[Gate-users] Rotation of Daughter Volume inside rotated mother volume

[Russ, Tom]

Dear GATE community,

I am having troubles with geometry definitions regarding rotations.
I want a slanted tungsten wire (23°) parallel to the YZ-Plane inside a water cylinder with ground area parallel to the YZ-plane.
Creating a mother volume as follows (world volume has no rotation):

/gate/world/daughters/name WaterCylinder
/gate/world/daughters/insert cylinder
/gate/WaterCylinder/geometry/setRmin 0. mm
/gate/WaterCylinder/geometry/setRmax 70. mm
/gate/WaterCylinder/geometry/setHeight 140. mm
/gate/WaterCylinder/placement/setRotationAxis 0 1 0
/gate/WaterCylinder/placement/setRotationAngle 90. deg
/gate/WaterCylinder/setMaterial Water

and a daughter volume inside:

/gate/WaterCylinder/daughters/name TungstenWire
/gate/WaterCylinder/daughters/insert cylinder
/gate/TungstenWire/geometry/setRmin 0. mm
/gate/TungstenWire/geometry/setRmax 0.025 mm
/gate/TungstenWire/geometry/setHeight 137.0 mm
/gate/TungstenWire/setMaterial Tungsten
/gate/TungstenWire/placement/setRotationAxis 0.1955 -0.9610 -0.1955
/gate/TungstenWire/placement/setRotationAngle 92.27 deg

For these commands I made 2 assumptions:


1.       GATE is handling daughter and mother volume rotations in this order: 1. Daughter volume is rotated, 2. Mother (and all daughter volumes) are rotated

2.       You cannot rotate a volume with 2 consecutive rotation commands as in
/gate/TungstenWire/placement/setRotationAxis 0 1 0
/gate/TungstenWire/placement/setRotationAngle -90 deg
/gate/TungstenWire/placement/setRotationAxis 1 0 0
/gate/TungstenWire/placement/setRotationAngle 23 deg

So I combined those 2 axis-angle rotations to a single rotation according to geometrical laws.

My Problem is now:

This is working totally fine for a slanted wire parallel to the XY-plane.
But if I want to execute these commands (seen above) in the same fashion for a slanted wire parallel to the YZ-Plane, the rotation is not executed correctly (see attached image, wire is white and not slanted).
In fact, this wire is not slanted about 23° in any direction, it is just parallel to the z axis.

Are my assumptions wrong or is GATE really not handling these commands incorrectly?

Any help is really appreciated.
Best regards,

Tom

=============================================

Tom Russ, M.Sc.
Projektgruppe "Image Guided Interventions"
Computerunterstützte Klinische Medizin
Medizinische Fakultät Mannheim
Ruprecht-Karls-Universität Heidelberg
Theodor-Kutzer-Ufer 1 - 3
68167 Mannheim
Tel. +49 621 383-6552
E-Mail: Tom.Russ at MedMa.Uni-Heidelberg.de<mailto:Tom.Russ at MedMa.Uni-Heidelberg.de>
http://www.umm.uni-heidelberg.de/inst/cbtm/ckm/

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