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

ضع في اعتبارك حقلا به بحيرة. يستخدم المساح شريط قياس لقياس جوانب المناطق الفردية المميزة في الحقل. أثناء قياس مسافات الجانبين ، يواجه المساح حافة منطقة تعبر البحيرة. نظرا لأن البحيرة واسعة جدا ، فلا يمكن تمديد الشريط عبرها. يستخدم المساح طريقة الإزاحة ، التي تقيس المسافات عبر العوائق عن طريق أخذ قياسات عمودية من خط أساس محاذاة. لقياس الطول عبر البحيرة ، يحدد المساح جانب المنطقة عبر البحيرة كخط أساس ويستخدم تلسكوبا لمحاذاة هذا الطول من طرف إلى آخر. على طول الطول المحاذاة ، يأخذ المساح إزاحات عمودية بطول معروف مع بوصلة باتجاه جانب واحد من البحيرة من كلا الطرفين. ثم يقيس المساح المسافة بين طرفي الإزاحة ، والتي تكون موازية للطول المحاذاة. أخيرا ، تضاف أطوال الخط قبل وبعد البحيرة إلى المسافة بين الإزاحات للحصول على الطول الإجمالي للجانب عبر البحيرة.

مثال على التصميم: قياس المسافة بين نقطتين مع العوائق

عند قياس المسافات في المناطق ذات العوائق المادية ، مثل بحيرة في الحقل ، يجب على المساحين استخدام تقنيات لحساب الأطوال الدقيقة دون قياسات الخط المباشر. إحدى الطرق الفعالة هي تقنية الإزاحة ، والتي تسمح بتقدير دقيق للمسافة على الامتدادات التي يتعذر الوصول إليها. في هذا السيناريو ، يجب على المساح قياس جانب من المنطقة التي تعبر بحيرة. نظرا لأن شريط القياس لا يمكن أن يمتد على البحيرة ، يبدأ المساح بإنشاء خط أساس يتماشى مع الجانب عبر البحيرة ، باستخدام تلسكوب لضمان المحاذاة من أحد طرفي الجانب إلى الطرف الآخر. تخلق محاذاة التلسكوب هذه خطا واضحا وخياليا فوق العائق ، مما يتيح نقاطا مرجعية دقيقة لمزيد من القياس. بعد ذلك ، يقوم المساح بإجراء قياسات إزاحة عمودية من كل طرف من طرفي خط الأساس المحاذي إلى النقاط الموجودة على حافة البحيرة ، باستخدام بوصلة لضمان أخذ القياسات بزوايا قائمة. من خلال وضع علامة على نقاط الإزاحة هذه على جانبي البحيرة ، ينشئ المساح خطا موازيا يسهل قياسه. ثم يقيس المساح المسافة بين نقاط نهاية الإزاحة هذه. يتم تحديد الطول الإجمالي للجانب عبر البحيرة بإضافة المسافات القابلة للقياس المؤدية إلى البحيرة ، والامتداد بين الإزاحات ، وأي مسافة إضافية على الجانب الآخر. يعكس هذا القياس التراكمي بدقة المسافة الحقيقية عبر البحيرة على الرغم من العائق.

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

الهندسة المدنية

Unit 1

الوحدة الأولى

Introduction to Surveying

مقدمة في المساحة

KEY TERMS AND CONCEPTS

المصطلحات والمفاهيم الأساسية

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

Surveying Methods for Land and Construction

Surveying is the art and science of mapping the earth's surface. It uses measurements of distance, horizontal and vertical angles, and levels to describe the shape and size of land features. Surveying is also used to find the level of a land area with reference to a chosen point. It helps map land undulations and water bodies. These measurements give clear data for planning and field work. Two main surveying methods are plane surveying and geodetic surveying. Plane surveying treats the earth...

types of surveys

Survey Methods for Land and Water

Survey methods for land and water help define property boundaries and map features near water bodies. Each survey type has a different job. Together, they give accurate information for land-related projects and development. Land surveys mark property lines. Route surveys show the position of properties along nearby highways. Topographic surveys create maps by recording the three-dimensional features of the land. Hydrographic surveys examine underwater shapes and the movement of streams...

survey safety

Surveying Field Hazards and Protection

Surveying in the field can bring hazards from roads, rough ground, and nearby power lines. Safety starts with planning the work area and avoiding direct work on roads whenever possible. Surveyors often use offsets instead. An offset means measuring from a safer spot away from traffic. Highway work is especially dangerous and must include warning signs and flagmen. If surveyors must work along a road, they need to follow all safety guidelines. Bright clothing, such as orange reflective vests,...

errors and mistakes in surveying

Survey Measurement Errors and Common Mistakes

Survey measurements can be affected by errors and mistakes. These issues create inaccuracies in measured values and in the way data is recorded. In surveying, errors are unintentional deviations from the true value. They can come from human sensory limits, imperfect equipment, or outside conditions. Mistakes are different from errors. They happen when the surveyor loses attention, misunderstands a procedure, or makes a bad judgment call. Common examples include writing down the wrong value,...

distance measurements by taping

Survey Taping Tools for Accurate Distance

Survey taping tools help measure short distances accurately in the field. Surveyors use tapes because they are durable, flexible, and suited for outdoor work. Many tapes are made from lightweight, nylon-coated steel, which helps protect them from rust and wear. Standard tapes are often about 30 meters long and marked in meters and millimeters for precise readings. Surveyors choose a tape based on the site and the level of accuracy needed. Lightweight nylon-coated tapes are common because they...

taping over different ground profiles

Measuring Tape on Uneven Ground

Measuring tape on uneven ground requires careful setup to keep distance readings accurate. On smooth, level ground with little vegetation, the tape can rest directly on the ground. A taping team usually works with a head tapeman and a rear tapeman. The rear tapeman holds the tape at the start point and helps guide the head tapeman toward a range pole beyond the end point. They use hand signals or voice signals to stay aligned. On sloping ground, uneven terrain, or in dense underbrush, the tape...

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...

electronic distance measuring instruments

electronic-distance-measuring-instruments

Surveying With Light and Microwave EDMs

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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