Accuracy

This page explains how to get a good accuracy. This can be helpful to you for example if you experience situations where the flags seem to move during measurements, making those measurements approximative.

The app analyses the images of the video and relies on details identified automatically on these images. In good conditions, the measurement error is generally of the order of 2%. These conditions include:

  • good lighting
  • textured (not uniform) floor
  • lack of reflection on the floor

If you want to improve the accuracy, there are 3 steps to keep in mind :

1- Make a good floor detection

2- Check the floor detection

3- Drop the points precisely

1- How to make a "good" floor detection?

Please first check the TIPS for floor detection.

Additionally, try to quickly detect a large portion of floor : the biggest portion you detect, the higher the accuracy will be.

Once the floor is detected, take 20s more to scan the floor all around you. The App will silently improve the floor detection until you drop the first point.

2- How to check the floor detection?

The app puts all the points you drop on the surface that was detected as the floor. In some cases (like reflections) the app may find a surface a little upper or lower than the real floor. This may reduce accuracy.

To check that the floor is at the right place, just drop a flag anywhere on the floor, near a detail that you can see on the floor. if the floor is well detected, the flag will really seem to be placed on the ground. Move around it : it should always stay at the same place on the floor.

If you feel the floor was not detected correctly, just give it another try.

3- How to drop the points precisely?

If you aim at a point that is several meters away, it is likely that you won't drop the flag at the right place. As a consequence, you should not hesitate to move in order to get close to the points you want to add. If possible, drop your points from above.

Another important thing is to avoid to cross dark areas and never hide the device lens. As a matter of fact, the app relies on what it sees on the video. As a consequence, it may get lost for a few seconds in dark areas. During this time the device may not record properly its move which can lead to a shift of the former points.

You should also avoid to move too quickly : quick moves make the video blur and prevent the app from identifying details.