Is it considered invasion of privacy when the local library has surveillance cameras on you house?

I live about 200ft from the local public library, in front of it. It sits directly on the elbow on a 90 degree curve, and I live on the street in a house just before the curve, so if you can visualize it, I am diagonal from them. This by the way is a small library, in an even smaller town. I was just recently informed by a police officer that they have my home, as well as the few surrounding homes, under surveillance. He said the video he saw showed my daughter (she's 10) coming out of our front door and meeting another little girl to play on the sidewalk, where they proceeded to walk to the library and sit on their front steps, which are again exactly diagonal from my home.

I want to know, is this legal for them to do? As a mother of 3, I spend countless hours on my front porch, which is large. I sit out here and watch my kids play, and at night, I sit out here alone, or with my husband on the weekend nights, to enjoy the peace and quiet.

I was never made aware of them taping my front porch. And neither were any of my other neighbors. The only way I found out was because they (the library) had the gall to call the cops on my 10 year old daughter for sitting on the library steps after hours on a sunday night. All she was doing in the video was playing with some rocks. What is so terrible about that??? He even joked, "She's not quite a juvenille delinquent yet." I was outside on my front porch watching her. If they felt this was uncalled for, they should have come to me, so why call the cops?

The majority of the women that work in our public library shouldn't even be there. They are so rude, and treat kids just terrible, so I don't even let mine go over there anymore. It shouldnt be that way, my kids love to read, so I now buy their books. And most workers (and head librarian) are ex-public school teachers substitutes in their 60's, if that give you any idea.

Anyhow, the cop said based upon the video, my daughter did absolutely nothing wrong, BUT he still had to follow up on their complaint and come over to my house. And until this happened, I had no clue that every hour I spent on my porch was being watched by THEM if they so felt the need to delve into my private life. By the way, again, this is a small town, and this street is fairly low traffic, few homes, and very quiet at night.

So again - isn't this illegal? Can't something be done about it? We live in Indiana.