This is something of a confusing double negative.  To me, setting "DONT_COLLAPSE" to false suggests that collapsing will happen.  I'd just use "false" here, since the meaning is clear from the parameter name.  The name of "COLLAPSE_EMPTY_TREE" is a little misleading, too; setting it to true suggests that trees will always be collapsed (and if that were true, why pass it as a parameter?)  In fact, that constant only applies when processing the bitstream, so perhaps something like COLLAPSE_EMPTY_TREES_BITSTREAM would be clearer--or better yet, remove it from the header file and make it a constant in the definition of processRemoveVoxelBitstream.