Paulo's profile - activity

Hello,

I'm a student and I'm working with ROS and gazebo for simulation. I'm using this package (https://github.com/Sahloul/ar_sys) that uses Aruco Markers and gives poses of the Arucos.

I started with Gazebo and I was getting really high error in the detected Arucos Marker poses, now that I'm working with actual robots and with Kinects and I get almost no error in the measurements of the Aruco poses. They are almost perfect, like 1 degrees of error, comparing to the almost ~10 degree error in the Gazebo simulator.

In Gazebo I used a simulated camera 1980x1082 and in real life I only have a Kinect that is 640x480.

I also added a little bit of noise to the simulated camera in Gazebo.

Who can I justify this differences in the results? I was expecting real life situation to be worst then in Gazebo.

Thx so much for the help! Gazebo is amazing.

Hello,

I need to do a grid shearch to caracherize the error of the camera I'm working with in gazebo.

For that I need to add white noise to the camera.

In the URDF I see that Gazebo already does that.

    <noise>
      <type>gaussian</type>
      <!-- Noise is sampled independently per pixel on each frame.
           That pixel's noise value is added to each of its color
           channels, which at that point lie in the range [0,1]. -->
      <mean>0.0</mean>
      <stddev>0.007</stddev>
    </noise>

Are there any instructions or something I can read to know more about how I should tune this 2 parameters? Any examples/tutorials here is Gazebo?

I hope Gazebo doesn't use just rand() function to generate this white noise. It doesn't right?

The ideia I have is to leave the mean at zero and just increase the stddev, but to what number?

Thx for help.

It worked thx. I was confused sorry.

I did that and I got a bigger image. But does that change the size of the pixels? I don't want to change the size of the image I want to change the size of the pixels. I want better resolution by having smaller pixels

Hello,

how do you change the pixel size of a URDF camera?

I follow the tutorial in Gazebo but it doesn't say how to do this.

Thx so much friends.

I used the tutorials to make a differential robot in Gazebo with a camera. I want to use this robot with ROS. I thought I could simply describe the robot using SDL but now that I reached the Connect with ROS and in the first part it says I need to start with a URDF description of the robot.

I think in the first tutorials(Build Robot) there should be some warning to people, that they should start by creating their robots in URDF if they want to use them with ROS.

thx you. I copied the model I needed and it works now.

In this tutorial when I insert my_robot I get a grey screen from Gazebo, and in the console it says "Waiting for model database update to complete".

Then says "Unable to connect to model database...".After this starts giving errors. Is there anyway I can simply download the model of the Hokuyo sensor? Why is this even connecting to some database? There is something really wrong with this tutorial.