CODEWITHSUNDEEP
ubunturos
Moetz Mohamed
Moetz Mohamed

Reputation: 23

error while extracting images from a ROS bag

i have been working on a localization via image processing localization project and the data sets we got was a compressed images in a .bag files so i have multiple ways to extract these images at first i tried the following method:

mkdir images
cd ./images
rosrun image_view extract_images _sec_per_frame:=0.01 image:=<IMAGETOPICINBAGFILE>
run rosbag play <BAGFILE>

and i have tried to use the launch file as well

<launch>
   <node pkg="rosbag" type="play" name="rosbag" args="-d 2 /home/devo/datasets/Ch2_002/HMB_1.bag"/>
   <node name="extract" pkg="image_view" type="extract_images" respawn="false" output="screen" cwd="ROS_HOME" args="compressed">
   <remap from="image" to="/camera/image_raw"/>
   <param name="image_transport" value="compressed"/>
   </node>
</launch>

but it always ended up giving me the same error

[ERROR] [1486685243.634766995]: Client [/extract_images_1486684806987962257] wants topic /can_bus_dbw/can_rx to have datatype/md5sum [sensor_msgs/Image/060021388200f6f0f447d0fcd9c64743], but our version has [dataspeed_can_msgs/CanMessageStamped/33747cb98e223cafb806d7e94cb4071f]. Dropping connection.

so i just wanted to know what did i do wrong and how can i extract these images from the bag (knowing that my ROS version : 1.12.6)

Upvotes: 2

Views: 3630

Answers (1)

Vtik
Vtik

Reputation: 3150

try the folowing :

1- In a writable directory : 

$ rosrun image_view extract_images image:=<IMAGETOPICINBAGFILE> _image_transport:=compressed

2 - In another terminal, play your bag file

this should save your images in that directory.

Now, if that doesen't work, are you sure that your image_transport compressed is true ? cause the error means that the publisher and subscriber on the same topic have different message types. This also might happen if you bag is created using a different platform with a different message definitions other than the one you'r playing it on.

Edit :

Another way around is to decompress data and then save it. It goes like this : 

$rosrun image_transport republish compressed in:=<IMAGETOPICINBAGFILE> raw out:=image/raw

$rosrun image_view image_saver image:=image/raw _save_all_image:=all _filename_format:=%04d.%s

$ rosbag play <bagfile>

Hope that helps !

Upvotes: 0

Related Questions