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2014-01-28 17:29:43 -0500 | marked best answer | Extract values in DisparityImage I am trying to extract the values of certain points in a stereo_msgs::DisparityImage message. I'm assuming that the values are stored in "sensor_msgs/Image image" inside the DisparityImage message. So I did this: But all I got is a black and white image. Did I do something wrong, or am I just not approaching this correctly? |
2014-01-28 17:29:42 -0500 | marked best answer | TimeSynchronizer too slow for PointCloud2 and LaserScan. I used messaged_filters to sync messages from a pointcloud2 topic and and a laserscan topic, process, and publish it. But the publish rate is too slow for it to be of any use, even without doing anything in the processing bit. About 5-8 seconds for each published. Does anyone know any alternatives? |
2014-01-28 17:29:29 -0500 | marked best answer | opencv stereo correspondence "OpenCV Error: Bad argument (Unknown array type) in cvarrToMat" I'm trying to compute depth using stereo correspondence but keep getting the error in the title of this question. I don't really know how to debug this. Code: Unless my C++ is a lot rustier than I thought, I think I'm using the functions correctly. Which is why I don't see any problem with my code. It works fine without: and the function decleration is: Edit: I also tried from http://stackoverflow.com/questions/11027574/convert-cvmat-to-const-cvmat-or-cvmat: |
2014-01-28 17:29:28 -0500 | marked best answer | Subscribing to multiple topics of the same type. Is it possible to subscribe to multiple topics of the same type using a single callback function? If it's possible, I can't figure out how. Please and thank you. |
2014-01-28 17:29:28 -0500 | marked best answer | gmapping: base_link to odom missing The simulated robot I'm using does not define a transformation from \base_link to \odom. When I started Gazebo and load the robot, the top most node of the frames tree is the \base_link. When I run gmapping, \odom is automatically created with a \map parent, on a separate tree from the rest of the robot's frames. So I'm manually writing a transformation from \base_link to \odom. However, there's a nav_msgs::odometry topic published by the robot which I suspect is the odometry of the robot in the world frame. I can't figure out how to make use of that topic. Do I just read from it and broadcast the transform like in http://www.ros.org/wiki/navigation/Tutorials/RobotSetup/Odom? How would gmapping know which is the odometry frame? Is it the name? If it's the name then the \base_link frame of my robot isn't named "base_link". Is that a problem? On a related note, does the transformation from base_link to laser has to be direct? Or as long as a path on the tree exists, it's fine? |
2014-01-28 17:28:10 -0500 | marked best answer | Newbie Dependency Question First of all, I have to admit that I've only did the tutorials until ROS/Tutorials/UsingRxconsoleRoslaunch and then I jumped right into stage/Tutorials/SimulatingOneRobot. I'm trying to build the teleop_base package in the tutorial but I'm getting one dependency error which I'm not sure if I can ignore. After executing Okay so the package 'joy' which is missing is to interface a joystick, which I don't think I'd be using. It said "Built 15 package with 1 failures." Can I just proceed and ignore the failure since I don't need the the joy package anyways? How do I check if the 15 packages are built? If I just go into the manifest and remove the 'joy' dependency line, will ... (more) |
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2013-09-23 13:27:16 -0500 | marked best answer | error: ‘SurfFeatureDetector’ is not a member of ‘cv’ I'm trying to work out how to use OpenCV on ROS. I've gone through the cv_bridge tutorial and understand how to convert to the sensor_msgs::Image to the format used by OpenCV, in order to use the image with OpenCV libraries, and convert it back to sensor_msgs::Image. And by the cv::circle and cv::NamedWindow examples in the cv_bridge tutorial, I assumed that I can use the algorithms in the OpenCV documentation by referring to the cv namespace. So I decided to write a simple program to try out the feature detector algorithms in OpenCV, referring to http://docs.opencv.org/doc/tutorials/features2d/feature_detection/feature_detection.html. And got to this point: } But I got an error: It works with the cv::SurfFeatureDetector line commented out. I'm stuck at that point. I don't think I'm missing any headers. Any help? Please and thank you. |
2013-09-04 22:41:32 -0500 | marked best answer | Merging Multiple PointCloud2 Is there a way to merge two different PointCloud2 messages? Assuming they are defined in the same frame of course. |
2013-07-26 01:49:15 -0500 | marked best answer | Trying to install dependencies. Trying to install dependencies for http://www.ros.org/wiki/rgbdslam# (rgbdslam) following the instruction on the page: But I keep getting the error saying: Basically, it is missing the resources that it is suppose to install, like octomap. I've tried grabbing the missing resources manually, using rosws, but got stuck at octomap, where the error pops up even though octomap is already in the package path. So I decided to double back and try to investigate what I did or assumed wrong in the first place. Any help? |