Hi,
For he warning, you may increase RGBD/OptimizeMaxError (default 3) if you feel that it is rejecting too much good loop closures.
For the colors, you can mouse over the label over the images on left to see the legend:
![](http://official-rtab-map-forum.206.s1.nabble.com/file/n7888/Screenshot_from_2021-05-03_22-09-54.jpg)
![](http://official-rtab-map-forum.206.s1.nabble.com/file/n7888/Screenshot_from_2021-05-03_22-10-20.jpg)
For the link colors on graph view, right click and go in "Set link color...":
![](http://official-rtab-map-forum.206.s1.nabble.com/file/n7888/Screenshot_from_2021-05-03_22-09-12.jpg)
cheers,
Mathieu