Why this error appears stdClass::$pic_item?

READ the error message! You are looping through a query result, assigning each to $pic_item. Then, in your view, you attempt to reference the pic_item property of $pic_item, and you are being told that $pic_item is not an object. Do a var_dump of $pic_item to see what it is.

You'll need to do the var_dump before referencing $pic_item->pic_item. Your var_dump is not reached beecause of the error message.