Before GPS, how did surveyors establish control and tie in to the geodetic datum?

Also, on projects where GPS cant such as heavily wooded areas, how is control established to ensure accuracy? Are assumed coordinates used?

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πŸ‘€︎ u/andrewerdna100
πŸ“…︎ Feb 28 2021
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ELI5, vertical datums (geodetic), like Amsterdam's NAP.

How did people understand and establish this in the 1600s?

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πŸ‘€︎ u/JoeWegs
πŸ“…︎ Jul 10 2018
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What are Geodetic Datums? monde-geospatial.com/what…
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πŸ‘€︎ u/monde-geospatial
πŸ“…︎ Apr 02 2015
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Struggling to understand geographical vs projected coordinate systems

Hello, I was hoping to ask this community for some help with some confusion I am having with my layers not matching up in QGIS, and specifically where I am going wrong with my understanding of coordinate reference systems, geographical reference systems, and projected coordinate systems. I was hesitant to post this, since of course there is so much content online that explains this, but I still am unfortunately struggling to understand why I am not able to apply these concepts. I will watch so many tutorial videos that start with the idea of "picture the earth like a sphere, such as an orange peel, you can't just lay the whole thing out flat!", and then just totally get lost afterwards. This confusion popped up again as I am trying to create buffers around centroids, and perform zonal statistics with an underlying raster layer, and the points are just not overlapping with the raster layer, and so I was hoping to ask for some help here so that I might be able to understand these concepts from an applied perspective.

So I have these layers, showing a polygons layer overlapped onto a clipped raster layer.

https://preview.redd.it/2migh5awzrg71.png?width=1278&format=png&auto=webp&s=f4e72b9158238e1145e2b9c72d62aeaf4ab8e14b

Looks good to me, though the problem is when I want to make my buffers. I find the centroids of these polygons, and try to draw buffers around each of them, only to find that the Distance is in degrees, when I want meters. From my understanding, to be able to switch the unit of measurement here from degrees to meters, I would need to "project" the polygons layer. Though I am confused since it appears that my layers already are projected, I think.

For reference, the CRS of my raster layer is:

EPSG:32618 - WGS 84 / UTM zone 18N - Projected

and the CRS of my polygons layers is:

Unknown CRS: GEOGCRS["WGS84(DD)",DATUM["WGS84",ELLIPSOID["WGS84",6378137,298.257223563,LENGTHUNIT["metre",1,ID["EPSG",9001]]]],PRIMEM["Greenwich",0,ANGLEUNIT["degree",0.0174532925199433]],CS[ellipsoidal,2],AXIS["geodetic longitude",east,ORDER[1],ANGLEUNIT["degree",0.0174532925199433]],AXIS["geodetic latitude",north,ORDER[2],ANGLEUNIT["degree",0.0174532925199433]]] - Projected

I tried changing my polygons layer to the same CRS as my raster layer, but then the polygons layer disappeared from being directly overlapped with the raster layer! That is what I don't understand. My raster layer and my polygons layer are now within the same CRS, yet d

... keep reading on reddit ➑

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πŸ‘€︎ u/teledude_22
πŸ“…︎ Aug 11 2021
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Blind Girl Here. Give Me Your Best Blind Jokes!

Do your worst!

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πŸ‘€︎ u/Leckzsluthor
πŸ“…︎ Jan 02 2022
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Dropped my best ever dad joke & no one was around to hear it

For context I'm a Refuse Driver (Garbage man) & today I was on food waste. After I'd tipped I was checking the wagon for any defects when I spotted a lone pea balanced on the lifts.

I said "hey look, an escaPEA"

No one near me but it didn't half make me laugh for a good hour or so!

Edit: I can't believe how much this has blown up. Thank you everyone I've had a blast reading through the replies πŸ˜‚

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πŸ‘€︎ u/Vegetable-Acadia
πŸ“…︎ Jan 11 2022
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What is a a bisexual person doing when they’re not dating anybody?

They’re on standbi

πŸ‘︎ 11k
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πŸ‘€︎ u/Toby-the-Cactus
πŸ“…︎ Jan 12 2022
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Geddit? No? Only me?
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πŸ‘€︎ u/shampy311
πŸ“…︎ Dec 28 2021
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I wanna hear your best airplane puns.

