Check that all platforms calculate humidity measurements same way

[markoaamunkajo]

Description:

Customer contacted us with his observation that in iOS application absolute humidity readings are changing "wildly" as the temperature changes.

Let's check humidity calculation formulas on all platforms just to make sure we are using same on all.

[priyonto]

The absolute humidity is calculated with relative humidity which is dependent on air temperature. I find it logical that change in temperature affects humidity. However, I am keen to know more about the "wildly" situation. And, I am going to double check this with android app as well.

[markoaamunkajo]

@priyonto please share formula so we can collect and compare

[priyonto]

@markoaamunkajo iOS is using the default methods provided by Apple for measurements. You can find more about the methods here, but I am unsure whether that will be helpful because we don't know about the internal calculation.

Documentation: https://developer.apple.com/documentation/foundation/measurement

[laurijamsa]

I quickly checked abs humi graphs of a same sensor and iOS looks different than the others:

iOS:

Web:

Android:

Also dew point calculations are different on iOS than others:

iOS:

Web:

Android:

[markoaamunkajo]

@laurijamsa @priyonto so conclusion is that Apple uses different method and there is nothing we can do about it?

[priyonto]

@markoaamunkajo Kind of, but I wouldn't say we can't do anything about it. I mean, we can probably do the custom implementation if needed.

But, the reason for mentioning you in this card is to double-check the issue and confirm whether you can reproduce it. I have tried to reproduce it on my end, but I could not find any dissimilarities between the android and the iOS app.

[markoaamunkajo]

@laurijamsa I was not able to proof a difference on single sensor yet between various platforms. Here are my attempt csv's:

Home outdoors _20220821-1709_Android_relative.csv Home outdoors _20220821-1709_web_relative.csv Home outdoors _20220821-1709_iOS_relative.csv

Home outdoors _20220821-1658_android_dew.csv Home outdoors _20220821-1659_web_dew.csv Home outdoors _20220821-1658_ios_dew.csv

[laurijamsa]

It may be that the issue https://github.com/ruuvi/com.ruuvi.station.ios/issues/1070 was the problem here. But I'll keep this issue self-assigned and will try to reproduce the problem before closing.