Name: offset method for measuring across obstructions
Uploaded: 2025-08-29T12:09:50.000Z
Duration: 1 min 10 s
Channel: JoVE

Consider a field with a lake. A surveyor uses measuring tape to measure the sides of individual areas marked on the field.While measuring the distances of the sides, the surveyor encounters an area edge that crosses the lake. Since the lake is too wide, the tape cannot be stretched across it.The surveyor uses the offset method, which measures distances across obstacles by taking perpendicular measurements from an aligned baseline.To measure the length across the lake, the surveyor sets the side of the area across the lake as the baseline and uses a telescope to align this length from one end to the other.Along the aligned length, the surveyor takes perpendicular offsets of a known length with a compass towards one side of the lake from both ends.The surveyor then measures the distance between the ends of the offsets, which is parallel to the aligned length.Finally, the lengths of the line before and after the lake are added to the distance between the offsets to obtain the total length of the side across the lake.

דוגמת תכנון: מדידת מרחק בין שתי נקודות עם מכשולים

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When measuring distances in areas with physical obstructions, such as a lake in a field, surveyors must employ techniques to calculate accurate lengths ...

design-example-measuring-distance-between-two-points-with-obstructions

Education

JoVE Core

Civil Engineering

הנדסה אזרחית

Unit 1

יחידה 1

Introduction to Surveying

מבוא למדידות

KEY TERMS AND CONCEPTS

מושגי מפתח ומונחים

Design Example: Measuring Distance Between Two Points with Obstructions

offset method for measuring across obstructions

The offset method helps surveyors measure distance across an obstruction such as a lake in a field. It is useful when a measuring tape cannot be stretched in a straight line over the blocked area. The method lets surveyors estimate the true length without direct line measurement.

A surveyor starts by setting up a baseline that lines up with the side of the area across the lake. A telescope is used to check the alignment from one end of the side to the other. This creates an imaginary line over the obstruction and gives clear reference points for the next steps.

Next, the surveyor measures perpendicular offsets from each end of the baseline to points on the lake edge. A compass helps keep these measurements at right angles. The marked offset points form a parallel line that is easier to measure.

The surveyor then measures the distance between the offset endpoints. The full length of the side across the lake is found by adding the measurable distances before the lake, the span between the offsets, and any extra distance on the far side. This gives an accurate total length even when part of the route is blocked.

Offset Method for Measuring Across Obstructions

offset-method-for-measuring-across-obstructions

introduction to surveying, plane surveying and geodetic surveys

introduction-to-surveying-plane-surveying-and-geodetic-surveys

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Survey Taping Tools for Accurate Distance

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taping over different ground profiles

Measuring Tape on Uneven Ground

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distance corrections

Correcting Survey Distance Measurements

Survey distance measurements often need corrections to stay accurate. In surveying and construction, the first step is to adjust for standardization error, temperature changes, and slope. These corrections help turn an initial tape measurement into a more reliable final distance. Standardization error happens when measuring equipment changes over time. Wear, repairs, and weather can all affect the tape or tool. Surveyors compare the equipment readings with a standard to find any difference...

errors in taping

Survey Tape Measurement Mistakes

Survey tape measurements can be affected by several common mistakes that reduce accuracy. Misalignment of the tape is one major source of error. A rear tapeman can use a telescope to guide the head tapeman, but human limits still allow small mistakes in alignment, pin placement, and tape reading. Reading the tape can also be confusing when markings are worn with age. A surveyor may mistake a six for a nine or make other small visual errors. These reading mistakes become more common as the tape...

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Electronic distance measuring instruments, or EDMs, help surveyors measure distance with electromagnetic signals. The instrument sends a signal to a target and then calculates how long it takes to return. This makes EDMs a precise tool for modern surveying. EDMs use two main signal types: light waves and microwaves. Light-wave EDMs use infrared or laser light, so they work well over short distances in clear weather. They give high accuracy, but atmospheric density and particles in the air can...

design example: measuring distance between two points with obstructions

The offset method helps surveyors measure distance across an obstruction such as a lake in a field. It is useful when a measuring tape cannot be stretched in a straight line over the blocked area. The method lets surveyors estimate the true length without direct line measurement. A surveyor starts by setting up a baseline that lines up with the side of the area across the lake. A telescope is used to check the alignment from one end of the side to the other. This creates an imaginary line over...

key terms and concepts

Learn how surveyors use the offset method, a baseline, and perpendicular measurements to find distance across a lake or other obstruction.

Offset Method for Measuring Across Obstructions | JoVE K12

JoVE Core Civil Engineering provides a foundational exploration of essential construction materials in civil engineering, focusing on bricks, stones, steel, wood, and concrete through easy-to-understand animated videos. This collection covers the properties, manufacturing processes, and practical applications of these materials. Additionally, the accompanied science-in-action videos demonstrate the research experiments performed in laboratories.

civil engineering

Offset Method for Measuring Across Obstructions

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