Pilot on me!!

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πŸ‘€︎ u/Paulie_Felice
πŸ“…︎ Jan 07 2022
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E or ß?
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πŸ‘€︎ u/Amazekam
πŸ“…︎ Jan 03 2022
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No spoilers
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πŸ‘€︎ u/Onfour
πŸ“…︎ Jan 06 2022
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Covid problems
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πŸ‘€︎ u/theincrediblebou
πŸ“…︎ Jan 12 2022
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These aren't dad jokes...

Dad jokes are supposed to be jokes you can tell a kid and they will understand it and find it funny.

This sub is mostly just NSFW puns now.

If it needs a NSFW tag it's not a dad joke. There should just be a NSFW puns subreddit for that.

Edit* I'm not replying any longer and turning off notifications but to all those that say "no one cares", there sure are a lot of you arguing about it. Maybe I'm wrong but you people don't need to be rude about it. If you really don't care, don't comment.

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πŸ‘€︎ u/Lance986
πŸ“…︎ Dec 15 2021
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Spi__
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πŸ‘€︎ u/Fast_Echidna_8520
πŸ“…︎ Jan 11 2022
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What did 0 say to 8 ?

What did 0 say to 8 ?

" Nice Belt "

So What did 3 say to 8 ?

" Hey, you two stop making out "

πŸ‘︎ 9k
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πŸ‘€︎ u/designjeevan
πŸ“…︎ Jan 03 2022
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The Truth About Coordinates (And Floating Points) (crosspost)
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πŸ‘€︎ u/AlloyIX
πŸ“…︎ May 19 2020
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I dislike karma whores who make posts that imply it's their cake day, simply for upvotes.

I won't be doing that today!

πŸ‘︎ 15k
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πŸ‘€︎ u/djcarves
πŸ“…︎ Dec 27 2021
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The Ancient Romans II
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πŸ‘€︎ u/mordrathe
πŸ“…︎ Dec 29 2021
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How do you stop Canadian bacon from curling in your frying pan?

You take away their little brooms

πŸ‘︎ 6k
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πŸ‘€︎ u/Majorpain2006
πŸ“…︎ Jan 09 2022
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School Was Clothed
πŸ‘︎ 5k
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πŸ‘€︎ u/Kennydoe
πŸ“…︎ Jan 08 2022
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I did it, I finally did it. After 4 years and 92 days I went from being a father, to a dad.

This morning, my 4 year old daughter.

Daughter: I'm hungry

Me: nerves building, smile widening

Me: Hi hungry, I'm dad.

She had no idea what was going on but I finally did it.

Thank you all for listening.

πŸ‘︎ 17k
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πŸ‘€︎ u/Sk2ec
πŸ“…︎ Jan 01 2022
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It this sub dead?

There hasn't been a post all year!

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πŸ‘€︎ u/TheTreelo
πŸ“…︎ Jan 01 2022
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Couch potato
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πŸ“…︎ Dec 31 2021
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Baka!
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πŸ‘€︎ u/ridi86
πŸ“…︎ Jan 09 2022
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concrete πŸ—Ώ
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πŸ‘€︎ u/Fast_Echidna_8520
πŸ“…︎ Jan 07 2022
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My name is ABCDEFGHIJKMNOPQRSTUVWXYZ

It’s pronounced β€œNoel.”

πŸ‘︎ 14k
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πŸ‘€︎ u/beef_fried_rice
πŸ“…︎ Dec 25 2021
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Why are people so surprised and angry about Djokovic being an anti-vaxxer?

After all his first name is No-vac

πŸ‘︎ 4k
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πŸ‘€︎ u/hangryman23
πŸ“…︎ Jan 06 2022
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If Korean pop is shortened to Kpop and Korean Drama is Kdrama...

What, then, is Chinese rap?

Edit:

Notable mentions from the comments:

  • Spanish/Swedish/Swiss/Serbian hits

  • French/Finnish art

  • Country/Canadian rap

  • Chinese/Country/Canadian rock

  • Turkish/Tunisian/Taiwanese rap

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πŸ‘€︎ u/hootanahalf
πŸ“…︎ Jan 09 2022
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I had a vasectomy because I didn’t want any kids.

