TH3 and the label size on colour palette


I have a TH3 histogram which I draw as:


and then I try to resize the labels on the colour palette using the standard procedure:

TPaletteAxis pal_1 = (TPaletteAxis)hist_power_1->GetListOfFunctions()->FindObject(“palette”);

But it does not work. I get:

root [0]
Processing glvox_W.C…

*** Break *** segmentation violation
Generating stack trace…
0x0000000111e1a499 in
0x000000011031b27a in cling::IncrementalExecutor::executeFunction(llvm::StringRef, cling::Value*) (in + 1130
0x00000001103233ad in cling::Interpreter::RunFunction(clang::FunctionDecl const*, cling::Value*) (in + 157
0x000000011032291e in cling::Interpreter::EvaluateInternal(std::__1::basic_string<char, std::__1::char_traits, std::__1::allocator > const&, cling::CompilationOptions const&, cling::Value*, cling::Transaction**
0x0000000110322ef6 in cling::Interpreter::echo(std::__1::basic_string<char, std::__1::char_traits, std::__1::allocator > const&, cling::Value*) (in + 38
0x0000000110358025 in cling::MetaSema::actOnxCommand(llvm::StringRef, llvm::StringRef, cling::Value*) (in + 549
0x0000000110351b15 in cling::MetaParser::isXCommand(cling::MetaSema::ActionResult&, cling::Value*) (in + 1077
0x00000001103511b1 in cling::MetaParser::isCommand(cling::MetaSema::ActionResult&, cling::Value*) (in + 97
0x0000000110350fba in cling::MetaParser::isMetaCommand(cling::MetaSema::ActionResult&, cling::Value*) (in + 42
0x0000000110355ea7 in cling::MetaProcessor::process(char const*, cling::Interpreter::CompilationResult&, cling::Value*) (in + 231
0x000000011026f30e in TCling::ProcessLine(char const*, TInterpreter::EErrorCode*) (in + 2382
0x0000000110271f49 in TCling::ProcessLineSynch(char const*, TInterpreter::EErrorCode*) (in + 121
0x000000010fe75980 in TApplication::ExecuteFile(char const*, int*, bool) (in + 2352
0x000000010fe7493c in TApplication::ProcessLine(char const*, bool, int*) (in + 1500
0x00000001101c5720 in TRint::ProcessLineNr(char const*, char const*, int*) (in + 112
0x00000001101c54c0 in TRint::Run(bool) (in + 976
0x000000010fe10e8f in main (in root.exe) + 79
0x00007fff8ba365fd in start (in libdyld.dylib) + 1
0x0000000000000003 in
Root >

I am using ROOT6 on a MacOSX 10.9.

Is it possible to change the colour palette labels for a TH3 histogram?

Thank you,


With the GL option the palette is not the same as the one without. It is part of the plot
You cannot really act on it.


I see. Thank you for your reply. Then I am still wondering, knowing that it is not possible to change the label sizes in the palette with the GL option, if it could be possible to make them be a bigger size BEFORE drawing the histogram with the “glcolz” option? Something like gStyle->SetLabelsSize() or something similar.

The reason I ask is that I want to put the plot in a paper, and the labels on the colour palette are not easily readable, so I want to make them bigger… I am sure someone else must have had this problem before I did.

Many thanks,


I just look at the code. A TGAxis axis is created in DrawPaletteAxis in TGLPlotPainter.cxx.
But not external settings are applied to this axis.