It may be that you're misunderstanding what a magnetic field is.ultrazapp wrote: ↑Fri Sep 01, 2017 5:38 pm... I have just read the data sheet that Dave posted cover to cover and it tells me how it works, that it reads a magnetic field and the Gauss range that it measures but it does not tell me what area it is measuring. For example is it measuring the magnetic field on my desk, the room that I am in, my house or at an extreme my town?
I want to fly the Pi and the sense hat from a quadcopter and use the sense hats instruments to measure the environment at about 200 feet in altitude for a PhD project on honeybees, ultimately to produce a 3D graph/map of the area as we know that honeybees use the earths magnetic field to navigate. Guaranteed the first thing my supervisor at Uni is going to ask me is "What does it measure and over what physical area, and Er prove it son"
I have used the data produced from the sense hats magnetometer data to produce the attached 3D graph which as I thought shows magnetic peaks, troughs, valleys and mountain ranges that the bees are likely to use to navigate, but Im really struggling to put any meaning to the image as I have no idea of the physical area being measured as in Length x Height x Width?
He talks about lines and Maxwells for the amount of field, and Gauss (what you're measuring) and lines per square inch.The definitions below gives 1 Gauss as 6.45 lines/in^2, just as JW says, and I've verified by calculation. Hope it helps.
1 Max = 1 Line
since 1 Gauss = 1 Max/cm^2,
Simple conversion(1/cm^2 to 1/in^2) gives:
1 Gauss = 6.45lines/in^2
gauss (G or Gs) 
the CGS unit of magnetic flux density. A field of one gauss exerts, on a current-carrying conductor placed in the field, a force of 0.1 dyne per ampere of current per centimeter of conductor. One gauss represents a magnetic flux of one maxwell per square centimeter of cross-section perpendicular to the field. In SI units, one gauss equals 10-4 tesla. The unit is named for the German mathematician and astronomer Karl Friedrich Gauss (1777-1855).
a CGS unit of magnetic flux, equal to 10-8 weber. In a magnetic field of strength one gauss, one maxwell is the total flux across a surface of one square centimeter perpendicular to the field. This unit was formerly called the line . The newer name honors the British physicist James Clerk Maxwell (1831-1879), who presented the unified theory of electromagnetism is 1864.
line (li) 
a former name for the maxwell, the CGS unit of magnetic flux. The unit was called the line because magnetic fields were traditionally represented by lines depicting the direction of the field; the idea was to quantify the strength of these lines. This is a small unit, so fields were often measured in megalines; one megaline is equal to 0.01 weber.
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