iPhone Compass: What is this red area about?

[desertman]

When using Compass I see on and off some parts of the degrees ring "doubled up" in red. See attached picture.

What is this red area about?

Why is it sometimes there and sometimes not (even if I use Compass from the same position at different times)?

Thanks!

 

[macintoshmac]

When using Compass I see on and off some parts of the degrees ring "doubled up" in red. See attached picture.

What is this red area about?

Why is it sometimes there and sometimes not (even if I use Compass from the same position at different times)?

Thanks!

This is not sometimes there and sometimes not. It is a useful feature that gets activated when you tap anywhere above the reading in the largest font in the app. The idea is, when you tap, it sets the current reading as reference and then when you turn the phone in either direction, it tells you how much you have deviated from the reference point you set - that difference is being highlighted in red.

 

[desertman]

Thanks. I can replicate this. At least I don't wonder anymore why it's sometimes there and sometimes not.

I don't know much about compasses, basically just that they tell me where North is. In a practical sense - what is this marking good for, for what is it being used?

 

[macintoshmac]

Thanks. I can replicate this. At least I don't wonder anymore why it's sometimes there and sometimes not.

I don't know much about compasses, basically just that they tell me where North is. In a practical sense - what is this marking good for, for what is it being used?

Let's take the image that you uploaded here.

At the time you inadvertently tapped within the app, the iPhone was pointing 276 degrees West.

Now, let's say you wanted to walk straight. Then, in the picture, it is showing that you are now facing 180 degrees South, almost perpendicularly left of the intended direction you wanted to walk towards.