Change is afoot!

[svandamme]

I'm fine with metric time , don't wear a watch anyway
Phone is my time piece, and it can can already do metric time

[Bill Douglas]

Although we have been metric since the 1970's some things are still in feet.

A guy is 6'1" a surfboard is 8 foot 2, a piece of land is four acres.

[GH85Carrera]

Originally Posted by Bill Douglas

Although we have been metric since the 1970's some things are still in feet.

A guy is 6'1" a surfboard is 8 foot 2, a piece of land is four acres.

And virtually all cars manufactured have a SAE bolt and threads for the seatbelt anchor. Tires and wheels are sold in inches.

[javadog]

Originally Posted by GH85Carrera

And virtually all cars manufactured have a SAE bolt and threads for the seatbelt anchor.

True, a 7/16-20... Always wondeed what the story was on that... Goes back years...

[GH85Carrera]

Originally Posted by javadog

True, a 7/16-20... Always wondeed what the story was on that... Goes back years...

What I heard, the US safety standards had that size bolt specified. Since the USA is the biggest part of most car markets, and that is the majority of what parts are on the market for car builders to use, they all adopted it as standard. Even cars made in foreign countries for other foreign car markets find it cheaper to buy a bolt that KNOW is designed to do the job safely and correctly. Why spec a bolt of another size that cost more than the mass produced ones.

[Bill Douglas]

Yeah wheels are the strangest. Mm in one direction, inches in the other.

[Jims5543]

Originally Posted by GH85Carrera

The targets are large white X shape targets that make it simple for us to see that point, and tell our computer this is X,Y & Z and accurate to a very high accuracy (sub MM) since they used a Trimbale GPS or some other brand that gave them super accurate measurement. We ask for a grid of them, in a pattern, and we will be well within the map accuracy standards.

Accuracy:

I was sold this Topcon system I am using now on the basis it would provide me with the accuracy I wanted which was 0.02' to 0.03' horizontal, I was told I would get close to the same vertical, that would be a lie.

I also discovered something horrifying while using it. Just holding the pole in human hands can result in inaccuracies of up to 0.10' or greater. I needed better than that.

Here is my 16 y/o (when he was 15 earlier this year) running it locating utilities and fences. I taught him how to run it in about 15 minutes. Which makes me sad as any idiot can be a land surveyor now.



Once I realized we humans cannot hold the thing steady enough to obtain real accuracy, I purchased some carbon fiber bipods to mount on them. Now we can lock the unit in place and keep it there. We use the bipod mount for any location requiring high tolerance. Then we programmed to the GPS to take thirty separate one second observations then average them out.



We will sit on a property corner or nail in the road for 30 seconds using the bipod locking it into place. We are finally achieving 0.02 or better accuracy horizontal.

Vertical? Not so much I have to use a level to get good vertical, it is wanky at best, I see 0.1' to 0.3' variations all the time. Sometimes it is within 0.01' others it is out to lunch at 0.30'. I am a 1 man crew so I keep a laser level in my truck to use when I need high accuracy like an FFE staked on a house.

What made me realize we were NEVER very accurate was the fact that the pole can move so much, using a standard total station with a prism pole it would not be so noticeable. If we were going for a tight closure we would be using tripods and running a closed loop, turning multiple angles (typically reverse) and taking multiple distance readings.

When we were laying out houses and locating form boards, or even setting corners, I realized just holding a prism pole can result in 0.1' or worse accuracy. This was realized when using the GPS.

The addition of GPS has been a godsend, my next 2 purchases for my company will be a robotic total station then out of left field, a Prius V for my second crew to drive. I realized they are 99% on the pavement in residential settings. I am the one on the construction sites all the time. So the other crew is ditching the 20 MPG pickup truck for a 40+ MPG Prius.

