Point cloud integration

[nesnes]

Now the wrapper is able to provide the 3D point cloud, the depth map and the camera images at the same time. There is only one zed.launch now, the wrapper automatically adapts on subscribers change.

[Myzhar]

I was thinking about using CUDA to remap Depth Mat to pointcloud.
The loop at
https://github.com/nesnes/zed-ros-wrapper/blob/master/src/zed_wrapper_node.cpp#L122
is really heavy, don't you think that CUDA can give better performances?

Furthermore Depth and RGB information are available in GPU memory, so you have not bottleneck...

[eric-wieser]

Could you not have squashed these commits a little?

[eric-wieser]

Why did this change remove windows support?

[eric-wieser]

continue is not ok here - you've now left one of the entries in point_cloud.points with unitialized memory, which is impossible for anything downsteam to detect.

[nesnes]

Yes, that's what we can think, but when you read the std::vector::resize documentation, you see that if no default object is given to the resize as second arg, the default constructor is use the create the new objects. So the continue is possible because all the points in the cloud are initialized by the resize.

http://www.cplusplus.com/reference/vector/vector/resize/

[eric-wieser]

Presumably the default constructor for this type is zero-filled? Isn't NaN more desirable for a missing data point

[nesnes]

This is a logic that should be handled by the PointCloud object itself and it will be a bad idea to try to overwrite it. You can see in rviz that the "missing" points aren't displayed, so the information is already in the message.

[eric-wieser]

Ok, there's definitely a bug here due to the multithreading. This worked just fine with the std::thread constructor replaced with a direct function call.

I think the issue is a concurrent interaction like this:

thread1: camera->grab();
thread1: float buffer = camera->retrieveMeasure(...).data
thread2:          do_something_with(*buffer)
thread2:          do_something_with(*buffer)
thread1: camera->grab();
thread2:          do_something_with(*buffer); // either this causes a segfault
thread1: camera->retrieveImage();
thread2:          do_something_with(*buffer); // or this does