topic Re: ROS - Measure distance with D435 in Items with no label

ROS - Measure distance with D435

FAl — Wed, 24 Jan 2018 12:22:24 GMT

Hello,

I installed librealsense 2.8.1 and the ROS wrapper 2.0.1. When i'm using the realsense-viewer I can view the depth and color streams. I am also able to measure the distance in the viewer.

How can I measure the distance with a ROS node?

I tried the sample code posted here : https://github.com/IntelRealSense/librealsense/tree/development# quick-start GitHub - IntelRealSense/librealsense at development but it dosen't work.

The sample code uses the rs_pipeline. Is it possible to subscribe to the depth topic and calculate the distance from it? If I rostopic echo the depth stream the resulting values range between 0 and 255 (not the distance in m).

Thank you

Re: ROS - Measure distance with D435

FAl — Wed, 24 Jan 2018 14:43:22 GMT

// License: Apache 2.0. See LICENSE file in root directory.

# include

void chatterCallback(const sensor_msgs::Image::ConstPtr& msg)

{

cv_bridge::CvImagePtr Dest = cv_bridge::toCvCopy(msg);

ROS_INFO("Width: %i", msg->width);

ROS_INFO("Height: %i", msg->height);

ROS_INFO("Value: %f", Dest->image.at(msg->width/2,msg->height/2));

}

int main(int argc, char **argv)

{

ros::init(argc, argv, "distance");

ros::NodeHandle n;

ros::AsyncSpinner spinner(1);

spinner.start();

ros::Subscriber sub = n.subscribe("camera/depth/image_raw", 100, chatterCallback);

ros::Duration(100).sleep(

return 0;

}

I wrote this node. I subscribe to the depth stream and the output of width and height of the depth stream are correct.

The distance value still doesn't work. It always returns 0.00.

Is my conversion from ROS to OpenCV correct?

Re: ROS - Measure distance with D435

idata — Wed, 24 Jan 2018 23:21:22 GMT

Hello FelixAl,

We escalated your question to RealSense developers. We'll let you know as soon as we have an answer.

Regards,

Jesus

Intel Customer Support

Re: ROS - Measure distance with D435

idata — Fri, 26 Jan 2018 00:29:12 GMT

Hello FelixAl, we received this code snippet from the dev team that will do as you asked.

Hi,

The following code snippet can do what he asked. I added a ROS conversion from raw depth pixel to a distance in meters.

# include <ros/ros.h>

# include <image_transport/image_transport.h>

# include <cv_bridge/cv_bridge.h>

# include <sensor_msgs/image_encodings.h>

# include <iostream>

# include <depth_image_proc/depth_conversions.h>

# include <depth_image_proc/depth_traits.h>

void chatterCallback(const sensor_msgs::Image::ConstPtr& msg)

{

cv_bridge::CvImagePtr Dest = cv_bridge::toCvCopy(msg);

ROS_INFO("Width: %i", msg->width);

ROS_INFO("Height: %i",<span style="color: ...

Re: ROS - Measure distance with D435

FAl — Fri, 26 Jan 2018 09:48:45 GMT

Thank you! It works.

Regards,

Felix