- Principle of Plane Table Surveying
- Equipment Used in Plane Table Surveying
- Types of Plane Table Surveying Methods
- Setting up the Plane Table Surveying
- Procedure of Plane Table Surveying
- Advantages of Plane Table Surveying
- Limitations of Plane Table Surveying
- Applications of Plane Table Surveying
- Frequently Asked Question (FAQs)
Principle of Plane Table Surveying
Simultaneous Plotting and Surveying:
In aircraft desk surveying, measurements are taken on-site, and the corresponding factors are at once plotted at the drawing sheet, lowering mistakes because of reminiscence or transcription.
Graphical Method:
It is primarily based totally on graphical strategies in which strains of sight and distances are drawn without delay onto the paper, representing the surveyed region in real-time.
Orientation of the Table:
The aircraft desk need to be effectively orientated in terms of the floor the use of both a compass or acknowledged factors to make certain correct illustration of the region.
Using a Fixed Scale:
A constant scale is selected to symbolize floor distances at the drawing sheet. All measurements taken withinside the discipline are plotted in keeping with this scale.
Radiation from a Station Point:
From a vital station, rays are drawn at the paper closer to items withinside the discipline. Distances are measured and plotted alongside those rays, organising the positions of factors at the floor.
Accuracy thru Repetition:
The accuracy of plotted factors is stepped forward thru a couple of measurements and replotting, lowering the effect of any observational mistakes.
Direct Sighting with an Alidade:
The alidade is used for sighting the items to be plotted. By aligning the alidade with the object, surveyors can draw strains of sight that correspond to the bodily positions at the floor.
Centering and Leveling:
Proper centering over a acknowledged floor factor and leveling the desk are important for correct plotting. Errors in leveling can motive distortions withinside the map.
Intersection Method for Plotting Distant Points:
For factors that can’t be measured without delay from a unmarried station, the intersection approach is utilized by taking readings from or extra stations, and the factor is plotted in which the sight strains intersect.
Resection for Table Orientation:
If the desk`s function is unknown, the resection approach is used. By sighting acknowledged factors at the floor and plotting them at the map, the desk is orientated and effectively positioned.
Equipment Used in Plane Table Surveying
Plane Table:
The important piece of equipment, it includes a flat board set up on a tripod. The desk presents a strong floor for putting the drawing sheet, wherein discipline measurements are plotted.
Tripod:
The aircraft desk is set up on a tripod that offers aid and stability. The tripod is adjustable to permit leveling of the aircraft desk in one-of-a-kind terrains.
Drawing Sheet:
A sheet of paper is constant at the aircraft desk wherein the surveyor plots the measurements and factors determined in the course of the survey.
Alidade:
This is a sighting tool used to take bearings of the items or factors to be plotted. It includes a directly aspect with a telescope or a easy sight vane for correct line drawing.
Spirit Level:
Used to make sure that the aircraft desk is well leveled. A leveled desk is vital to preserve accuracy withinside the plotting system.
Trough Compass:
This tool enables in orienting the aircraft desk. It is used to align the desk with the magnetic north or with a acknowledged route at the floor.
Plumb Bob:
A plumb bob is used to middle the aircraft desk precisely over the factor at the floor wherein measurements are being taken, making sure accurate alignment and positioning.
U-Fork with Plumb Bob:
Used for centering the desk over the floor factor whilst a further sighting factor is needed for better accuracy.
Ruler and Protractor:
These drawing add-ons are used for measuring angles and distances at the drawing sheet to scale, making sure correct plotting of discipline measurements.
Pins and Clamps:
These are used to stable the drawing sheet to the aircraft desk, stopping motion in the course of the survey system and making sure the sheet remains flat and strong for correct drawing.
Types of Plane Table Surveying Methods
Radiation Method:
In this approach, a unmarried station is used. From this station, rays are attracted to numerous items withinside the field, and their distances are measured and plotted without delay at the drawing sheet.
Intersection Method:
Also referred to as triangulation, on this approach, or extra stations are used. Sightlines are drawn from every station to a far off object, and the object`s vicinity is plotted on the intersection of the strains.
Traversing Method:
This approach includes connecting a chain of stations through measuring distances and angles among them. It is regularly used to survey large regions through developing a traverse of interconnected factors.
