Week 12-13 Realsense D435 on Ubuntu 18.04 and Range Flow Constrain
1. Realsense D435 ubuntu 18.04
Since some time has passed since the last time I research in to this topic and the JdeRobot platform is moving to Ros Melodic I research the possibility to move to Ros Melodic as well. The realsense-ros package is not out yet for easy installation on ros melodic. There is no plan to release it shortly due to the possibility of installing the packages from ros-kinetic from source code. Check this out here -> https://github.com/IntelRealSense/realsense-ros/issues/386
So I check the lastest version of the intel realsense SDK that the realsense-ros package supports and install it: (Using the official instructions from -> https://github.com/IntelRealSense/realsense-ros#installation-instructions))
(Intel realsense SDK) librealsense v2.25.0 -> https://github.com/IntelRealSense/librealsense/releases ros-melodic-desktop-full -> http://wiki.ros.org/melodic/Installation/Ubuntu (Ros realsense Wrapper) realsense-ros v.2.2.8 -> https://github.com/IntelRealSense/realsense-ros/releases
I had a problem while building from source the ros-realsense 2.2.8 since it has a dependency on: ddynamic_reconfigure-0.2.2
This package also has to be installed before realsense-ros https://github.com/ros/dynamic_reconfigure (not sure where I get the ddynamic reconfigure version…, if the problem arises when building just search that error on the internet until you get to a github issue)
After all it seems like the realsense-ros wrapper is working on Ubuntu 18.04 on ros-melodic
2. Range Flow Constrain
The objective was to understand and implement the range flow constrain algorithm. Read again Direct Depth SLAM version. Not enought information to understand the algorithm.
Since the Range flow equations that Ive seen, seems similar to those in the optical flow I research a bit about the optical flow to refresh my mind.
Image motion Constraint Equation http://www.cim.mcgill.ca/~langer/546/8-imagemotion-2-notes.pdf
The first 3 pages let me remember the optical flow, the optical flow constraint equation and a way to solve it.
Evaluating the Range Flow Motion Constraint by Hagen Spies, John L. Barron https://www.researchgate.net/publication/3974178_Evaluating_the_range_flow_motion_constraint
This talks about the range flow shortly. Once again I couldnt fully understand the algorithm but now Im sure that range flow is the same concept that optical flow but is applied to range images or range data (depth images). Ive just have to know how it can be applied to range data and implement it.
Range Flow Estimation by Hagen Spies, Bernd jahne and John L. Barron (Currently reading)