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A short class with Sarah and her students. The other ways are under More.
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Today we will learn about the three main steps involved in using a plane table effectively. Can anyone tell me what the first step is?
Is it levelling the table?
Correct! The first step is levelling the plane table. What do we use to level it?
A spirit bubble tube!
Exactly! Next, we need to centre the table. Can someone explain how we do that?
Using a plumb bob!
Well done! And lastly, how do we orient the plane table?
We can use a magnetic compass or the back ray method.
That's right! To recap: we level using a spirit level, centre with a plumb bob, and orient using a compass or back ray method.
Now, let's dive into the four methods of plane tabling! Who can name one of these methods?
Radiation?
Yes! The radiation method involves using distance and direction. Can anyone explain how it works?
We set the table at a location and measure the distances to points around us, drawing rays to locate them on the map.
Excellent! What about the second method?
Intersection!
Right! This method helps to locate points using two directions from two stations. Let’s move to the third method.
Traversing!
Spot on! This is used when visibility is obstructed and involves multiple stations. Finally, what is the last method?
Resection?
Correct! Resection allows us to determine our unknown position by referencing known points. Great job, everyone!
As we know, traditional plane tabling is becoming rare. Let’s discuss why that is. Can anyone give a modern alternative?
GPS and total stations!
Exactly! While these technologies provide more efficiency, what benefits do you think plane tabling has?
It’s very accurate and you can work in the field with minimal office work.
Right! The ability to check plotting errors on the spot is another advantage. However, what about its disadvantages?
It’s labor-intensive and not good in dense areas.
Perfect! Plane tabling, while less popular now, offers valuable techniques for understanding basic surveying principles.
Ensuring the plane table is horizontal.
Accurately placing the table over the survey point.
Aligning the table with the terrain.
A way to map points based on direction and distance.
Locating points using two directions from two points.
Plotting points in obstructed visibility conditions.
Finding the unknown location by referencing known points.
To level the table, bubble straight, centring's next, don’t be late! Orient well, with compass right, plane tabling's easy, what a sight!
Imagine a surveyor in the field, carrying a wooden table and a spirit level. As they move to various sites, they take a plumb bob to ensure they center perfectly over each point, and they spin their compass to find true north before tweaking the angles for accurate mapping. This sequence of actions ensures the best possible outcome.
L-C-O: Level, Centre, Orient – the steps you need to survey well!
R.I.T.R. – Radiation, Intersection, Traversing, Resection – remember these methods to master plane tabling!
Term
What is Levelling?
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Term
Describe the Radiation Method.
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Term
What is Resection?
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Term
What does Centring accomplish?
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The process of making the plane table horizontal using a spirit bubble tube.
Positioning the plane table directly over a survey point using a plumb bob.
Aligning the plane table with a reference direction using a magnetic compass or back ray method.
A method of locating points on a map by measuring distances and directions to those points.
A technique for locating an object by taking directions from two different stations.
Plotting details by occupying multiple stations, especially in obstructed visibility areas.
Determining the position of an unknown point by drawing rays from known points on the plane table.
This section discusses the three main steps involved in using a plane table for surveying and outlines the four principal methods for effective plane tabling.
It details the processes of levelling, centring, and orienting the plane table, as well as describing the four methods of plane table surveying - Radiation, Intersection, Traversing, and Resection. Each method’s operational specifics and applications are examined, emphasizing their relevance in mapping despite modern technology overshadowing traditional approaches.
The section elaborates on the process and methods involved in plane tabling, which has been a fundamental technique in surveying and mapping. Plane tabling involves three crucial steps: Levelling, Centring, and Orienting. Levelling is conducted using a spirit bubble tube to ensure the table is horizontal, while Centring requires a plumb bob for precise placement over a survey point. Orienting can be achieved using either a magnetic compass or the back ray method to align the table with true north.
Four main methods of plane table surveying are discussed:
Despite the accuracy and immediacy of plane tabling in fieldwork, modern advancements like GPS and total stations have rendered traditional plane tabling methods almost obsolete. However, their foundational principles remain vital for understanding surveying techniques.