---
title: "Intersection versus resection in plane tabling"
subject: "Surveying I"
chapter: 6
key: "semester_3/surveying_i:intersection-vs-resection-plane-table"
source: https://www.bctengineer.com/q/semester_3/surveying_i/intersection-vs-resection-plane-table
site: BCT Engineering
---

# Intersection versus resection in plane tabling

Surveying I · Chapter 6: Plane Table Survey

- Asked in: 2062 Baisakh, 8 marks
- Video: [Resection Method in Surveying](https://www.youtube.com/watch?v=m-ds6ZxQ_Ic) — Rami Tamimi | Professional Surveyor
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_3/surveying_i/intersection-vs-resection-plane-table
- Whole chapter: https://www.bctengineer.com/md/semester_3/surveying_i/chapter-6

## Question

Distinguish between intersection and resection methods of plane table survey.

## Short answer

Intersection locates an object by forward rays from two plotted stations using only the measured base line, useful for inaccessible points. Resection locates the table station by backward rays from plotted points without measuring distances, employing two‑point or three‑point problem solutions.

## Answer

**Intersection** is the method in which a point is located by drawing rays to it from two known plotted stations. **Resection** is the method in which the table station itself is located on the sheet by drawing rays back from known plotted points to the station.

| Basis | Intersection | Resection |
|---|---|---|
| What is located | The point sighted (object) | The table position (instrument station) |
| Known data | Two stations plotted; base line known | Two or three well-defined points plotted |
| Rays drawn | From a and b forward towards the object | From a, b, c backward towards the table position |
| Table set at | The known stations A and B | The unknown station P |
| Orientation | By back-sighting along the base line | By back-sighting or by trial; must be correct for the rays to meet |
| Distance measured | Only the base line | None |
| Typical use | Inaccessible or far objects | Locating a new, convenient table station from already plotted points, e.g. to fill in details |
| Types / problems | No special problem | Two-point and three-point problems; triangle of error |
| Check | A third ray from another station | A fourth point sighted from the located station |

```text
 INTERSECTION              RESECTION
   p (to be found)       a     b     c  (known)
   /\                     \    |    /
  /  \                     \   |   /
 a----b  (known)             \  |  /
                              p (to be found)
```

In intersection the unknown is where the rays meet *forward*, while in resection the unknown is where the rays meet *backward* from known points.

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. What is located in intersection compared with resection?
   A. Intersection locates the table station; resection the object
   B. Intersection locates the sighted object; resection locates the table station
   C. Both locate the object
   D. Both locate the table station
   Answer: B. In resection the unknown is the instrument station itself. (Key point: What is located)

2. How are rays drawn in resection?
   A. Forward from two stations to the object
   B. From the table towards unplotted points
   C. Backward from the known plotted points to the table position
   D. Parallel to the base line
   Answer: C. Rays are drawn back from a, b, c and meet at the station. (Key point: Ray direction)

3. What distance is measured in each method?
   A. Intersection: none; resection: base line
   B. Both: all rays
   C. Both: none
   D. Intersection: base line only; resection: none
   Answer: D. Resection uses only known plotted points. (Key point: Distance measured)

4. What gives the check in resection?
   A. A fourth point sighted from the located station
   B. A third ray from another station
   C. The base line length
   D. The compass needle
   Answer: A. Intersection is checked by a third ray; resection by a fourth point. (Key point: Check)

## Related in Surveying I

- [Two-point resection in plane tabling](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Atwo-point-resection-plane-table) — Surveying I, chapter 6
- [Methods of plane table survey](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Amethods-of-plane-table-survey) — Surveying I, chapter 6, asked 6×
- [Working principle of plane table survey](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aworking-principle-plane-table) — Surveying I, chapter 6
- [Advantages and disadvantages of plane tabling](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aadvantages-disadvantages-plane-table) — Surveying I, chapter 6, asked 2×
- [Orientation in plane tabling; reliable method](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aorientation-more-reliable-method) — Surveying I, chapter 6, asked 2×
- [Plane table principles; orientation by back sighting](https://www.bctengineer.com/question.md?key=semester_3%2Fsurveying_i%3Aorientation-back-sighting) — Surveying I, chapter 6, asked 4×

## Related in other subjects

- [Intersection vs resection, three point method](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Aintersection-vs-resection-three-point) — Surveying II, chapter 5
- [Define intersection and resection, derive](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Aintersection-resection-define-derive) — Surveying II, chapter 5
- [Resection, two point problem, intersection](https://www.bctengineer.com/question.md?key=semester_4%2Fsurveying_ii%3Aresection-two-point-problem-ab-p) — Surveying II, chapter 5
- [Coplanar lines, intersection point and plane](https://www.bctengineer.com/question.md?key=semester_2%2Fmathematics%3Acoplanar-lines-intersection-point-plane) — Mathematics, chapter 3, asked 2×