if not using a laser, the only other forms of optical rangefinding are subtension and coincidence. Mil dot and similar use subtension to estimate range. You must know the height/size of the object, any reference object.
Coincidence is used in military long range rangefinders and look like big bug eyes. Two lenses far apart give the user two images. When the optics are adjusted so that the images coincide, a guage shows the range.
GPS and the methods of using topo maps are also useful but can have significant errors, enough to cause a miss at long range.
Those lasers are really the way to go.
Jerry