[nonSurveyor] Relative height of 2 summits (200 yds apart)

Leveling would probably be the easiest procedure for a non-surveyor to pull off, but the accuracy of the results would depend on how well your rental level is adjusted. The problem with leveling is that you want to be set up between the two peaks, rather than sitting on one peak and looking at the other, which looks to be impossible here. When taking a very long sight, and very short sight, with a level of unknown calibration, the results will have an unknown accuracy, and probably not 1". There is a procedure called a "peg test" that will tell you how out of calibration your level is. And 600' is really pushing the limits of what a level was designed for ...

It would be very easy to do with a total station or high precision GPS, but it's not the type of thing an inexperienced non-surveyor would want to jump into, unless you had a rental source that could give you a very good short course on how to accomplish your mission here.

You would usually set up the instrument some distance from the first point of interest (ideally halfway between points of interest if elevations permit) and hold a rod on that point. Then the reading tells you how far above the point the instrument is. Then you put the rod on the second point and its reading tells you how far below the instrument that point is. Simple arithmetic gives the difference in elevations.

I haven't studied this tutorial to know if I agree with everything (it has a LOT of detail), but it might be helpful.
http://www.levelling.uhi.ac.uk/

I'm not sure I understand your picture. I don't see any dropoffs between the peak on the right and the more distant one that still looks black. The ones that look blue must be a lot more than 200 yards away.

Rent a 5 second total station and two prism rods. Adjust both rods so the prism is at the same height. Securely place a prism rod on both summits and measure down from the prism center to the summit. Orient both rods to a spot where you can see both with the total station. You will probably have to recon the best spot out first and then mark it somehow for rod orientation. Set up the total station and shoot the prism centers. The vertical difference you will be seeing on the total station is the + or - height difference from the total station vertical axis center to the rod prism centers...simple subtraction will give you your answer.

If it was me, I would do it with my level from one peak. I wouldn't need someone on the other peak.

Just keep moving the level up or down until I was hitting the highest point on the far peak and then shoot the peak that I am on. If i happened to pick the highest peak to climb first then I would mark a rock nearby (turning point). Set my level up higher then shoot my mark then shoot the highest point of the peak I am on. If I am sitting on the lower peak then one shot is all it takes.

If I was using someone else's level or if accuracy is important, then climb the other peak and do the same thing. Taking a long shot then short shot from each peak and averaging them would have the same result as sitting in the middle with balanced shots which obviously you can't do.

The only shot you would be taking would be short so a tape measure would work assuming the 0-4 feet difference is correct. That would save on equipment you would have to carry.

James

I just looked at the picture..that peak difference looks a lot more than 4 feet

Where is the mountain.

Simplest answer is make friends with a surveyor 🙂

Sounds as if your looking to confirm which of the two summits is the higher. It might be worth investigating whether a local surveyor might want to get involved for fun and a bit of publicity, that way you'd have the job done using GPS and have confirmed absolute heights. That would involve a set up on each summit, perhaps a couple of hours on each. At a minimum it would require a mini tripod, GPS receiver and tribrach mounting.

A similar exercise has been carried out in the UK where it's important to some people to confirm which mountains are over 3000' there's a summary here:

http://www.themunrosociety.com/heightings.html

I would do it with a self leveling level, fiberglass or aluminum legs and a pocket rod which is a pocket tape of sorts, with graduations marked out to read through a instrument.

I pretty much agree with James on approach.

Climb one peak and "wiggle in" on the top of the other which means to set up and adjust up and down until the level line of site is on the top of the other peak.

If the instrument is now above the peak you are on site the rod and measure the difference, if you are set up directly over the peak you are on measure down from the vertical center of the instrument to the ground.

If below you will need to "turn" which involves marking a intermediate point with a "minus" shot, setting up the instrument in a new location, reading a "plus" shot and then taking a shot on the peak where you are set up. If conditions allow you could skip the turning part altogether and just measure up from your line of site to the peak.

I disagree with James about the virtue of adjusting out two long shots being as tight as taking a balanced shot as 600' is way beyond how far you are supposed to shoot for tight, adjustable reads.

I would have low confidence in your measurements as this will be your first time, I would bring a helper just on principle and would practice in a park with easy conditions before hand. I would also try and go early in the morning to avoid heat waves.

Looks kinda like the North Cascades. Give me a call and I'll come help you....

I would favor a long static GPS session.

Two survey grade receivers, one on each peak running simultaneously to be post-processed later. Let them run for a couple of hours.

My ProMark3s would be ideal for the purpose because them and their poles are fairly lightweight.

If you want to use an optical method (such as Level or Total Station) then I would favor a total station. It would be best to observe both ways to cancel out refraction. Set up the total station on one peak, observe the target on the other in both faces several times. Then trade places with the rodman and do it again from the other peak.

Paul Plutae's method would take a lot less time, the total station would not have to go all the way to the top of either peak and the results would probably be good enough. Again do several observations in both faces. Most modern total stations will give you vertical and horizontal distances but you have to take into account the height of the targets. If the targets are the same height on both peaks then the height of the instrument doesn't matter.

Make friends with a surveyor.
Take a decent reflectorless instrument, in a backback, and a light tripod to the accessible peak.
Shoot both peaks.
Come back down again.

Pros
No issue if there's a larger than expected height difference that a level staff can't cover.
No need to access the far peak.

Cons
Gear's expensive.
Heavier than a level.

Do I smell zipline grease in the air??

Thanks for all the replies so far. I think I'd prefer an optical method to the GPS solution.

Any tips on renting a Level or Total Station? What should I pay for a daily rental?

RADAR: Yep, It's in the Cascades. It's Snoqualmie Mountain, accessible via a steep hike from the Alpental Ski Area parking lot at Snoqualmie Pass. Are you up for the hike, or just showing me how to use the equipment? It's the same elevation gain as Mount Si, but over a shorter/steeper route.

It's just academic at this point... probably need to wait another month or more for the snow to melt off the summits.

First you get 600 feet of 1/2" plastic pipe. Take it to the top of one summit and assemble vertically. Then tip it over so each end is on a different peak. Add a "T" with five feet of pipe. Poor water in the pipe until it runs out the far end. The depth in the standpipe will tell you the amount your peak is lower than the other peak. If it all runs away no matter how much you put in, you are on the higher peak. Remove the standpipe and move to the other peak and repeat the process.

Or better yet, ignore anything I suggest.

> ........Total Station? What should I pay for a daily rental?

A 5 second manual with two rods, reflectors and bipods should run less than $100 a day

You were very precise in your post about wanting to achieve 1 second angular accuracy. Not sure why you would need to be so precise about it. To me, it sounds like you want to measure the vertical angle from the lower rounder summit, where you can easily set up a tripod, to a target on the upper, rocky summit.

Can you even set up a tripod on the rocky summit in the foreground of the picture?

How about a high quality theodolite? Taking many measurements in both faces, discarding outlyers, enough to meet the required specification of 1 second. A high end Wild theodolite, the T2 or T3, would satisfy this precision requirement. But, it should be paired with a user who knows how to do it well. If you haven't operated a high precision theodolite, I wouldn't recommend this approach.

Do you need the absolute elevation, or only the relative elevation between the two points?

I'm pretty sure he was looking for 1 inch accurancy, vertically.

Yes, of course! That makes much more sense!