As soon as 'we' started using EDMI(s) in our routine Land/Control Surveys in about 1970 (somewhat later than Electra-Tapes for LONG range Control), it became apparent that adjustments for elevation changes were needed for all but the smallest (and/or flattest) projects.
The HP 3800 was the first "daily use" EDMI that I used, usually with either a Wild T-16 or T-2. By the mid 70s we were using HP-3805 or 3810s, and by the late 70s the HP-3820
https://celebrating200years.noaa.gov/distance_tools/hp3800b.html
Inasmuch as our work was primarily in mountainous areas, it was absolutely necessary to get all of the apples, oranges, pears, and plums (distances at different elevations) into the same basket (common elevation), if we had any hope of actually "CLOSING" a traverse (without smearing good data into bad data). This was also about the time we started using [formal] LDPs, SPC, and/or UTM Coordinates on [most] every project.
I fully realize that many folks work in flatter terrain, and maybe on smaller projects, but without actually testing the effects of traversing up and over hills, mountains, etc., one can never really know whether these "corrections" are trivial or non-trivial. Everybody's mileage varies, but the earth is just as "round" in Kansas, as it is in Colorado (Colorado just has bigger lumps).
Loyal
Then there is the total station with its horizontal distance output. Uphill horizontal distances don't match downhill horizontal distance. So this guy avoided downhill shots. (California country, where it's easy to get 100s of feet of elev change and site elevation 4,000.)
I said don't bother even writing down the horizontal distance - up or down hill. I got push back on that. The surveyor in question didn't know why they're different. But a tenth or two didn't bother him.
My favorite 1925 survey text book had the right answer.
Ever use a Tellurometer?
Larry Scott, post: 428338, member: 8766 wrote: Then there is the total station with its horizontal distance output. Uphill horizontal distances don't match downhill horizontal distance. So this guy avoided downhill shots. (California country, where it's easy to get 100s of feet of elev change and site elevation 4,000.)
I said don't bother even writing down the horizontal distance - up or down hill. I got push back on that. The surveyor in question didn't know why they're different. But a tenth or two didn't bother him.
My favorite 1925 survey text book had the right answer.
Ever use a Tellurometer?
Tellurometer, No.
ElectroTape(s), Yes (last time about 1983, on a 206,000 foot shot).
Your comment about Total Station "up hill v. down hill" shots was pretty much the reason for my initial post. To this day...I'm totally amazed by the number of surveyors that don't get the basic geometry (round Earth) that bite's them on the butt.
Loyal
Loyal, post: 428341, member: 228 wrote: Tellurometer, No.
ElectroTape(s), Yes (last time about 1983, on a 206,000 foot shot).
Your comment about Total Station "up hill v. down hill" shots was pretty much the reason for my initial post. To this day...I'm totally amazed by the number of surveyors that don't get the basic geometry (round Earth) that bite's them on the butt.
Loyal
Maybe it takes actually doing it, when you shoot up a steep enough hill, then shoot down the same line (like you are supposed to) and get two different horizontal lengths (both correct) it starts to sink in,,,,,
MightyMoe, post: 428346, member: 700 wrote: Maybe it takes actually doing it, when you shoot up a steep enough hill, then shoot down the same line (like you are supposed to) and get two different horizontal lengths (both correct) it starts to sink in,,,,,
Mean elevation chord is correct.
Horizontal is ambiguous.
Reciprocal vertical angles, then you see what's happening.
