# Questions tagged [geometry]

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### How can I construct a semi-circle in urdf

Making a cylinder is easy. How can I make a semi-circle shape?
18 views

### Which data structure/library to handle set of points within distance bounds from target?

I have a problem where I have to position a camera (mounted on a robot manipulator) at an optimal location from a 3D target defined as a (convex) polyhedron. The camera must maintain a minimum ...
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### Transform PointCloud2 doesn't work as expected

I tried to transform my pointcloud2 in python like stated here. But somehow the result is not correct. I am not able to visualize the pointcloud I get as a result in rviz. This is why I tried to just ...
375 views

### Do I need to use Inverse Kinematics if I have the coordinates of all joints?

So I have the positions of all the joints (x,y,z) of a robot arm. I need to calculate the angles of the joints to feed them to another similar robot arm. I cannot get the angles from the robot I need ...
164 views

### Efficient sphere surface area search

As shown in the figure, there are objects of arbitrary shapes placed on the surface of the sphere at arbitrary locations. The problem is to search the surface to locate these objects in most efficient ...
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1 vote
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### How to get RPY(Roll, Pitch, Yaw) from directional cosines from a single vector?

I'm trying to find the pose of an 3D vector in terms of RPY. Let's say the two end points of the vector is P0(x0, y0, z0) and P1(x1, y1, z1). So the centered vector I get is V(Vx, Vy, Vz) = P1 - P0 = (...
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### unable to build geometry package in ROS kinetic

Im trying to install geometry package but im getting this error: ...
1 vote
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### Representation of 2D coordinate space with orientation

I wanted to know what is the mathematical representation of 2D coordinate space with orientation in the same plane. 2D coordinate space is represented as $R^{2}$, how do I include orientation in the ...
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### tf2_eigen include does not find library Eigen/Geometry

Hi, I want to use tf2_eigen to convert geometry_msgs/Vector3 messages (and further ...
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### Vısual sensor.camera lenses with a field of view of more than 180 degree

What kind of camera models can be used for lenses with a field of view of more than 180 degree ? Is ıt possible if not why? Are fisheye lenses suitable for this purpose?
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Hi folks, I have been following the book Programming Robots with ROS and have been struggling with how the origin tag means in URDF files. In the chapter 18, there is a snippet of URDF as the ...
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### Image coordinate to robot coordinate

I am working with a Nao robot. One if the things I want to do is the following: Take an image of geometrical objects in front of the Nao (done) Extract features from the objects in the image, such as ...
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### how to Transform Pointcloud2 with tf

Hi, I tried to run the python code on this link http://answers.ros.org/question/9103/how-to-transform-pointcloud2-with-tf/ and got such an error below : Traceback(most recent call last): File "/...
1 vote
89 views

### Which Trajectory representation for optimization

I'm strugling on that problem for a while, so any help is welcome. I need a trajectory representation that is performant for optimization, i.e. I want something that computes quickly. The function I ...
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### Recognizing a line from three r-theta ultrasonic distance readings?

Anyone know of sample Python code, or a tutorial, on the polar coordinate math for recognizing that three ultrasonic distance readings form a straight line? ...
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### Consitent Scale in Monocular pose estimation

I just wanted to know if scale is conserved across multiple images, when doing a process such as monocular odometry. I know in reality the scale tends to drift over time due to accumulation of small ...
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### 6 axis robot arm with non-perpendicular axes?

Lately I've been thinking about 6 axis robots and noticed that all examples that I've seen on the internet use the same configuration of axes: Vertical axis waist (1), horizontal axis shoulder (2) ...
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### Which library can I access XmlRpcValue.h file?

Hello ROS users, While installing geometry package for tf, during catkin_make I receive error: 21%] Built target roscpp_generate_messages_cpp [ 21%] Built target roscpp_generate_messages_py [ 22%] ...
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### how to calculate transform for two geometry_msgs/poseStamped messages

Hi, I am new to ROS and RTT. I want to calculate the transformation (relative position) for two geometry_msgs/poseStamped messages so that I can get the absolute position of my object if the position ...
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### Fence avoidance for manually controlled robot

I'm trying to find known techniques for keeping a manually controlled robot within a known polygon fence. More specifically, a pilot controls a robot by issuing desired velocity vectors, and the ...
2k views

### Generalized Voronoi Diagram

I need to compute the Voronoi diagram for a map with some obstacles but I can't find any pseudo-code or example in MATLAB. The "voronoi" function in MATLAB works with points, but in this case the ...
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### Mobile robot algorithm implementation error

I am working in reproducing a robotics paper, first simulating it in MATLAB in order to implement it to a real robot afterwards. The robot's model is: $$\dot{x}=V(t)cos\theta$$ \dot{y}=V(t)sin\...
1 vote
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### How to determine the angles between a UAV and a sphere

I have an UAV modeled in three dimensions with let's say position coordinates $p_{uav} = (x_1,y_1,z_1)$ that is moving in a direction $d = (d_x,d_y,d_z)$ and a moving obstacle modeled as a sphere with ...
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### Most accurate rotation representation for small angles

Assume that I have a rigid body for which I know that it can rotate with respect to a global reference frame (which is considered fixed and already given) for only a few degrees of angle, so I can ...
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### URDF Mesh filetypes?

What are all the possible filetypes I can use in the , <mesh ... /> tag? I'm actually trying to use another URDF file as a mesh filetype, but it doesn't seem to be possible. Originally posted ...
247 views

### Angle to a circle tangent line

I want to simulate the detection of a moving object by a unicycle type robot. The robot is modelled with position (x,y) and direction theta as the three states. The obstacle is represented as a circle ...
1 vote
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### Which geo-projection to use for odometry [closed]

I would like to make a little survey regarding the (geo)spatial projection that you use when elaborating your GPS and movement data for the spatial awareness of your robots. Moving all GPS ...
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### 6D localization with 6 lasers

I have to know where a multi-rotor is, in a rectangular room, via 6 lasers, 2 on each axis. The problem is like this: Inputs : Room : square => 10 meters by 10 meters 6 positions of the lasers : ...
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### Relative orientation of two robots

Given two robot arms with TCP (Tool Center Point) coordinates in the world frame is: $X_1 = [1, 1, 1, \pi/2, \pi/2, -\pi/2]$ and $X_2 = [2, 1, 1, 0, -\pi/2, 0]$ The base of the robots is at: \$...
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### How to deal with an offset in precise GPS data?

I've got a robot setup with a very precise differential GPS (centimeter level). For technical reasons, I can't attach the GPS directly over the rotational center of the robot, but rather need to make ...
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### how to: geom calcs in ROS

I'm in the need to do geometry calculations (matrix_by_matrix, vector_by_matrix, scalar_by_vector, and so on). I looked up the documentation but the vector class isn't documented at all, and doing ...
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### Could not find tf/transform_listener.h

Hey there, I have a problem with the tf package. In my code I'm using the following includes: ...