Unity script to move a camera like in Black and White or almost any 3d strategie game.

CameraControle.cs

using UnityEngine;
using System.Collections;

public class CameraControl : MonoBehaviour {

    public float translateScale = 20;
    public float rotateScale = 1;
    public float zoomScale = 100;

    private Vector3 _lastHitPoint;

	// Update is called once per frame
	void Update () {
        if (Input.GetMouseButton(1))
        {
            //We are translating
            Vector3 move = new Vector3(-Input.GetAxis("Mouse X"), 0,-Input.GetAxis("Mouse Y"));
            Quaternion dir = Quaternion.Euler(0,transform.eulerAngles.y,0);
            transform.Translate(dir * move *Time.deltaTime * translateScale, Space.World);
        }
        if (Input.GetMouseButton(2))
        {
            //We are rotating;
            Ray ray = new Ray(transform.position, transform.forward);
            RaycastHit hit;
            if (Physics.Raycast(ray, out hit, 50, 1<<LayerMask.NameToLayer("floor")))
            {
                _lastHitPoint = hit.point;
            }
            transform.RotateAround(_lastHitPoint, Vector3.up, Input.GetAxis("Mouse X") * rotateScale);
            transform.RotateAround(_lastHitPoint, transform.right, -Input.GetAxis("Mouse Y") * rotateScale);
        }
        if (Input.GetAxis("Mouse ScrollWheel") != 0)
        {
            //We are zooming
            transform.Translate(transform.forward * Input.GetAxis("Mouse ScrollWheel") * Time.deltaTime * zoomScale, Space.World);
        }
        if (transform.position.y < 2)
        {   
            transform.position = new Vector3(transform.position.x, 2f, transform.position.z);
        }
	}
}