Get pitch/yaw/roll from a rotation matrix

Blitz3D Forums/Blitz3D Programming/Get pitch/yaw/roll from a rotation matrix

bytecode77

(Posted 2009) [#1]

hi!

it is easy to get the position of a position-only-matrix. the same applies for the scale matrix, but what about the rotation matrix?

i have a matrix storing only the rotation and need a function that gets the pitch/yaw/roll from this matrix?

any math specialists here?
thank you :)

Gabriel

(Posted 2009) [#2]

http://www.euclideanspace.com/maths/geometry/rotations/conversions/matrixToEuler/index.htm

bytecode77

(Posted 2009) [#3]

thats not workign for me. i allways get zero for pitch, yaw and roll.

Difference

(Posted 2009) [#4]

My version of the code from that site below.
It gives quite good results, but I don't think they are 100% correct.

You will at least have to experiment with the signs for the rotations to get it correct.

I'm also not sure what to do with the determinant, so if you can help out it will be much appreciated.

I have the same question here: /Community/posts.php?topic=82644#932186

	Method Decompose()

		_Decompose()		
		
		ry =	heading '(rotate about y) 'roll
		rz =	attitude '(rotate about z) 'pitch
		rx =	bank '(rotate about x) yaw
	
	End Method


	Method _Decompose()


		' get translation		
		Tx = a4
		Ty = b4 
		Tz = c4

		Local rm:aiMatrix3x3 = New aiMatrix3x3	
			
		'transpose to row format instead of colums if needed (not shown here)
		rm.a1 = a1 ; rm.a2 = a2 ; rm.a3 = a3
		rm.b1 = b1 ; rm.b2 = b2 ; rm.b3 = b3
		rm.c1 = c1 ; rm.c2 = c2 ; rm.c3 = c3	
		

		Sx = Sqr( rm.a1*rm.a1 + rm.b1*rm.b1 + rm.c1*rm.c1 )
		Sy = Sqr( rm.a2*rm.a2 + rm.b2*rm.b2 + rm.c2*rm.c2 ) 
		Sz = Sqr( rm.a3*rm.a3 + rm.b3*rm.b3 + rm.c3*rm.c3 )


		Local det:Float =  rm.a1*rm.b2*rm.c3 + rm.a2*rm.b3*rm.c1 + rm.a3*rm.b1*rm.c2 - rm.a1*rm.b3*rm.c2 - rm.a2*rm.b1*rm.c3 - rm.a3*rm.b2*rm.c1


		

	
		If sx Then
			rm.a1:/sx	
			rm.b1:/sx	
			rm.c1:/sx	
		EndIf
		If sy Then
			rm.a2:/sy
			rm.b2:/sy	
			rm.c2:/sy	
		EndIf
		If sz Then
			rm.a3:/sz
			rm.b3:/sz	
			rm.c3:/sz	
		EndIf	


	'	Sx:* Sgn( det)
	'	Sy:* Sgn( det)
	'	Sz:* Sgn( det)


		


		If (rm.b1 > 0.998) ' singularity at north pole
			heading  = ATan2(rm.a3,rm.c3)
			attitude = 90 'Pi/2
			bank = 0
			DebugLog "' singularity at north pole ******************************************************"
			Return
		EndIf
		
		If (rm.b1 < -0.998)' singularity at south pole
			heading = ATan2(rm.a3,rm.c3)
			attitude = - 90 '-Pi/2
			bank = 0
			DebugLog "' singularity at south pole ******************************************************"
			Return
		EndIf
	
		heading = ATan2(-rm.c1,rm.a1)
		bank = ATan2(-rm.b3,rm.b2)
		attitude = ASin(rm.b1)		


Return

bytecode77

(Posted 2009) [#5]

		heading = ATan2(-rm.c1,rm.a1)
		bank = ATan2(-rm.b3,rm.b2)
		attitude = ASin(rm.b1)

thats the code i'm using. i dont get it - after looking closer to the results, i found that the results are between zero and two.

EDIT: i think it starts working after i multiplied with 180.0/PI
thanks guys :)