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2014-04-20 06:47:20 -0500 | marked best answer | Converting Kinect RGB image to OpenCV gives wrong colours Hey everyone I have been playing a bit with the kinect camera using the openni driver. When running openni_node.launch and viewing the rgb image using rviz, then everything looks perfect, but when I create a node that has to the purpose to read the rgb image, convert it to a cv image and displaying it using imshow, then the colours are all wrong. Red is blue, blue is red, green is something yellow and yellow is light blue. I have been trying to use RGB8 and BGR8 encodings, but nether of them shows any difference. A sample of my code is shown below, inspired from the example in the cv_bridge tutorial: Does anyone know what might cause this problem? I am using the newest version of Diamondback. Regards Sebastian Aslund |
2014-04-20 06:47:16 -0500 | marked best answer | roscd pointing to wrong folder Hey everyone Earlier today I tried to install the OpenNI driver according to the tutorial on the ROS homepage link, but the result turned my ROS installation into a total mess. The driver was unable to install due to some part of openCV missing, but I was unable to install them since roscd suddenly pointed to the ros/unstable folder instead of ros/cturtle. I tried to remove ROS and install it again hoping that would help, but seems the path is defined in some bash file, but I have no clue where or how to change it back so my ROS works again. Furthermore, then during the installation of the new ROS I got a few messages like this one "sh: getcwd() failed: No such file or directory", is it also caused by his failure in roscd or some other problem, never experienced this message during the installation of ROS through the repository. Last but not least, it is not possible to install the OpenNI driver without involving creating the unstable folder? Since it seems that it creates more harm than good. Thanks for your help Sebastian Aslund |
2014-01-28 17:27:04 -0500 | marked best answer | How does the local planner determine when the goal is reached? Hey everyone I have a maybe simple question, how does the local planner described in the navigation tutorial determine when the goal is reached?
My question arises due to my testing of the local planner. I have 5 goals/offices in an simulated environment with odometry noise. Move_base tells whether the goal have been reached successfully but I also want the pose. So after each goal have been reached I publish the pose estimated by AMCL. I can see it fits very well with the xy goal tolerance but some times it is off by 1-3cm which it not much but I still find it very strange. The move_base should not confirm a succeeded reached goal if it is 1-3cm outside the defined tolerance. It have made me question how the local planner actually determines when a goal is reached but I can not find any detailed documentation on this and I hope someone here can help.
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2014-01-28 17:26:55 -0500 | marked best answer | Problems with TF using the navigation stack Hey everyone To better understand my question I will provide some background information. I am running a mobile robot in Stage (simulation). The "problem" with this approach is that my odometry information is ideal and I want some error introduced to evaluate the navigation stack. I have therefore created a node which sends out a frame called "odom_error" which represents the erroneous odometry. Here x, y and phi is my deviation. There is thereby a link between the frames "odom_error" and "odom", but somehow the navigation stack is unable to detect this shown in the image below. I tell the AMCL node to use odom_error as source for odometry information, but when doing so the costmaps are unable to detect the connection between /map and /base_link. I get the following error: |
2014-01-28 17:26:37 -0500 | marked best answer | Improve gmapping results Hey everyone I am working with the ROS Navigation stack using a simulated environment in Stage. Initially I would have created a topic criticizing the precision of the AMCL localization stack, but after deeper research I found the error to occur from the map I have created with the GMapping.
I have also tried to visualize quite primitively how I have traveled through the area. The black dot is the start and the numbers shows the order in which the different areas have been explored.
