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THIẾT BỊ ĐEO
Contouring: Drawing the Shape of the Ground
A traverse gives you the outline of a site. Levelling gives you the height of the points you happened to stand on. Neither tells you the SHAPE of the ground between them — which is what you need to know where water will go, where a building will need cut and fill, and whether a path can be walked.
A contour is a line joining points of equal height. Nobody surveys contours directly; you level a grid of spot heights and then work out where each contour must cross between them, by proportion. The map that results is the single most information-dense drawing in surveying: slope, drainage, volume and visibility are all readable from it.
It is also the rung that makes the water blueprints buildable. A constructed wetland or a drainage run needs to know which way the ground falls, and by how much.
Trung cấp
2 days
Hướng dẫn
1
1
Lay out a grid over the area
Lay out a grid over the area
Set out a square grid of pegs — 5, 10 or 20 metres depending on how broken the ground is — using the right-angle method and a tape. Letter one axis and number the other, so every peg has a name like C4.
Choose the spacing from the SMALLEST feature you care about, not from how much walking you are willing to do. A 20-metre grid cannot see a 5-metre gully, and no amount of careful levelling at the pegs will put it back. The grid is a sampling decision, and it is made before any measurement.
Vật liệu cho bước này:
Chốt gỗ40 cái
Dây bật mực xây dựng100 metre
Bộ cờ và cọc cắm khảo sát1 bộCông cụ cần thiết:
Thước dây cuộn
Búa nhổ đinh2
2
Level every grid point from as few setups as possible
Level every grid point from as few setups as possible
Set the instrument where it can see the most pegs, take a backsight to your benchmark, then read the staff at every visible peg as an intermediate sight.
Intermediate sights are cheap — one instrument setup can produce twenty heights — but they carry no check at all, because nothing closes on them. So move between setups on a proper backsight-and-foresight change point, and close the whole run back to the benchmark at the end. Speed on the intermediates, rigour on the change points.
Công cụ cần thiết:
Máy thủy bình quang học (trắc địa)
Mia thủy chuẩn
Chân máy ảnh3
3
Write the heights on the plan, at the pegs
Write the heights on the plan, at the pegs
Plot the grid to scale and write each reduced level beside its peg, to the nearest 10 millimetres.
Write them small and consistently placed — always above-right of the point, for example — because you are about to draw lines through this drawing and it must stay readable. Do not round to the nearest 100 millimetres to tidy it up: the interpolation in the next step needs the real figures, and a rounded grid produces contours with false steps in them.
Vật liệu cho bước này:
Giấy kẻ ô ly10 cáiCông cụ cần thiết:
Thước kẻ4
4
Interpolate the contour crossings
Interpolate the contour crossings
Between every adjacent pair of pegs, work out where each whole contour value falls, assuming the ground runs straight between them. Mark each crossing with a tick.
The assumption of a straight slope between pegs is exactly that — an assumption, and the only one available. It is why the grid spacing chosen in step 1 governs everything: between two pegs your map is not a measurement, it is a straight line you decided to believe in.
Công cụ cần thiết:
Thước kẻ5
5
Join the ticks, and obey the rules contours cannot break
Join the ticks, and obey the rules contours cannot break
Draw smooth lines through ticks of the same value. Then check them against the rules: contours never cross, never split, never simply stop inside the map, and close on themselves or run off the edge.
They also point UPSTREAM in a valley, forming a V that aims uphill — which is the quickest way to read drainage off a map and the quickest way to spot that you have drawn one backwards. Every one of those rules follows from a contour being a level line on a continuous surface, and a drawing that breaks one has a mistake in it, not an unusual landscape.
6
6
Interpolation, interval and what the map can tell you
Interpolation, interval and what the map can tell you
Đang tải sổ tay Jupyter…
Công cụ cần thiết:
Thước kẻVật liệu
4- 40 cáiTạm thời
- 100 metreTạm thời
- Tạm thời
- 10 cáiTạm thời
Công cụ yêu cầu
6- 1 vendor sell this, none ship to you yetTạm thời
- Tạm thời
- Tạm thời
- Tạm thời
- Tạm thời
Blueprint liên quan
Các blueprint này chia sẻ kiến thức — kỹ thuật, vật liệu hoặc nguyên tắc
CC0 Phạm vi công cộng
Bản thiết kế này được phát hành theo CC0. Bạn tự do sao chép, sửa đổi, phân phối và sử dụng cho bất kỳ mục đích nào mà không cần xin phép.
Hỗ trợ nhà sáng tạo bằng cách mua sản phẩm qua bản thiết kế, nơi họ nhận Hoa hồng nhà sáng tạo do nhà bán hàng đặt, hoặc tạo phiên bản mới và kết nối trong bản thiết kế riêng để chia sẻ doanh thu.