MichaelHsu170's profile - activity

I'm just wondering when could the problem be fixed?

I'm running a 32-bit Ubuntu 11.10, and the installation of ros-electric-desktop-full always ends up with the following error.

xxx@ubuntu:~$ sudo apt-get install ros-electric-desktop-full
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies: ros-electric-desktop-full : Depends: ros-electric-vision-opencv (= 1.6.7-s1320939105~oneiric) but it is not going to be installed
Depends: ros-electric-image-pipeline (= 1.6.3-s1320939324~oneiric) but it is not going to be installed Depends: ros-electric-image-transport-plugins (= 1.4.2-s1320939218~oneiric) but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

Installation of ros-electric-vision-opencv ends up with the following

xxx@ubuntu:~$ sudo apt-get install ros-electric-vision-opencv
Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies: ros-electric-vision-opencv : Depends: libopencv2.3-dev (= 2.3.1+svn6514+branch23-7~oneiric) but 2.3.1+svn6514+branch23-8~oneiric is to be installed
E: Unable to correct problems, you have held broken packages.

xxx@ubuntu:~$ uname -a
Linux ubuntu 3.0.0-12-generic #20-Ubuntu SMP Fri Oct 7 14:50:42 UTC 2011 i686 i686 i386 GNU/Linux

How could I compile opencv programs outside ROS?

I installed the opencv-2.3.1 package through ROS, but there seems to be link errors when compiling opencv programs outside ROS.

I created a Makefile file with the following content

DisplayImage:DisplayImage.cpp
    @g++ -L/usr/lib/ `pkg-config opencv-2.3.1 --cflags --libs` -o DisplayImage DisplayImage.cpp

But the compiling result is

XXX@ubuntu:~/Documents/programs/OpenCV$ make
/usr/bin/ld: cannot find -l/usr/lib/libopencv_contrib.so.2.3.1
/usr/bin/ld: cannot find -l/usr/lib/libopencv_legacy.so.2.3.1
/usr/bin/ld: cannot find -l/usr/lib/libopencv_objdetect.so.2.3.1
/usr/bin/ld: cannot find -l/usr/lib/libopencv_calib3d.so.2.3.1
/usr/bin/ld: cannot find -l/usr/lib/libopencv_features2d.so.2.3.1
/usr/bin/ld: cannot find -l/usr/lib/libopencv_video.so.2.3.1
/usr/bin/ld: cannot find -l/usr/lib/libopencv_highgui.so.2.3.1
/usr/bin/ld: cannot find -l/usr/lib/libopencv_ml.so.2.3.1
/usr/bin/ld: cannot find -l/usr/lib/libopencv_imgproc.so.2.3.1
/usr/bin/ld: cannot find -l/usr/lib/libopencv_flann.so.2.3.1
/usr/bin/ld: cannot find -l/usr/lib/libopencv_core.so.2.3.1
collect2: ld returned 1 exit status
make: * [DisplayImage] Error 1

pkg-config --libs --cflags opencv-2.3.1

shows

-I/usr/include/opencv-2.3.1/opencv -I/usr/include/opencv-2.3.1 -l/usr/lib/libopencv_contrib.so.2.3.1 -l/usr/lib/libopencv_legacy.so.2.3.1 -l/usr/lib/libopencv_objdetect.so.2.3.1 -l/usr/lib/libopencv_calib3d.so.2.3.1 -l/usr/lib/libopencv_features2d.so.2.3.1 -l/usr/lib/libopencv_video.so.2.3.1 -l/usr/lib/libopencv_highgui.so.2.3.1 -l/usr/lib/libopencv_ml.so.2.3.1 -l/usr/lib/libopencv_imgproc.so.2.3.1 -l/usr/lib/libopencv_flann.so.2.3.1 -l/usr/lib/libopencv_core.so.2.3.1

How could I fix the problem? Thank you.

Hi, These are just msgs in a structured way so that they can be published or subscribed by a node. They are just values. It depends on the node which actually uses them to manipulate robot. It depends on how you want to use it. For example in teleop_base package the teleop_base_keyboard.cpp takes the msgs from keyboard and uses them as m/sec. If your node takes this msgs as mm/sec then the node execution will be accordingly.

You can know the msg types by the following command.

rosmsg show geometry_msgs/Twist

whose output is

geometry_msgs/Vector3 linear
  float64 x
  float64 y
  float64 z
geometry_msgs/Vector3 angular
  float64 x
  float64 y
  float64 z

Hope this helps, Karthik

Are there any instructions about the meaning of geometry_msgs/Twist elements? e.g. What's the unit of linear and angular, m/s? degree/min? degree/s?

Here is a list of supported cameras in ROS. Additionally, there exist camera drivers for other types of camera. For example, my company uses the Axis 214 PTZ camera. It's a network camera with pan/tilt/zoom and also with audio capabilities. It provides 704x576 maximum resolution at 60 fps. It also comes with its own programming API to control the pan-tilt-zoom. Drivers can be found here.

EDIT: All Axis cameras provide a control API known as Vapix. This is a HTTP-based programming library. You essentially send web-scripts to the HTTP server that's running on the camera. The camera then returns a message that expresses success or failure, etc. To program with ROS, you'd need to convert ROS commands to simple Vapix messages, send them over UDP, and then parse the response into ROS-readable format. I think the Axis 214 uses Vapix 2.0, but I'm not entirely sure. Google will tell you for sure.

As for mounting the Kinect on the camera, I don't see a reason that you couldn't do that. It would certainly look interesting to say the least. You'd just have to be careful to leave room for the camera to rotate properly, but that shouldn't be difficult.

Hi guys, I'm working on a research on robot vision with a robot platform of Pioneer 2DX run in ROS. Would you like to introduce me some models of pan tilt zoom camera priced around $1500? My OS is Ubuntu 11.10. Thanks.