Resection Method:
In this approach, the desk is installation at an unknown factor, and the positions of this factor are decided through sighting regarded locations (3 or extra regarded factors) at the ground. The factor is plotted wherein the sightlines intersect.
Plane Table Leveling Method:
This approach is used for contouring and figuring out the relative heights of factors through plotting elevations at the drawing sheet.
Offset Method:
Offsets are taken perpendicular to a first-rate survey line. This approach is beneficial for detailing smaller capabilities like obstacles or homes through measuring their distances from the principle line.
Combination of Methods:
A aggregate of radiation and intersection techniques may be used to boom accuracy, specially in complicated or particular surveys wherein each angular and distance measurements are necessary.
Three-Point Problem:
A precise case of the resection approach, wherein 3 regarded factors are used to discover the placement of the aircraft desk. This approach is beneficial while fewer sightlines are to be had for resection.
Two-Point Problem:
This approach is much like the 3-factor trouble however makes use of most effective regarded factors. The function of the desk is decided through resection and drawing strains from each factors.
Graphic Triangulation:
In this approach, a community of triangles is shaped through plotting more than one factors via radiation or intersection. This approach is regularly used for large-scale surveys wherein more than one stations and factors are interconnected.
Setting up the Plane Table Surveying
Select the Survey Station:
Choose a appropriate place for the aircraft desk in which it has an unobstructed view of the region to be surveyed.
Place the Tripod:
Set up the tripod at the chosen survey station, making sure it’s miles solid and located on flat floor.
Mount the Plane Table:
Attach the aircraft desk securely to the tripod. Make certain the desk is stage with the aid of using adjusting the tripod legs.
Level the Table:
Use a spirit stage to test the horizontal alignment of the aircraft desk. Adjust the legs of the tripod till the desk is flawlessly stage.
Fix the Drawing Sheet:
Secure the drawing sheet onto the aircraft desk the use of pins or clamps, making sure it’s miles firmly connected and does now no longer move.
Center the Table:
Use a plumb bob to make certain the aircraft desk is targeted without delay over the factor at the floor being surveyed. This guarantees correct plotting.
Orient the Table:
Use a compass or a acknowledged reference factor (consisting of a landmark) to align the aircraft desk with the north or the path you need to plot.
Set the Alidade:
Attach the alidade (sighting device) to the aircraft desk. It have to be located on the threshold of the desk for taking correct bearings of objects.
Take Initial Readings:
Sight thru the alidade to seen landmarks or features. Record the distances and bearings as you degree the factors at the floor.
Start Plotting:
As you are taking measurements, plot the factors without delay onto the drawing sheet, the use of the size and orientation you’ve got got set.
Procedure of Plane Table Surveying
Select the Survey Area:
Choose a appropriate place for surveying, making sure there is ideal visibility of the whole place from your chosen station factors.
Set Up the Plane Table:
Position the aircraft desk on a solid tripod, making sure it’s far degree and aligned with the survey place the use of a spirit degree and plumb bob.
Fix the Drawing Sheet:
Secure the drawing sheet to the desk, making sure it’s far well aligned and does now no longer circulate for the duration of the survey.
Orient the Table:
Using a compass or regarded reference factor (consisting of a landmark), orient the aircraft desk in order that the path of north or every other reference is efficaciously marked at the sheet.
Measure and Record Data:
Use the alidade to sight on items or landmarks. Measure the gap from the survey station to the factors and file the data.
Plot the Points:
Immediately plot the factors at the drawing sheet the use of the recorded distances and directions. This is carried out via way of means of drawing traces from the station to the factors, developing a illustration of the place.
Check for Errors:
After plotting some factors, double-take a look at for accuracy. If needed, accurate the orientation or reposition the aircraft desk for greater particular measurements.
Take Multiple Readings:
If the item is remote or tough to reach, take a couple of measurements from distinct stations the use of the intersection or radiation strategies to devise the precise vicinity of the factor.
Move to the Next Station:
Once a fixed of factors has been surveyed from one station, circulate the aircraft desk to a brand new station, and repeat the manner. Each new station need to be targeted over the equal regarded factor the use of the plumb bob.
Complete the Survey:
Continue the manner of measuring, plotting, and checking for all key factors withinside the place. Once all of the factors are plotted, you’ll have a entire map of the surveyed place.
