Digital zoom

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shrubbery
Posts: 3
Joined: Tue Jul 07, 2020 6:51 am

Digital zoom

Post by shrubbery » Tue Jul 07, 2020 8:00 am

Hi all!

I am new to this forum, but I have used Zoneminder for some time. Recently I moved to the Docker Image maintained by dlandon (I know there is separate sub section int the forum, but my question is not docker related).

Now to my question for which I could not find anything helpful in the forum nor the web. It might well be that I have not done it correctly, but I have reached a point where I don’t know what to do next.

I have a HiLook IPC-T651H-Z camera which covers four zones. Motion detection works fine but the object detection does not generate results- I believe this is caused by the fact that object(s) to be detected are too far away or tiny. Is there a possibility to digitally zoom into the Zone before the object detection?

Any help would be much appreciated!
Thanks, and regards Nick

SteveGilvarry
Posts: 445
Joined: Sun Jun 29, 2014 1:12 pm
Location: Melbourne, AU

Re: Digital zoom

Post by SteveGilvarry » Tue Jul 07, 2020 4:21 pm

Not answering from any knowledge of your object detection, but the camera outputs its resolution and normally everything works with that. Digital Zoom is just the sensor being higher resolution than the screen so you can "zoom" but all you are doing is looking at same image just getting closer to 1:1 sensor to screen pixels. Equivalent to Actual Scale in ZM.
If the area of interest is far away best to go long focal length lens, but that reduces the field of view for the camera, so it is always a trade-off. Of course with that camera you could task it to zoom and track targets, not that anyone has written that yet for zm that I have seen. What does its region of interest function do?
Production Zoneminder 1.35.x
Random Selection of Cameras (Dahua and Hikvision)
More Dev VM's than I care to count.

shrubbery
Posts: 3
Joined: Tue Jul 07, 2020 6:51 am

Re: Digital zoom

Post by shrubbery » Wed Jul 08, 2020 7:02 pm

Hi Steve,

Maybe I have explained myself not well enough. I have a 3M picture. Objects which are close to the camera are obviously large and are mostly detected. However, if it comes to smaller objects e.g. cats walking across, they are never identified. The resolution and the quality of the picture is good enough to identify those objects. Is there a config in Yolo that allows to analyse the picture in a more accurate but maybe slower way?

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asker
Posts: 1413
Joined: Sun Mar 01, 2015 12:12 pm

Re: Digital zoom

Post by asker » Wed Jul 08, 2020 8:32 pm

Some thoughts:

1. Make sure you enable debug logs - when you see objects not being reported, study the logs to make sure they are not being discarded. As an example, if Yolo min confidence exceeds the confidence set, it will be rejected, but you will see it in logs.

2. There are settings in the config (yolov3/yolov4.cfg) file that might help. But you'll have to experiment, including potentially retraining yolo with updated config parameters to detect smaller pictures. Start here https://github.com/AlexeyAB/darknet/issues and search for "small objects" there are various tips/approaches
--
My collection of ZoneMinder learnings:
https://wiki.zoneminder.com/Various_ZM_thoughts

shrubbery
Posts: 3
Joined: Tue Jul 07, 2020 6:51 am

Re: Digital zoom

Post by shrubbery » Sat Jul 11, 2020 7:07 pm

Thanks for the link - I have started to dig into it and I have realized that tweaking YOLOV3 is slightly more complex than I though and requires a bit of reading first. Will post back once I have some countable results to share.

Cheers

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