Dear Sir/Madam,
I did some programming with realsense R200 camera. It's a project that measures distance from camera to wall using depth camera and compare the result with Aruco method for RGB camera.
For your requirement, the phase1 and getting nearest obstacles is phase 2 is no problem. However, the 360 degree detect using 4 camera is impossible. Because the maximum view angle of camera is about 70 degree.
If your obtacles are fixed, you could use only 1 camera then rotate your vehicle a small angle then go straight a small distance to keep fixed distance (1 m) with detected obtacles.
About your development environment, I'd like to know on what OS should I use, Ubuntu or Windows, Could you provide specific version, e.g. Ubuntu 16.04. The Realsense driver and SDK is different for every OS and version.
By the way, is your vehicle is a drone? I'm very interested in it and have a small quadrotor.
I'm hoping to have a change to work with you.
Thanks & Best Regards,
Khanh