Importing and visualizing gdml with tessellated solids

Newbie
#1

Hi all,
I am new to root and am trying to importing a gdml with triangulated solids using TGeoManager. I get the following errors:

Error in TGeoVolume::SortNodes: Bounding box not valid
Error in TGeoVolume::Voxelize: Bounding box not valid
Error in TGeoVolume::FindOverlaps: Bounding box not valid

While inspecting, I found that TGeoTessellated had 0 vertices and 0 facets, however the name of the solid is read correctly. In TBrowser, I do see the solid in the tree but I cannot draw. Root crashes on trying to draw.

In a 2017 post ( Errors importing GDML tessellated solid with ROOT ) in this forum, I saw that tessellated solids were not supported, but I do not see the same error in the latest root. I want to confirm if root supports reading and visualization of tessellated solids now.

Any help will be highly appreciated.

Thank you.

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_ROOT Version:master
_Platform:macos
Compiler: Not Provided

#2

Nevermind. My gdml did not have “type” attribute.

#3

Hi all,

I run into the same issue as mentioned before:

Info in <TGeoManager::CheckGeometry>: Fixing runtime shapes...
Info in <TGeoManager::CheckGeometry>: ...Nothing to fix
Info in <TGeoManager::CloseGeometry>: Counting nodes...
Info in <TGeoManager::Voxelize>: Voxelizing...
Error in <TGeoVolume::SortNodes>: Bounding box not valid
Error in <TGeoVolume::Voxelize>: Bounding box not valid
Error in <TGeoVolume::FindOverlaps>: Bounding box not valid
Info in <TGeoManager::CloseGeometry>: Building cache...

What exactly is meant by “type” attribute in the GDML file?

I use an CAD based STL file as input for a G4 geometry and then use the G4 GDML export to create a GDML file to later import it into ROOT and convert it into a ROOT geometry:

G4:

auto mesh = CADMesh::TessellatedMesh::FromSTL(_cadFile);
...
G4GDMLParser outputParser;
outputParser.Write((outputFileName + ".gdml").c_str(), exportWorld);

ROOT:

TGeoManager* myGeo = new TGeoManager();
myGeo->Import(outputFile);

I tested it with a “simple” cube object - no difference.
Also exporting / importing it with G4 works without any issues.

#4

Hi all,

problem is understood:

In the GDML file:

<tessellated aunit="deg" lunit="mm" name="TestCube0x5ba10b0">
    <triangular vertex1="TestCube_v0" vertex2="TestCube_v1" vertex3="TestCube_v2" type="XXXX"/>
</tessellated>

the type attribute is not set when exporting the geometry via G4 (V 10.5.0) - only the vertexX attributes are present.
Adding the type attribute solves the issue.

#5

Geant4 and root do not implement the same set of gdml solids.

Root does not have tessellated solids or triangular surface elements.

#6

It does… The issue is fixed on the master: PR#6353

#7

Okay but what are we supposed to put in type? Just XXXX?

#8

As far as I remember correctly after two years it was either „relative“ or „absolute“ as definition for the values. But it should be fixed in the mention PR and the recent ROOT version >6.2X.

Nevertheless, keep in mind that tessellated objects are not used as material etc in the ROOT geometry and do not contribute to any particle interactions. At least that’s my latest information.

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