The robot will compliment my GPS so I can truly be a 1 man crew. Right now I sometimes have to steal a guy to help me or take the prismless instrument and set up prism poles on bipods for backsights. Which I have to do next week to do a tree survey. The robot will eliminate that. Plus the robot runs off the same Win10 tablet I am using for my GPS utilizing the same software, I just have to pay to unlock the capability.

[GH85Carrera]

We have a surveyor client that normally works in NW Oklahoma, where he lives. He landed a project here in OKC. He brought his new Trimble GPS unit so he could map out the target locations on a job we were going to fly for him. We just chatting and volunteered to show us the operation of his system. My business partner lives close by so he went and got his DJI drone, and flew my house. We just used crack in the concrete, or corners on sidewalks and various point we could see on the ground. We flew my house twice, and I combined all the images from two flights to "map" my house just for fun. It was insane high resolution, and we could measure the heights of the bricks. One of our Photogrammetry geek customers wanted som sample data to play with. He built a vector 3D AutoCAD line drawing of my house at 1:1 so I have an exact model of my house, and property, and crazy high resolution image of it. It is useless to me for any real purpose, except it is cool.

The Trimble was fun to play with and we just hand held things since we were not really interested in real science and not selling it to anyone.

[Pazuzu]

Originally Posted by GH85Carrera

There are actually two different definitions of the 12-inch measurement known as a foot. Some land surveyors use what’s known as the U.S. survey foot. Others use the definition that’s more accepted by the broader world: the international foot.

They request files in UTM NAD27 (that is a 1927 system) and some ask for meters some want feet. We are not prejudiced, we make it what ever the client wants.
For the most part, our default is NAD83 US Feet. (the 1983 standard, really modern)

I work with feet, survey feet, meters, micrometers, kilometers, kilofeet, all in NAD27, WGS83, UTM N14W99, even ITRF2008 (find me THAT one!). When you are mapping 300-500 square miles, even the small difference between feet and survey feet crops up, and I need to use 5 or 6 decimals when converting between imperial and metric or things get sloppy.

[GH85Carrera]

If you have to work in Texas, I feel sorry for you. We hate Texas projects and trying to figure out which RR survey or rancher's survey was used for a square mile, and then most of the time things are at a weird angle and north is never up. We are happy to accept the Texas projects but it involves more profanity on our part. Of course cussing Texans is a sport around here.

[Pazuzu]

Originally Posted by GH85Carrera

If you have to work in Texas, I feel sorry for you. We hate Texas projects and trying to figure out which RR survey or rancher's survey was used for a square mile, and then most of the time things are at a weird angle and north is never up. We are happy to accept the Texas projects but it involves more profanity on our part. Of course cussing Texans is a sport around here.

I'm working with geophysical data for Oil, so *generally* someone else made the decisions and I just have to follow them, but we do deal with projects in every possible projection from all around the world and sometimes we change projections as we go (legacy data from the 70's in NAD27, and they want the resulted updated to WGS84, etc).

[GH85Carrera]

Originally Posted by Pazuzu

I'm working with geophysical data for Oil, so *generally* someone else made the decisions and I just have to follow them, but we do deal with projects in every possible projection from all around the world and sometimes we change projections as we go (legacy data from the 70's in NAD27, and they want the resulted updated to WGS84, etc).

I feel yer pain.

We had one manufacturing site that was using plant coordinates since the day the plant was plotted. They wanted to everything done to match the old plant coordinates and at the same time have the new images in WGS84 to work with the GPS and laptops. Then they asked us to update all the old paper maps. We "let" them do that themselves.

Of course then they bought the plant next door, and it had a all different plant coordinates and mess of paper plots. I felt sorry for their GIS guy.

[red-beard]

Puerto Rico still uses the Querda, or a "Spanish Acre" which his 0.971 of an imperial acre, which is 0.39295 Hectare.

[red-beard]

When I lived in West Stockbridge,MA, most of the land surveys were done using a bench-mark that was in the wrong place. My house used a granite marker in the backyard (1824 hours), so the survey was one of the few that was correct.