Attention: Answers.ros.org is deprecated as of August the 11th, 2023. Please visit robotics.stackexchange.com to ask a new question. This site will remain online in read-only mode during the transition and into the foreseeable future. Selected questions and answers have been migrated, and redirects have been put in place to direct users to the corresponding questions on Robotics Stack Exchange. Additional details are available here.
Actually not, gmapping occupancy grip map has only 3 states: occupied, free and busy.
Cartographer's states are about 100 based on certainty, so it needs to be transformed.