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Hi Everybody.
I wonder how RVIZ can display a 2d probabilistic map.
I have a 2D matrix where I store the probabilistic values of an occupancy grid map. What can I use to display this values in RVIZ?
Regards,
The rviz map plugin unfortunately currently only supports the three discrete states unknown, occupied and free. See this code snipped from visualization/rviz/src/rviz/default_plugin/map_display.cpp (starting at line 289):
for( unsigned int pixel_index = 0; pixel_index < num_pixels_to_copy; pixel_index++ )
{
unsigned char val;
if(msg->data[ pixel_index ] == 100)
val = 0;
else if(msg->data[ pixel_index ] == 0)
val = 255;
else
val = 127;
pixels[ pixel_index ] = val;
}
It is thus currently not possible to use nav_msgs/OccupancyGrid.msg messages and display more than these 3 states/color values in rviz. However, one could use the existing map_display plugin as a starting point for a modified version that displays more levels of grey. Only changing the above loop would be necessary for that (if you want to keep using standard nav_msgs/OccupancyGrid messages).
probabilities are in the range [0,100], which means the occupancy grid values dont have to take discrete states. You can have a an occupancy value of 90 ie a probability of 0.9. Therefore you can use occupancy grid msg to render probability maps. Everything will just be in gray scale
ROS costmaps are typically visualized using nav_msgs/GridCells. If you were to fill one of these data structures with your probabilistic map, you would be able to visualize it in Rviz in three colors (INFLATED, OCCUPIED, UNKNOWN).
What I did to visualize probabilistic maps, however, was simply to save my data structure as an image file (with OpenCV) and then view it as a sensor_msgs/Image. This is a pretty hacky solution, but I needed to save them as images anyway, so it worked for me.
EDIT:
To convert my costmap-like data structure to an OpenCV image, I simply just set each costmap cell as a pixel in an OpenCv IplImage data structure. Then, you can just cv_bridge to convert that image to a sensor_msgs/Image. This is simple to do if you know OpenCv, but you might have to do some research on the OpenCv image data structure. It's not too complex.
It should be noted that the Image in Rviz is in a separate window from the robot body. You won't be able to overlay one on the other using this method.
Asked: 2012-02-06 21:49:15 -0500
Seen: 5,498 times
Last updated: Feb 08 '12
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