julled's profile - activity

Hey domhege, thank you for your answer! You can see a new EDIT at the question. gruß aus Berlin

Anyone got a idea? I think the problem is frames / tf related but i cant find the error... view_frames output: http://i.imgur.com/VvhjkBf.png

Anyone got a idea? I think its frame / tf related but i cant find my error. view_frames output: http://i.imgur.com/VvhjkBf.png

Thank you Isaac! I am running 1.8.17 rviz. Do you think it could be a frame related problem like tfoote thinks?

Im not sure if i get the other question right, but you mean who does the transform from world to kinect? In Vrep its: simExtROS_enablePublisher('tf',1,simros_strmcmd_get_transform,kinect_visionSensor,kinect,'') simExtROS_enablePublisher('tf',1,simros_strmcmd_get_transform,kinect,-1 ,'') -1 is /world

Thank you tfoote for your answer! view_frames output: http://i.imgur.com/VvhjkBf.png The rostopic echo of /scan reveals that the frameid is /kinect

Hi everyone, im pretty new to ROS and i still haven't understand every bit of it. So there are still some things which are a bit strange to me. And i want to say sorry in advance for not writing the best english..

What i want to do: Im trying to use a simulated Kinect in VREP as source for a SLAM-Algorithm in ROS.

Systemconfig: I use Fuerte on a Ubuntu 12.04 LTS

Progress: I transfered the Kinect Pointcloud to ROS via a Topic and used the pointcloud_to_laserscan/CloudToScan nodelet to convert it to a fake-laserscan with the following script:

<launch>

 <!-- openni_manager -->
  <node pkg="nodelet" type="nodelet" name="openni_manager" output="screen" respawn="true" args="manager"/>

  <!-- throttling -->
  <node pkg="nodelet" type="nodelet" name="pointcloud_throttle" args="load pointcloud_to_laserscan/CloudThrottle openni_manager">
    <param name="max_rate" value="20"/>
    <remap from="cloud_in" to="/vrep/KinectPointCloud"/>
    <remap from="cloud_out" to="/cloud_throttled"/>
  </node>

  <!-- fake laser -->
  <node pkg="nodelet" type="nodelet" name="kinect_laser" args="load pointcloud_to_laserscan/CloudToScan openni_manager">
    <param name="output_frame_id" value="/kinect"/> <!-- Question1 -->
    <param name="min_height" value="-0.025"/>
    <param name="max_height" value="0.025"/>
    <remap from="cloud" to="/cloud_throttled"/>
  </node>
</launch>

But if i want to show the laserscan in rviz something strange happens to the pointcloud: (i put some decay on the laserscan to see multiple scans at once)

(thank you for the upvote, now i can post the picture)

It seems as the points arent mapped to the "real world". They are "rotating" with the Robot (Kinect). Shouldnt they normally stay at the objectpositions? I really think that the problem is tf-related... The tf-Tree is visible in the rviz screenshot. The /scan Topic (laserscantopic) is transformed via

rosrun tf static_transform_publisher  0 0 0 0 0 0 kinect_visionSensor scan 100

tf echo puts out:

---
transforms: 
  - 
    header: 
      seq: 0
      stamp: 
        secs: 1399584596
        nsecs: 289725537
      frame_id: /kinect
    child_frame_id: /kinect_visionSensor
    transform: 
      translation: 
        x: -0.0141000151634
        y: 0.0292500853539
        z: 0.0323894619942
      rotation: 
        x: 3.98174461205e-08
        y: 0.707106751384
        z: 0.707106810989
        w: -5.22563454972e-08
---
transforms: 
  - 
    header: 
      seq: 0
      stamp: 
        secs: 1399584596
        nsecs: 289725537
      frame_id: /world
    child_frame_id: /kinect
    transform: 
      translation: 
        x: 0.20544680953
        y: -0.454404950142
        z: 0.345994025469
      rotation: 
        x: 4.20090261606e-05
        y: 2.69500965001e-05
        z: -0.479030467743
        w: 0.877798273228
---
transforms: 
  - 
    header: 
      seq: 0
      stamp: 
        secs: 1399584596
        nsecs: 477231988
      frame_id: /kinect_visionSensor
    child_frame_id: /scan
    transform: 
      translation: 
        x: 0.0
        y: 0.0
        z: 0.0
      rotation: 
        x: 0.0
        y: 0.0
        z: 0.0
        w: 1.0
---

After that Messages there are multiple tf-messages just like the last one. After a few seconds the other two get a update.

Questions:

1. Im not shure what the "output_frame_id" in the script should be. What should i put there?
2. Is my tf-tree okey? Im really not that sure about that.
3. fixed Frame = "/world" is ok for rviz?
4. Do i need more tf-data from VREP?

I think i missed one little piece in the huge ros-puzzle... ?