Does anyone have any idea to how to improve the result of the GMapping process? So far it does not seem that impressive. Regards P.s my laser scanner is modeled to a SICK LMS200 with a range at 8m. |
2014-01-28 17:26:13 -0500 | marked best answer | Deprecated Kinect driver superior to the new one Hey everyone I have been working for a project for a couple of months now which includes cup detection using the Kinect camera. After the release of Fuerte I upgraded my machines accordingly, but apparently I forgot the machine running my Kinect camera. The first image is taken with the deprecated driver and the second with the new one. While the scaling is a bit different, it is purely due to zoom. The position of the camera is fixed and the cups have not been moved. |
2014-01-28 17:25:17 -0500 | marked best answer | Linking problems between two packages Hey everyone I have a very strange problem. I am working on creating an interface to a Katana arm by Neuronics. There have already been made one here http://www.ros.org/wiki/katana, but it is way to bloated and user defined for my purpose. So what I did was to extract the core package for the katana arm. This is actually just a ROS wrapper to the original interface API created by Neuronics. What the wrapper does is compiling the API and setup export paths in the manifest file: Afterwards I created my own package which included the katana API wrapper package in its manifest file. This gave me seamlessly access to the API's include file and everything compiled nicely until today. Not matter what I try will the linking of my interface e.g. return the following error: I have tried so many things, but what worked a few days ago seems to lead to nothing now. I have tried making everything from scratch, but with the same result. Another point to make is that I am running ROS Fuerte with the newest updates. Could it be these updates that causes the error or is there a totally different reason why linking the wrapper to my interface fails? Regards Sebastian Aslund |
2014-01-28 17:22:26 -0500 | marked best answer | Love Arch Linux, but won't behave with ROS Hey everyone I recently moved to Arch Linux after getting tired of Ubuntu due to its rigid structure and I absolutely love it, but the last couple of days have I worked with installing ROS. This have not be an pleasant journey and I am currently stucked at a problem I have been unable to figure out. I get the following three line error message:
I hope someone have an idea how to solve it. Regards Sebastian Aslund |
2014-01-28 17:22:20 -0500 | marked best answer | Calibrating Kinect with surroundings Hey everyone I am having a serious problem with my Kinect project, but since many are working with the Kinect camera, then I hope someone have solved this or atleast have an idea how to solve it. My Kinect camera is able to find a suitable grasping point, but is done according to the optical frame of the Kinect camera. In order to use it with a robot arm, then I need to know how the base of the robot arm is located according to the camera. I have tried to use markers on the robots end-effector and combine it with the knowledge of the forward kinematic, but apparently there is some serious errors with the markers (ArToolKitPlus), which means the distance on the z-axis is several centimeters off. In am not entirely sure why, but atleast I am looking for an alternative method to calibrate the Kinect camera with the environment and I hope someone have some ideas Regards |
2014-01-28 17:22:16 -0500 | marked best answer | OpenNI camera parameters gives faulty marker detection Hey everyone Following my problem with getting the camera parameters from the OpenNi driver which is now solved, then I have set up ArToolKitPlus to detect markers using the RGB camera with the parameters from "rgb/camera_info". I have previously used the ArToolKitPlus in another project where it worked fine, but this time I experienced some problems with the distance in the z-axis. I have used rviz to compare the frame of the marker with the RGB point cloud, the marker frame has "openni_rgb_optical_frame". Screenshots of this is can be seen here and here, there square marker might be a bit hard to see, but it looks like the found marker fits regarding the x- and y-position, but the depth is totally off. The question is why the depth is failing using ArToolKitPlus, I am have also tried to do manual calibration of the camera and getting more or less the same parameters, so the problem must be something internal in the Kinect camera. Maybe something originating from the depth sensing? I hope someone has an idea to solve this problem as marker detection is crucial for two of my projects. Regards Sebastian Aslund |
2014-01-28 17:21:54 -0500 | marked best answer | Kinect and PCL Hey everyone I am currently working on a project where I have a pile of cloth and kinect camera mounted above this pile looking down on it. The aim is then to find a grasping point using the kinect camera so a robot arm is able to grasp a piece of cloth. My initial idea was to use the depth information to find the deviation between different pixels, an area with high deviation will then correspond to a piece of cloth sticking out. A good example could be this image where the folds will give a high deviation and thus a good grasping point. A thing I have noticed during my research is the widely use of pointclouds and the PCL library with the Kinect camera, and therefore I wonder about using the pointclouds to find the deviation. My problem is that I cant find a good indeep tutorial how to use the PCL library and I wonder if someone has some good links or explanation how to process pointcloids with the PCL library. |
2014-01-28 17:21:53 -0500 | marked best answer | Getting all parameter names using C++ I am developing an application where I need to get all the parameter names from the parameter server (without specifically knowing the names of each parameter). I have only seen it possible on python using "getParamNames(caller_id)", but is something similar possible using C++? |
2014-01-28 17:21:44 -0500 | marked best answer | Getting the calibration parameters of the Kinect camera Hey everyone I am working with the Kinect camera and plan to include some marker detection using ArToolKitPlus, but it requires that I provide a calibration file and my question is how I get these information from the Kinect camera. Inside the openni_camera folder under a subfolder info there are some calibration files present, but I am not sure whether the information stored in these file are usable. ArToolKitPlus uses these parameters. Regards Sebastian |