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brightness of uvc_camera on Hydro armhf

asked 2014-06-25 10:26:10 -0500

hvn gravatar image

Hi,

Although uvc_camera works, the brightness settings are set to maximum and looking at https://github.com/ktossell/camera_um... this is hardcoded. So my question is if/how I can change this without (much) hassle ? I don't have a calibration xml file, and doubt using one will overrule the cpp settings. Right now I have to work in semi-darkness to get some nice images.

Thanks.

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answered 2014-06-26 12:31:51 -0500

Ken gravatar image

I've removed the hardcoded values. New .deb packages should be available soon. If you are using a USB Video Class camera, you could try http://wiki.ros.org/libuvc_camera , which has more parameter support and usually delivers new images more quickly.

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Thank you for this. After running it successfully at first, I now find a problem: "uvc_open: Access denied (-3)". Apart from chmod o+rw /dev/video0, I didn't change any settings. What may be the cause of this ?

hvn gravatar imagehvn ( 2014-06-30 09:23:17 -0500 )edit

You must not have write access to /dev/bus/usb/[BUS#]/[DEV#]. Have you set up any udev files as in http://wiki.ros.org/libuvc_camera#Permissions ? If you previously gave yourself permission using, e.g., `chmod a+rw /dev/bus/usb/BUS/DEV`, then that permission will be reset when you unplug the camera.

Ken gravatar imageKen ( 2014-06-30 09:47:07 -0500 )edit

libuvc doesn't use /dev/videoX -- it takes over the role of the Linux driver that normally creates /dev/video. In fact, when libuvc_camera is running, /dev/video0 should disappear.

Ken gravatar imageKen ( 2014-06-30 09:49:44 -0500 )edit

Had to restore the system and set up again. Now, setting the permissions on /dev/bus was the issue. Will that permission be set automatically? I didnt set it when I ran it the first time but it did work.

hvn gravatar imagehvn ( 2014-06-30 10:22:04 -0500 )edit
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answered 2014-06-25 16:18:29 -0500

oyvinaak gravatar image

Hi!

I have a solution, but it might not be what you want. We need a camera in our robot project to recognize different shapes etc. To do this, we use SimpleCV. This will give you easy access to the camera and the default configuration is pretty sweet. I didn't have to do anything to get a pretty nice image (I need to increase the resolution a bit though). So what you can do, is to use SimpleCV to interface your camera, and then convert those images to ROS images and publish them to a topic. It works flawlessly and is easy to integrate with your ROS project.

Øyvind

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Thanks for your response. Looking at its website, it says it's a Python equivalent to OpenCV. Right now, I'm extensively using OpenCV so I doubt this is the right solution for me.

hvn gravatar imagehvn ( 2014-06-26 02:12:19 -0500 )edit
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answered 2014-06-26 10:41:10 -0500

Eric Perko gravatar image

There appears to be a fork of uvc_camera that adds some additional parameters. See https://github.com/ktossell/camera_um...

It's unclear what the status of that pull request is though.

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Asked: 2014-06-25 10:26:10 -0500

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Last updated: Jun 26 '14