help with zones and blobs

aot2002 · Post by **aot2002** » Thu Jun 16, 2005 3:37 pm

Using zones can someone show me a basic alert setting which will alarm at the size of a cat or dog...right now i have kids on bikes riding about 100ft away and it doesnt alarm on them im guessing its because of the size of the blobs

Post by **cordel** » Thu Jun 16, 2005 6:07 pm

Hi jay,
Theres really not information here to help you. I depends on the image size + the lens +the distance from the camera. I would take the type off of percent and start working with the real numbers. Then you can work you way down to what you need by changing (this is to help you have a closer guess) the zone location values for both x and y minimum to zero and then adjust the maximum x and Y to be about the size (your looking for the mass of the cat so the box will need to be slightly smaller) of you target cat. This well give you an idea of what the minimum values for your filters and blobs ect... will need to be.
Hopfully that helps you get going.
Oh and don't for get to set your zone location setting back

regards,
cordel

Post by **zoneminder** » Fri Jun 17, 2005 1:18 pm

A few tips. Firstly, I would always recommend having the filter settings as 3 and 3 at least. I notice you have height left blank. Next, I suspect your minimum areas of 15% are probably quite large when you consider that would be about 1/6th of the area of your image so that could probably be a lot smaller. Also, you have 15 for 'minimum blobs' which implies 15 separate contiguous areas of interest. So 15 cats might trigger it but my cat (now sadly departed) in this image

is pretty much always one or two blobs and I suspect most of the time so is yours

Finally, I think it's always easier to go too sensitive and then reduce slowly as that way you will get events and you can check the stats to see what actual values were generated which will give you an idea of the dimensions of the various things that might trigger events.

Phil

aot2002 · Post by **aot2002** » Sun Jun 19, 2005 1:12 am

what do these represent ?

Minimum Blob Area
Maximum Blob Area

maciekc · Post by **maciekc** » Sun Jun 19, 2005 5:35 pm

I have:
units pixels
min pixel thres 10
max pixel thres 0
min alarm area 100
max alarm area 0
filter h 3
filter w 3
min filter area 100
max filter area 0
min blob area 100
max blob area 0
min blobs 1
max blobs 0
Good for indoor use, and only for good class cameras.
minimum blob area is the minimum area which one blob is. Everything is explained very good in documentation
Also try Reference Image Blend %ge in Misc in camera setting. I have 20.

aot2002 · Post by **aot2002** » Mon Jun 20, 2005 5:35 pm

but what do they mean?

Post by **zoneminder** » Tue Jun 21, 2005 10:26 pm

A blob is a contiguous (ie joined together) area of alarmed pixels. So you have 25% of the pixels in your image alarmed, but if none were touching you'd have thousands of blobs (though filtering would hopefully have removed them), however if they were all in the middle you'd only have the one blob. The idea is to help separate images caused by a body for instance and rain or snow or static.

The min and max areas just indicate how big or small the range of blob sizes that might trigger alarms should be.

Phil

Ruler · Post by **Ruler** » Thu Jun 23, 2005 9:50 pm

Sorry to hear about your cat Phil.

Post by **zoneminder** » Fri Jun 24, 2005 8:03 am

Thanks. Oddly enough he slipped (having been ill for a couple of weeks) on his favourite cushion in the sun pretty much exactly where he is in that picture.

Phil