asset write produces a huge ply file

[TanakitkornK]

I've tried running Cartographer on the demo bag file (3D backpack):

wget -P ~/Downloads https://storage.googleapis.com/cartographer-public-data/bags/backpack_3d/with_intensities/b3-2016-04-05-14-14-00.bag roslaunch cartographer_ros demo_backpack_3d.launch bag_filename:=${HOME}/Downloads/b3-2016-04-05-14-14-00.bag

I am also able to save the pbstream file using the commands:

rosservice call /finish_trajectory 0 rosservice call /write_state "{filename: '${HOME}/Downloads/b3-2016-04-05-14-14-00.bag.pbstream', include_unfinished_submaps: "true"}"

However, when I tried using the asset writer I get a really huge ply file (over 20Gb). The command is as follows:

roslaunch cartographer_ros assets_writer_backpack_3d.launch bag_filenames:=${HOME}/Downloads/b3-2016-04-05-14-14-00.bag pose_graph_filename:=${HOME}/Downloads/b3-2016-04-05-14-14-00.bag.pbstream

Then I tried to open that huge ply file with CloudCompare but it freeze and crash every time. I suspect that the map size was too large. Is this big ply file is a typical output from assets_writer_backpack_3d.launch? How to open this huge .ply then? Or, is it possible to produce a less dense ply file?