Depth image not changing

[Void12987]

Preliminary Checks

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• This issue is not a question, feature request, or anything other than a bug report directly related to this project.

Description

Installing Zed on Foxy works for every topic except depth data and point cloud data. This might be a duplicate of #81, but not sure.

Steps to Reproduce

1. Install zed_ros_wrapper as per the README instructions
2. ros2 run image_transport republish compressed --ros-args -r in/compressed:=image_compressed -r out:=image_raw
3. ros2 launch zed_wrapper zed2.launch.py

Expected Result

ros2 topic echo /zed2/zed_node/depth/depth_registered has changing data

Actual Result

it's the same black image

ZED Camera model

ZED2

Environment

OS: Ubuntu 20.04
CPU: x86_64
GPU Nvidia 1060
ZED SDK: 3.7
ROS Foxy

Anything else?

1. If the republish node is necessary to get the data, should it be on the README?
2. If it's not necessary, what could be the reason why no data (even normal image data) can be retrieved in ROS?

[Myzhar]

Hi @Void12987
image_transport is faulty in ROS2 Foxy.
It's a known problem:
https://github.com/stereolabs/zed-ros2-wrapper#image-transport-plugins-and-compressed-topics

[Void12987]

Hi @Myzhar,

Although I removed the image_transport packages, is there anything I can do to get depth data working? I'm confused because I followed the README and saw your depth demo on LinkedIn, so I might be missing something.

[Myzhar]

I just followed the instructions step by step to be sure that everything works as expected and that nothing is missing:

$ ros2 topic hz /zed2/zed_node/depth/depth_registered
average rate: 15.002
	min: 0.065s max: 0.068s std dev: 0.00054s window: 17
average rate: 14.531
	min: 0.065s max: 0.133s std dev: 0.01177s window: 31
average rate: 14.361
	min: 0.065s max: 0.133s std dev: 0.01372s window: 45
average rate: 14.273
	min: 0.065s max: 0.133s std dev: 0.01448s window: 59
average rate: 14.414
	min: 0.065s max: 0.133s std dev: 0.01300s window: 74

Be sure to install the correct image_transport package v3.0.0 as described here:
https://github.com/stereolabs/zed-ros2-wrapper#image-transport-and-topic-subscriptions

[Void12987]

Yes ros2 topic hz works fine, but does your ros2 topic echo have changing data?

[Myzhar]

Looking at the data in ros2 topic echo is not a good way to debug and understand if this kind of topic is correctly published.

- 255
- 255
- 127
- '...'
---

this means that not all the data are displayed for obvious reasons. Furthermore, you are trying to read floating-point values from a vector of uint8_t values...

if you want to be sure that the depth map is changing you can use instead the rqt viewer by selecting PlugIns -> Visualization -> Image View

If you have not installed rqt:

sudo apt install ros-foxy-rqt-*

[Void12987]

I can confirm I locally built image_common-3.0.0.

Below is a screenshot of using depth quality NEURAL mode, but the image is black.

Interestingly, when I try to run depthimage_to_laserscan, zed_wrapper throws an error about the depth and rgb are async.

When I run depth quality at PERFORMANCE mode, then the depth data shows up, but it's a bit choppy, not working in certain lighting conditions

Maybe my GPU is too old?

[Myzhar]

Have you optimized the NEURAL AI model by running the command
ZED_Diagnostic -ais 8
before starting the ZED node?

[Void12987]

Thanks so much for helping; it's working now.

I thought I'd add some suggestions on updating the README; if you'd like me to open a PR, let me know and I'll do it:

1. mention to optimize using ZED_Diagnostic
2. In the installation prompts, it says cudnn is only necessary for object detection, but now that it's required for the default mode for depth detection; it could mention that too, because previously I didn't have cudnn installed
3. It wasn't clear to me that the v3.0.0 was necessary because afterwards it says to install the latest version, which didn't work, maybe we could erase that part?

Anyways thanks for the help. I hope to be creating a robotics marketplace soon for free advertisement of robotics products, and the ZED camera is the best for that!

[Myzhar]

Do not hesitate to suggest README modifications.
User feedback is always the best way to improve our tools and software.

[Void12987]

Cool, although I don't know how to update the instructions on the install script, I will open a PR for updating this README at some point next week.

UPDATE: I'm not on the project that involves ZED anymore, so I likely won't have time for this now, but good luck on the project.