TGeo ->Draw() strange behaviour

ROOT
1

Hi,

I am currently preparing a detector geometry and have a problem to draw the geometry. The detector consists of several sub-detectors and each sub-detector of several layers.The full geometry is stored in a .root file. My problem is, that I can Draw() the whole detector (including my sub-detector) and single layers of my sub-detector, but when I try to Draw() my sub-detector completely, only an empty Canvas shows up. I tried already to check and uncheck all options and I am now really desperate. The other sub-detectors can be drawn separately without any problems. Do you have any idea what could be the reason for this behavior?

Thanks in advance,
Christian

2

Can you attach your geometry and tell me what are you trying to see ?
Cheers,

3

Hi,

please find attached the geometry file. I would like to draw ‘PXD’, but only
‘PXD_Layer_1’, ‘PXD_Layer_2’, or further daughter volumes can be drawn.
I have no idea what’s wrong.

Cheers, Christian
test.root (18.4 KB)

4

Well, your geometry is too deep for the default visible level (3). Use something like:

Some things may be a bit outdated, but you can find this one among other useful details in the user documentation.

Cheers,

5

Hi,

thank you so much!!! However, I think there is some bug or feature: Before I had a TGeoVolumeAssembly of a TGeoVolumeAssembly of a TGeoVolumeAssembly (I know this is bad for performance!). I changed now the last container to a TGeoVolume and no more problems to show the geometry! It also worked fine to show the whole detector together with other subdetectors…

Christian

6

Hi,
You are right about assemblies: use them only when you actually need them. But related to visualization: a volume assembly has no real shape - you can only visualize its content, i.e. one level down. If the content is made again of assemblies, you go again down to visualize, until you find a REAL volume to display… The visualization uses the so called visible level, but it may happen that at that level you have no volume to display. So yes, this is a feature, you just have to understand how it works.

There is an option however to compute automatically a visible depth for you - this is not used by default and gets disabled if you use SetVisLevel(). You can call gGeoManager->SetMaxVisNodes(10000) (or some other number) that will try to compute the depth so that the number of displayed objects do not exceed the request. Try that - it may help.

Cheers,