Quote from Bob Smith :

The vector is likely in m/s, and thus so will be the speed you obtain from calculating the length of the vector. If you are comparing to mph or km/h, then you just need to scale the value in order to get it to match. There should be no need to re-orientate the vector for heading, pitch and roll for the purposes of speed location.

Without more details as to why you think the numbers you are getting are wrong, that's my best guess.

Yes, we controlled again the mph and km status. We adjust the selection of speed as km. We cannot obtain the right value. While we are playing the game, for instance we are driving with 40km/h but we are receiving 60km/h or more. We multiplied with 3.6 for change in m/s to km/h. and also tried to divide with 1.6 to make sure that if something wrong with the km/h and mph issues.

we taking datas from game over the outsim. we adjusted the heading, pitch and roll. But we cannot calculate vector velocity. We have 3 float vectoral values. How can we calculate exact speed value.

we are trying this formula : speed = square root( x^2 + y^2 + z^2 ).
But we thing this formula is wrong...