# voxl_mpa_to_ros2 only publishes left stereo camera

Source: https://forum.modalai.com/topic/4577/voxl_mpa_to_ros2-only-publishes-left-stereo-camera
Category: VOXL SDK and Software (https://forum.modalai.com/category/47/voxl-sdk-and-software)
Tags: ros
Posted: 2025-07-08 23:16:26 UTC by cguzikowski
Replies: 4 · Views: 2982

## cguzikowski · 2025-07-08 23:16:26 UTC

Hello, I am currently trying to use stereo cameras (m0015) within a custom ROS2 application using the voxl_mpa_to_ros2 (version 0.0.6) package on the VOXL2 (SDK 1.4.0), but I am only able to see left stereo camera when running the mpa to ros converter. Here is the output of ros2 topic list:
```
/imu_apps
/parameter_events
/rosout
/stereo
/stereo_disparity
/stereo_disparity_scaled
/stereo_pc
/voa_pc_out
/vvhub_aligned_vio
/vvhub_body_wrt_fixed
/vvhub_body_wrt_local
```
According to the docs, I should expect something along the lines of `/stereo/left` and `/stereo/right`. Recording the topic `/stereo` and then playing it back confirms that only the left camera is being recorded. Here is the output of `/etc/modalai/voxl-camera-server.conf`, which was created by running `voxl-configure-cameras 10`
```
{
	"version":	0.1,
	"fsync_en":	false,
	"fsync_gpio":	109,
	"cameras":	[{
			"type":	"ov7251",
			"name":	"stereo",
			"enabled":	true,
			"camera_id":	0,
			"camera_id_second":	1,
			"independent_exposure":	false,
			"fps":	30,
			"en_rotate":	false,
			"en_rotate_second":	false,
			"en_preview":	true,
			"preview_width":	640,
			"preview_height":	480,
			"en_raw_preview":	true,
			"ae_mode":	"lme_msv",
			"gain_min":	54,
			"gain_max":	8000,
			"ae_desired_msv":	60,
			"exposure_min_us":	20,
			"exposure_max_us":	33000,
			"exposure_soft_min_us":	5000,
			"ae_filter_alpha":	0.600000023841858,
			"ae_ignore_fraction":	0.20000000298023224,
			"ae_slope":	0.05000000074505806,
			"ae_exposure_period":	1,
			"ae_gain_period":	1
		}]
}
```
Both cameras are fully functional when viewing from the portal.

How can I get data from both of the cameras?

## Reply by teddy.zaremba · 2025-07-11 19:13:38 UTC

Hi @cguzikowski,

I'm not getting that issue when I have them connected on separate ports, is that an option for you? 

There might be a bug in mpa-to-ros2 when using COMBO_MODE, but I'll need more time to check that out.

## Reply by teddy.zaremba · 2025-07-11 20:28:22 UTC

@cguzikowski 

So there's no bug in mpa-to-ros2. I agree this is a little confusing so maybe we need to change it, but at the moment when you connect two cameras with COMBO_MODE the data shows up in the same pipe. 

This means that the ROS topic "/stereo" will have both of the images stacked on top of each other, so for the time being you'll have to write some code to separate the two.

## Reply by cguzikowski · 2025-07-14 19:21:32 UTC (in reply to teddy.zaremba)

@teddy-zaremba Unfortunately we can't connect them to separate ports. I recorded a bag on the topic "/stereo" and playing the bag back I only see one of the images. All messages are mono8 of size 480x640, so I don't see how they could be stacked on each other. Do I need to separate the images before recording?

## Reply by cguzikowski · 2025-07-14 21:17:08 UTC (in reply to teddy.zaremba)

@teddy-zaremba Nevermind, I was able to separate the images by modifying the voxl-camera-server.conf file to treat each camera as separate and it seems to be working now