera placement.
  • Check the background.
  • Ensure that the ball being played matches with the ball settings.
• Offline - your device has no connection to the server.
  • Check the internet connection.
• Measurement is displayed but no sound is being played
  • Check the player side configuration in the hamburger menu.
  • Check the other sound settings.
• No ball detection at all
  • Check if the measurement is actually running.
  • Check if the ball is actually passing through the measurement window.
  • Check the camera placement.
  • Check the background.
  • Adjust focus distance and ISO.
  • Check the internet connection.
  • Restart the App.