How to get the Depth Value in meters from a Astra Depth Camera

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Hi,

I am using a Astra depth camera and I have recorded few .bag files which are publishing depth datas on the topic /camera/depth/images.

I am able to view the depth video stream in RViz but I would like to have a c++ code where in I can subscribe to that topic and process it and get he depth values in Meters.

I tried this code but it doesn't give me any distance value.

Is there any way or any code to do this process. If so kindly let me know.

Thanks in advance.