Why is there a 0.5 coefficient for trajectory critics scoring?

[willxxx0909]

double getScale() const override {return costmap_->getResolution() * 0.5 * scale_;}

In the getScale() function of map_grid.cpp, I understand the getResolution() * scale_ for mapping the score into map frame with a scale num, but why is it multiplied with a 0.5?

[DLu]

Reference

The short answer is that the scales for the dwb_critics were tuned to match dwa_local_planner, but digging through that code, I can't immediately find the reason for the 0.5.