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  • 34 Comments
Joined 2 年前
Cake day: 2023年7月26日
  • eltrain123@lemmy.worldtoNo Stupid Questions@lemmy.world•How are roundabouts made?
    7·
    2 个月前

    I used to be a surveyor! The tripods have different tools you can put on top.

    A ‘level’ is used to look at rod (some distance away) with measurement gradations on it, like a ruler, to add or subtract height from its current position to determine elevation. You can transfer measurements long distances by leap-frogging positions of the level and the rod. If you start or end at a known USGS monument, you can tie into historicity known elevations. This is how elevations were mapped before GPS (but the survey markers are still used today). They have some really fancy auto-levels that read a qr-style barcode and can measure down to very precise heights.

    A ‘thedolite’ is a robot-style machine that uses triangulation to determine elevation, distance, and angle. You benchmark it in place so it knows its location, then uses a rod with a prism it can follow. It calculates degrees it turns horizontally and pivots vertically to calculate where you are with the prism. It will automatically guide you to pre-programmed points to lay out very precise locations. Or you can use it to capture really precise points that are in the field. I haven’t been a surveyor in 20years, but they could easily layout points to millimeter accuracy when I was in the game.

    We also used lidar scanners to capture ‘as-built’ maps or calculate volumes of material. A lidar scanner shoots out a laser a few 100,000 times a second as the scanner turns on the tripod. When it bounces off an object, it returns a x,y,z coordinate and a color of the object it bounces off of. When you get a few million returned, you get a point cloud that represents the physical area you are mapping. When you move the scanner and repeat the process, you can map out large areas to a pretty high degree of accuracy. We once used a scan of a statue that was built in the 1800s to compare against the weight of construction materials so we could calculate the crane load expected to move it. Pretty cool stuff!

  • eltrain123@lemmy.worldtoTrump Watch@lemm.ee•Trump brags gas is down to $1.98 a gallon in some states. It isn’t — anywhere
    3·
    3 个月前

    Look up PlugShare. I travel around the country and charge for free at a lot of level 2 chargers. Level 2 chargers get around 15 miles per hour of charge, whereas a regular 120v plug gets you about 3miles per hour. It’s a trade for time, but doable if you have a few hours of doomscrolling or Netflixing. It’s not for everyone, but I’ve managed to cut my transit costs down significantly. Totally understandable if it doesn’t work for you, but I have some freedom in my schedule, work remote, and have internet, so I can sit at a charger for a few hours a few days a week.

  • eltrain123@lemmy.worldtoAsk Lemmy@lemmy.world•What is the absolute last extreme sport you'd be willing to try?
    8·
    9 个月前

    I know you didn’t ask and probably don’t care, but free climbing and free soloing are different things. Free climbing uses a rope, but does not allow you to use artificial means to ascend, like pulling on gear you put on the wall. The gear is just there to arrest a fall.

    Free soloing is where you climb without a rope. Free climbing uses a rope for safety, but upward mobility is hands and feet on wall. Aid climbing is where you climb by fixing gear to the wall and use it to ascend.

    If you know what you’re doing, free climbing is pretty safe. Free soloing is not, but people do it successfully without their huge balls weighing them down.

    As a side note, bouldering is also climbing without a rope, but you don’t climb high enough to make a fall fatal.