Very confused trying to run GRIP on Ubuntu

System: Ubuntu 16.04 64 bit
Develop Tool: Eclipse Oxygen

So I am trying to use GRIP to help develop vision processing
for the upcoming season. We are going to use a Raspberry Pi
for the vision processing and provide coordinates to the RoboRio
via Network Tables.

I am using an Ubuntu system to develop the code, the camera
is connected to it. Once we have the code fairly developed I
will then port it to the Raspberry Pi.

Using the example from: Off Board Vision Processing in Java
from the wpilib.screenstepslive.com site I tried to compile
the main.java program for the Ubuntu system.

I downloaded OpenCV-3.3.1, built it, and pointed to it as a “User Libraries”
in the “Build Path”.

I then ran into the ntcore error.

I downloaded ntcore-master ran the command:
./gradlew -PskipAthena -PreleaseBuild build

I now have a “build” directory, with stuff all over, what do I do with that and
what do I point to in Eclipse.

Finally, and I know this was a long email, but I am learning
I have these Imports, how can I verify upfront that they are available?

import java.util.ArrayList;

import edu.wpi.first.wpilibj.networktables.;
import edu.wpi.first.wpilibj.tables.
;
import edu.wpi.cscore.*;
import org.opencv.core.Mat;
import org.opencv.imgproc.Imgproc;

And the
System.loadLibrary(“opencv_java331”)
How can I verify the location of that ?

Thank you to all in advance.