answered Dec 9 '15
As I can see from source code, you can fill options for constructor AKAZEFeatures::AKAZEFeatures(const AKAZEOptions& options) and change its descriptor_pattern_size which is set by default to 10 ( see AKAZEConfig.h )
options
AKAZEFeatures::AKAZEFeatures(const AKAZEOptions& options)
descriptor_pattern_size