When I got home, they were still there.

πŸ‘︎ 7k
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πŸ‘€︎ u/demotrek
πŸ“…︎ Jan 13 2022
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That’s Michelle
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πŸ‘€︎ u/FLEXSEALBREAKER
πŸ“…︎ Jan 10 2022
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Is this sub still active?

There hasn't been a single post this year!

(Happy 2022 from New Zealand)

πŸ‘︎ 10k
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πŸ‘€︎ u/DonStimpo
πŸ“…︎ Dec 31 2021
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Google Earth does this for some reason
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πŸ‘€︎ u/notowa
πŸ“…︎ Feb 07 2020
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If the sea level rises, does the altitude of everything decreases ?
πŸ‘︎ 11k
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πŸ‘€︎ u/zenef
πŸ“…︎ Sep 30 2017
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is Isn't
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πŸ‘€︎ u/mordrathe
πŸ“…︎ Jan 11 2022
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@u/mordrathe - remix
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πŸ‘€︎ u/SpydrRydr
πŸ“…︎ Jan 12 2022
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What do you call a guy with no arms and no legs in a hot tub?

Bob

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πŸ‘€︎ u/4fuchssake
πŸ“…︎ Jan 05 2022
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I named my dog "5 miles."

So that I could frequently say, "I am going to walk 5 miles now."

Edit: My most popular post on Reddit! πŸ˜€ Thank you for the awards.

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πŸ‘€︎ u/javacafe
πŸ“…︎ Jan 10 2022
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My WIFI password is 2444666668888888

Just to clarify, 12345678

πŸ‘︎ 6k
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πŸ‘€︎ u/az1m_
πŸ“…︎ Jan 03 2022
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Possibly the greatest Snap Reaction dad joke I've ever told (it even got me a POWERFUL groan and vehement FU from my wife)

Me grabbing a soda from my (what I thought was) half full 12pk...

Notices there's only 2;

Me: "Awe man... This is a damn bird box!" Her: "What the hell does that mean?!" Me: (Pulls both cans out & shows them to her) "It's only got Toucans."

I'm not ashamed to admit the look on her face was glorious.

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πŸ‘€︎ u/AKhakiNerfHerder
πŸ“…︎ Jan 10 2022
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I can't believe I was arrested for impersonating a politician...

I was just sitting there doing nothing.

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πŸ‘€︎ u/ENJOYblet
πŸ“…︎ Jan 05 2022
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Guns
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πŸ‘€︎ u/PlayYo-KaiWatch21
πŸ“…︎ Jan 10 2022
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The two genders
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πŸ‘€︎ u/ShrimpRex
πŸ“…︎ Dec 27 2021
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If β€œwomb” is pronounced β€œwoom” and β€œtomb” is pronounced β€œtoom” then shouldn’t β€œbomb” be pronounced…

β€œBOOM”?!

πŸ‘︎ 9k
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πŸ‘€︎ u/FourBloodMoons
πŸ“…︎ Dec 24 2021
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A little boy came running up to me and said, "Please help, my dad is in a fight!" I followed him and came across two men fighting, so I asked him, "Which one's your dad?!" He replied, "I don't know."

"That's what they're fighting about."

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πŸ‘€︎ u/808gecko808
πŸ“…︎ Jan 07 2022
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Why did Novak Djokovic pay for his flight to Australia with a Mastercard?

Because his Visa didn’t work.

πŸ‘︎ 6k
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πŸ‘€︎ u/tttestm
πŸ“…︎ Jan 08 2022
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I like my coffee how I like my slaves

free

πŸ‘︎ 8k
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πŸ‘€︎ u/zRepulse
πŸ“…︎ Dec 17 2021
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Why do standup comedians perform poorly in Hawaii?

Because the audience only responds in a low ha

πŸ‘︎ 6k
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πŸ‘€︎ u/husapida
πŸ“…︎ Jan 12 2022
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I couldn’t rush more than this to post it!
πŸ‘︎ 4k
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πŸ‘€︎ u/suaveguile14
πŸ“…︎ Jan 08 2022
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