GDML back to FreeCAD workflow

[bxyzhu]

Hi Keith,

I came across some of the GDML workbench and I'm trying to use it for a potential use-case that is probably atypical and the reverse of what normal users would do. What I want to do is to convert a GDML file to back into a CAD file to be used and modified in other modeling tools.

I tried a simple test by loading a geometry that has a spherical shell that changes with different thicknesses at different solid angle bins. I'm able to just open and import the GDML file within FreeCAD and it looks like the sphere was built correctly with the correct radii. However, upon further inspection, it looks like the volumes weren't filled in properly for the shells (as in, it looks like only the surfaces are loaded). Is there an import option or setting within FreeCAD to do this correctly?

Here's the cross-sectional view:

The GDML snippet for the spheres:
<sphere name="Al_shielding_1" rmin="6.0" rmax="7" startphi="0.0" deltaphi="0.2*pi" starttheta="0.0" deltatheta="pi"/> <sphere name="Al_shielding_2" rmin="6.0" rmax="10" startphi="0.2*pi" deltaphi="0.06*pi" starttheta="0.0" deltatheta="pi"/ <sphere name="Al_shielding_3" rmin="6.0" rmax="12" startphi="0.26*pi" deltaphi="0.34*pi" starttheta="0.0" deltatheta="pi"/> <sphere name="Al_shielding_4" rmin="6.0" rmax="14" startphi="0.6*pi" deltaphi="0.3*pi" starttheta="0.0" deltatheta="pi"/> <sphere name="Al_shielding_5" rmin="6.0" rmax="15" startphi="0.9*pi" deltaphi="0.38*pi" starttheta="0.0" deltatheta="pi"/> <sphere name="Al_shielding_6" rmin="6.0" rmax="17" startphi="1.28*pi" deltaphi="0.14*pi" starttheta="0.0" deltatheta="pi"/> <sphere name="Al_shielding_7" rmin="6.0" rmax="19" startphi="1.42*pi" deltaphi="0.02*pi" starttheta="0.0" deltatheta="pi"/> <sphere name="Al_shielding_8" rmin="6.0" rmax="20" startphi="1.44*pi" deltaphi="0.2*pi" starttheta="0.0" deltatheta="pi"/> <sphere name="Al_shielding_9" rmin="6.0" rmax="25" startphi="1.64*pi" deltaphi="0.36*pi" starttheta="0.0" deltatheta="pi"/>

[KeithSloan]

Thanks for reporting.

Okay I tried to create a test file but for some reason this is ignoring the physvols, which is bug with import I am not currently spotting.
testShell.gdml.txt

I also changed so that the it uses the first physvol as world, this had a problem so I have refactored the GDMLSphere object code,
in branch makeConeFix
testOneSphere.gdml.txt

Are you able to test the branch makeConeFix ?

Are you able to supply your test file?
Github will not allow gdml file type, so one needs to either zip (Which is allowed or add txt)

Thanks

[KeithSloan]

testOneSphere1.FCStd.zip

With refactored GDMLObject Sphere

[KeithSloan]

Okay corrected - my silly mistake in test file.

Is this any better with refactored GDMLSphere?

Are you wanting to create one shape from all the spheres?
What format do you need for the other physics.

Have also exported to step if that helps?

testShell.zip

[bxyzhu]

Hi Keith,

Thanks for the quick replies. I checked the latest files you provided and it looks like exactly what I wanted. Yes, the idea here was to create a composite sphere with different thicknesses at different solid angles and eventually exporting to a STEP file for other tools (eg: FASTRAD).

I have not tried to install the makeConeFix branch (I've only installed using the AddOn Manager). Will the branch be merged soon so that it can be installed using the AddOn Manager or do you recommend to try to manually install the branch?

[KeithSloan]

As you already have the GDML workbench installed you should in a Command Line window be able to go to the FreeCAD.....Mod directory (location depends on OS and install)

From the Mod directory

cd GDNL
git fetch origin
git checkout makeConeFix

Restart FreeCAD.

I need to do some checks and will try to merge Friday, if you can wait.

[KeithSloan]

Okay we have a test suite at https://github.com/KeithSloan/FreeCAD_GDML_Test_Collection.

