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

Russ, Tom Tom.Russ at medma.uni-heidelberg.de
Fri Dec 13 16:36:13 CET 2019

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 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>

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