joshvillbrandt/elp-stereo-camera-ros-pkg

Extracting correct data

Opened this issue · 3 comments

GnawXam commented

Hi,

I'm trying to use this camera to create a depth map. At first I thought I would need to do all the processing (getting the raw camera data, matching time stamps, finding correspondences) but I see that your package already sends out a lot of data to different topics. For the right camera:

/elp/right/camera_info
/elp/right/image_raw
/elp/right/image_raw/compressed
/elp/right/image_raw/compressed/parameter_descriptions
/elp/right/image_raw/compressed/parameter_updates
/elp/right/image_raw/compressedDepth
/elp/right/image_raw/compressedDepth/parameter_descriptions
/elp/right/image_raw/compressedDepth/parameter_updates
/elp/right/image_raw/theora
/elp/right/image_raw/theora/parameter_descriptions
/elp/right/image_raw/theora/parameter_updates

Could you briefly explain what these are and which one would be most helpful for me?
How does right / left camera each have a compressedDepth?

Somewhat related:
I looked into your code and it seems like "elp_stereo_camera.urdf.xacro" is the main program? But it seems so simple and I couldn't tell where/how you're publishing all these topics and how rviz is using the data.

Thank you for the help.

GnawXam commented

Hi,

So I can manage to read and display the "/elp/*/image_raw/compressed" but I cannot do the same with the "compressedDepth"

I get this warning when I try to echo "/elp/right/image_raw/compressedDepth"

Compressed Depth Image Transport - Compression requires single-channel 32bit-floating point or 16bit raw depth images (input format is: rgb8).

Waiting to see if you can explain what is being published to compressedDepth; or maybe I'm looking at the wrong topic?

joshvillbrandt commented

Hey, I'm probably not going to get a chance to look up the topics until Monday. Feel free to ping me again then.

Josh

Sent from my iPhone

On Jul 21, 2016, at 4:18 PM, GnawXam notifications@github.com wrote:

Hi,

So I can manage to read and display the "/elp/*/image_raw/compressed" but I cannot do the same with the "compressedDepth"

I get this warning when I try to echo "/elp/right/image_raw/compressedDepth"

Compressed Depth Image Transport - Compression requires single-channel 32bit-floating point or 16bit raw depth images (input format is: rgb8).

Waiting to see if you can explain what is being published to compressedDepth; or maybe I'm looking at the wrong topic?

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GnawXam commented

Hi,

I never managed to use compressedDepth; I'm not sure what it does, actually. If you can clear some stuff up that'd be great.

Anyways, I'm using OpenCV's imshow() and I can display the CompressedImages in grayscale.
The goal is to get a depth map; I think I may need to know the focal length, sensor pixel size, and distance between the 2 cameras. Did you have a spec on these values? I think I found one on the distance between the 2 cameras but I don't know the other information.

Anything would help.

Thanks.