Just ran calcCenterOfMass.py on the testShell flie

12:45:29  testShell            Volume:  2043.73 cm^3 --> center of "mass": (   0.11,  -0.13,  -0.00) mm, moments of inetria: ( 3.341,  3.342,  3.341) x10^4 cm^5
12:45:29  Al_shielding_1_vol   Volume:    53.20 mm^3 --> center of "mass": (   4.79,   1.56,  -0.00) mm, moments of inetria: (0.8975,  2.037,  1.500) x10^3 mm^5
12:45:29  Al_shielding_2_vol   Volume:    98.52 mm^3 --> center of "mass": (   4.90,   4.32,  -0.00) mm, moments of inetria: ( 4.273,  4.849,  4.621) x10^3 mm^5
12:45:29  Al_shielding_3_vol   Volume:     1.08 cm^3 --> center of "mass": (   1.57,   7.04,  -0.00) mm, moments of inetria: (0.9100, 0.4032, 0.6730) cm^5
12:45:29  Al_shielding_4_vol   Volume:     1.59 cm^3 --> center of "mass": (  -5.89,   5.89,  -0.00) mm, moments of inetria: ( 1.273,  1.273,  1.307) cm^5
12:45:29  Al_shielding_5_vol   Volume:     2.51 cm^3 --> center of "mass": (  -8.32,  -2.42,   0.00) mm, moments of inetria: ( 1.505,  3.077,  2.345) cm^5
12:45:29  Al_shielding_6_vol   Volume:     1.38 cm^3 --> center of "mass": (  -4.64,  -9.11,  -0.00) mm, moments of inetria: ( 2.089,  1.152,  1.645) cm^5
12:45:29  Al_shielding_7_vol   Volume:   278.26 mm^3 --> center of "mass": (  -2.50, -11.16,  -0.00) mm, moments of inetria: (0.5944, 0.2217, 0.4122) cm^5
12:45:29  Al_shielding_8_vol   Volume:     3.26 cm^3 --> center of "mass": (   1.48, -11.72,  -0.00) mm, moments of inetria: ( 7.584,  2.776,  5.289) cm^5
12:45:29  Al_shielding_9_vol   Volume:    11.62 cm^3 --> center of "mass": (  11.91,  -7.56,  -0.00) mm, moments of inetria: ( 2.380,  3.381,  2.918) x10^1 cm^5
12:45:29  
12:45:29  Total                Volume:  2065.60 cm^3 --> center of "mass": (   0.16,  -0.19,  -0.00) mm, moments of inetria: ( 3.345,  3.346,  3.345) x10^4 cm^5

[KeithSloan]

load_gdml_color testShell.gdml -printCM

***** geometry moments ****
World Logical Volume: testShell
Al_shielding_1_vol_PV Volume: 53.20 mm^3 --> center of "mass": ( 4.79, 1.56, -0.00) mm, moments of inertia: ( 0.941, 2.085, 1.512) x10^3 mm^5 Entity type: G4Sphere
Al_shielding_2_vol_PV Volume: 98.52 mm^3 --> center of "mass": ( 4.91, 4.33, -0.03) mm, moments of inertia: ( 4.338, 4.916, 4.647) x10^3 mm^5 Entity type: G4Sphere
Al_shielding_3_vol_PV Volume: 1.08 cm^3 --> center of "mass": ( 1.58, 7.04, -0.00) mm, moments of inertia: ( 0.941,0.4321,0.6865) cm^5 Entity type: G4Sphere
Al_shielding_4_vol_PV Volume: 1.59 cm^3 --> center of "mass": ( -5.89, 5.90, -0.00) mm, moments of inertia: ( 1.33, 1.329, 1.333) cm^5 Entity type: G4Sphere
Al_shielding_5_vol_PV Volume: 2.51 cm^3 --> center of "mass": ( -8.31, -2.42, 0.00) mm, moments of inertia: ( 1.605, 3.174, 2.388) cm^5 Entity type: G4Sphere
Al_shielding_6_vol_PV Volume: 1.38 cm^3 --> center of "mass": ( -4.64, -9.11, 0.00) mm, moments of inertia: ( 2.132, 1.189, 1.655) cm^5 Entity type: G4Sphere
Al_shielding_7_vol_PV Volume: 278.26 mm^3 --> center of "mass": ( -2.49, -11.16, 0.01) mm, moments of inertia: (0.6006, 0.227,0.4131) cm^5 Entity type: G4Sphere
Al_shielding_8_vol_PV Volume: 3.26 cm^3 --> center of "mass": ( 1.48, -11.72, -0.01) mm, moments of inertia: ( 7.781, 2.931, 5.351) cm^5 Entity type: G4Sphere
Al_shielding_9_vol_PV Volume: 11.62 cm^3 --> center of "mass": ( 11.91, -7.54, -0.01) mm, moments of inertia: ( 2.438, 3.445, 2.939) x10^1 cm^5 Entity type: G4Sphere

Total Volume: 21.87 cm^3 --> center of "mass": ( 4.95, -5.95, -0.00) mm, moments of inertia: ( 3.882, 4.38, 4.128) x10^1 cm^5
***** geometry moments ****

So FreeCAD and Geant4 agree on Volumes.

[KeithSloan]

Refactored GDMLSphere merged to Main.