Plumb-bob application support:

You have a question, you need some help with the application, you have a suggestion to add a new feature?
You can send an email to our support team.


    Q: How come that the plumb-bob line is not perfectly vertical?

A: The sensor quality can vary a lot from one device model to another.
This is why the "Plumb-bob" application contains a calibration feature. Click on the calibration button of the top menu bar to activate it.
The calibration page contains 3 sections. The sensor calibration part is the last one.
The calibration is done automatically and requires a flat surface that is used as a reference horizontal plane. This is a 2 steps process: put first the phone on the surface, screen side down, then do another measurement with the phone on its side.
For some sensors for which virtual vertical and horizontal axis are not perfectly orthogonal, this calibration process is not sufficient. This is why a manual adjustment can be made to the calibration delta angles. Our advice is to adjust the vertical calibration only.
A video tutorial is available here:

    Q: How can I measure the camera angles of view?

A: When the values reported by your phone are incorrect, you need to set the camera angles of view manually (this is the second part of the calibration page). An easy way to do it is to put your phone on the side of a table, with the camera that extends beyond the edge of the table and that is looking down. Then, measure the height of the table (H) and measure, on the ground, an image side length (w). The corresponding angle of view can be computed with the following formula:

a = 2 . atan( w / 2.H )

The camera angle of view calibration expects a value in degrees.
If you click on the wizard buttons at the bottom of the calibration page, a new page will open to guide you and compute this angle for you.

    Q: It's difficult to have a stable plumb-bob vertical line. How can you help me?

A: The sensor is quite sensitive. And holding the device in the air without shaking is difficult. Therefore, it is recommended to put your phone down on something.
The application contains a snapshot feature (press the camera icon on the top right corner to activate it). In this mode, it is no longer required to hold the device in the air.
You can precisely adjust the position of the plumb-bob in the picture and you can also rotate the frame to align it with a wall that is not directly facing you.