chukcha2's profile - activity

Thank you for answering my question. I think that a feature that allows specifying the maximum interpolation "distance"

Hello, I have a question about tf interpolation. if I understand it correctly, tf will interpolate when it is asked for a transform between two published transform values. So If I published tf1 for time 5 and tf2 for time 10 and then ask for transform for time 7, I am going to be returned a transform that is somewhere in between tf2 and tf3.

Question: can I ask tf not to interpolate if the requested timestamp is too far away from a known transform? For example in my example above, can I ask tf to interpolate only if I am within 1s from a given transform. So for example above if I ask for transform at time 7 I don't get anything but if I ask for a transform at time 5.5 or 4.5 I do get it?

Or is there a way to find out what two transforms (along with their timestamps) the interpolation was made?

Let's assume we only have a single link. I ask tf for a transform for time t and it returns it to me. Is there a way to

tf interpolation Hello, I have a question about tf interpolation. if I understand it correctly, tf will interpolate whe

Did adding a sleep as Jack suggested caused ROS messages to be reliably printed? I tried sleeping for 1 second and still

Were you able to find a more suitable driver or is this what you end up using? If so, can you share how you adapted it for Spatial (Dual?) INS?

The but_velodyne wiki states that the package has been tested only with Velodyne HDL-32E. I am wondering if anyone has tried using the package with VLP16 or is aware of a reason why it would not work with VLP16?

I am looking for ways to colorize point cloud generated by VLP16 and am starting to investigate if but_calibration_camera_velodyne can do that. Has anyone used this node to colorize point clouds? What were the results?

According to ROS Documentation Publisher and Subscriber queue_size argument controls the queue message size for publishers and subscribers. It also says that if a queue gets fulls, oldest messages will be dropped. Is there a way to find out when messages are dropped? Is there a way to know how full are the queues are?

FYI. I asked this question explicitly here

Thank you. So is this roughly what happens then?:

msg --publish()--> q1 --roscpp--> q2  --unknown --> **tcp/ip stack**  --> q3 -- subscriber callback --> msg

q1 size is unlimited (dangerous?), q2 size is controlled by advertise()'s queue_size, q3 controlled by subscriber's queue_size.

To me it sounds like the doc (wrongly) says that queue_size parameter in advertise() controls the "second set of queues" that you call q2 (the one the message is moved to by internal roscpp thread). I think it should say that the parameter controls the size of the queue that publish() pushes onto.

Thanks @janindu. So the doc quoted above is wrong/misleading.

I read ROS Documentation:

publish() in roscpp is asynchronous, and only does work if there are subscribers connected on that topic. publish() itself is meant to be very fast, so it does as little work as possible:

1. Serialize the message to a buffer
2. Pushes that buffer onto a queue for later processing

The queue it's pushed onto is then serviced as soon as possible by one of roscpp's internal threads, where it gets put onto a queue for each connected subscriber -- this second set of queues are the ones whose size is set with the queue_size parameter in advertise(). If one of these queues fills up the oldest message will be dropped before adding the next message to the queue.

From the above I understand that the publisher pushes messages onto q1 and the subscriber retrieves data from q2. Data transfer from q1->q2 is taken care of by the roscpp internals. The documentation seems to suggest that advertise()'s queue_size option controls the size of q2 (not q1). Is that right? If that is really the case, then what controls the size of q1? And what queue does subscriber's queue_size control?

Am I misunderstanding the quoted text from documentation, or does it really say that queue_size parameter in advertise() sets the size of q2. I expected that is would set the size of q1. I'd expect that q2 size would be set by subscribe()'s queue_size parameter. What am I missing?

hi Raph, I am need to do solve the same problem (colorize point clouds from images / match 3d points and pixels). Do you have any pointers/suggestions for me? Thank you.

I need to scan and get an accurate 3D model of a small building and its surroundings (trees, etc.). I plan on mounting my sensors on a small drone and fly around the building to scan it. The resolution should be good enough to see details like pipes, chimneys, conduits, etc. My main question is whether rtabmap can be used to achieve it. My second questions is what is the best sensor setup to use with rtabmap to achieve this goal. I have a 3D LiDAR unit (Velodyne VLP-16). Can it be used by RTAB to produce a 3D model? Do I need any additional sensors and why? I can use velodyne_pointcloud node to get sensor_msgs/PointCloud2 point clouds from the lidar. Can rtabmap be used to produce an accurate 3D model from them? Any insight is greatly appreciated. Thank you.

I am looking into doing something similar. Except I am using Velodyne VLP16 LiDAR. The laser point cloud and the image have different sizes. Do you have any pointers on how to calibration camera and LiDAR in such setup?

Sorry @Kailegh, I am not using the package, but you can ask questions here: https://github.com/laboshinl/loam_vel...

@Icehawk101, how do you use a range finder for measuring altitude? And yes, it would be great to see the maps you were able to generate.

Hello, Does hector_slam create only 2D maps or can it be used to created 3D models as well? My data comes from a Velodyne LiDAR and I need to create a 3D model of the object that is being scanned. I am looking for the right tool to use and was not sure if hector_slam could create 3D models. If it can't and you can recommend something else, please do so :) Thank you.

@ateator, if possible, can you keep this correspondence public so that others can benefit from it too? ;) @hashim, did you use an IMU in your setup?