Differentiate between an oblique off set and an inline offset as used in linear surveying?

In linear surveying, an oblique offset and an inline offset are two different methods used to measure distances or locate points that are not directly accessible from the survey line.

1. Oblique offset:
- An oblique offset is a measurement taken at an angle from the survey line to a point of interest.
- It is used when the point of interest is not directly accessible from the survey line, such as a building or a boundary marker.
- The measurement is taken perpendicular to the survey line, and the distance is calculated using trigonometry.
- An oblique offset is typically used when the point of interest is located at a significant distance from the survey line, and a direct measurement is not feasible.

2. Inline offset:
- An inline offset is a measurement taken parallel to the survey line to locate a point of interest.
- It is used when the point of interest is located along the survey line, but not directly on it.
- The measurement is taken perpendicular to the survey line, and the distance is calculated using simple geometry.
- An inline offset is typically used when the point of interest is located close to the survey line, and a direct measurement is not necessary.

In summary, an oblique offset is used to measure distances at an angle from the survey line, while an inline offset is used to measure distances parallel to the survey line. Both methods are important in linear surveying to accurately locate points of interest that are not directly accessible from the survey line.

Oblique Offset

- Measurements are taken at an angle to the survey line.
- The offset distance is perpendicular to the survey line.
- Used to determine the location of features that are not directly on the survey line, such as:
- Buildings
- Obstacles
- Boundaries
- Requires the use of a perpendicular offset rod or a transit to measure the angle.

Inline Offset

- Measurements are taken parallel to the survey line.
- The offset distance is measured directly along the survey line.
- Used to determine the location of features that are close to and parallel to the survey line, such as:
- Utilities
- Property lines
- Fences
- Requires the use of an offset tape or a measuring wheel to mark the offset distance.

Key Differences

| Feature | Oblique Offset | Inline Offset |
|---|---|---|
| Measurement direction | Perpendicular to survey line | Parallel to survey line |
| Offset distance | Perpendicular to survey line | Parallel to survey line |
| Purpose | Features not on survey line | Features close to and parallel to survey line |
| Measurement tool | Offset rod, transit | Offset tape, measuring wheel |