Advantages of Plane Table Surveying
Real-Time Plotting:
The most important gain of aircraft desk surveying is that it permits for fast plotting of the measurements. This reduces the threat of mistakes from reminiscence or transcription.
Simplicity and Ease of Use:
The approach is easy and does now no longer require complicated calculations or instruments. It is straightforward to examine and operate, making it appropriate for novices in surveying.
Cost-Effective:
Plane desk surveying does now no longer require highly-priced system, making it a budget-pleasant choice for smaller-scale surveys or initial web website online surveys.
Direct Observation and Plotting:
The surveyor can see the items being surveyed and plot them without delay at the drawing sheet, which makes the system greater intuitive and accurate.
No Need for Sophisticated Instruments:
Unlike different surveying techniques, it doesn`t depend upon superior era or highly-priced tools. Basic system consisting of a compass, alidade, and spirit degree is sufficient.
Immediate Results:
Surveyors can attain immediately graphical effects throughout the survey, taking into consideration on-web website online decision-making and corrections as needed.
Versatile Applications:
It is beneficial for a number of surveys, inclusive of topographical mapping, production web website online layout, archaeological surveys, or even cadastral mapping in rural areas.
Portability:
The aircraft desk and its additives are light-weight and smooth to carry, making it best to be used in tough or far off terrains in which contemporary-day survey system can be impractical.
Improved Accuracy:
When used correctly, aircraft desk surveying can provide excessive accuracy, particularly whilst more than one measurements are taken from extraordinary stations and plotted the usage of techniques like radiation or intersection.
Real-Time Error Checking:
Since plotting is performed concurrently with measurement, any mistakes or discrepancies may be straight away diagnosed and corrected at the spot, decreasing the want for rework.
Limitations of Plane Table Surveying
Limited Accuracy:
Plane desk surveying is typically much less correct than different strategies, like general station or GPS surveys, because of capacity human blunders in sighting and plotting.
Not Suitable for Large Areas:
This technique is best for small or fairly sized areas. For large, expansive regions, it turns into bulky and impractical because of the want for a couple of setups and common reorientation.
Dependency on Line of Sight:
Accurate plotting calls for clean visibility among the survey station and the items being measured. Obstacles like hills, trees, or homes can impede sightlines, restricting its effectiveness.
Requires Skilled Surveyor:
The technique is based closely at the talent and enjoy of the surveyor. Mistakes in sighting, plotting, or orientation can cause huge errors.
Weather Sensitivity:
Plane desk surveying is touchy to climate conditions. Wind, rain, or intense warmness can reason pain or have an effect on the steadiness and accuracy of the setup, specially while drawing or the use of the alidade.
Time-Consuming:
Compared to fashionable surveying strategies like GPS or digital distance measurement (EDM), aircraft desk surveying is slower because of the guide plotting and common re-modifications of the desk.
Limited Precision in Elevation:
While it’s miles powerful for horizontal measurements, acquiring particular elevation data (for contouring, for example) with a aircraft desk is hard and much less correct.
Labor-Intensive:
The technique may be bodily disturbing because it calls for common shifting of the aircraft desk, adjustment of instruments, and non-stop guide plotting, specially in rugged terrain.
Susceptible to Errors:
Errors in measurement, orientation, or plotting can accumulate, main to distortions withinside the very last map, specially while a couple of stations are used with out right correction.
Not Ideal for Dense Urban Areas:
In city environments with many homes or slim spaces, it’s miles hard to set up clean sightlines, making aircraft desk surveying much less powerful in such settings.
Applications of Plane Table Surveying
Topographical Mapping:
Plane desk surveying is extensively used to create distinctive topographical maps, displaying herbal and man-made functions like roads, rivers, and buildings, particularly in small to medium-sized regions.
Construction Site Layout:
It is frequently used withinside the making plans and format of creation sites, permitting surveyors to mark boundaries, roadways, and constructing positions without delay at the ground.
Land and Property Surveying:
This technique is generally hired for cadastral surveys, assisting in boundary delineation and land possession mapping, particularly in rural or undeveloped regions.
Mining and Quarrying:
In mining operations, aircraft desk surveying is used to map out terrain, plan excavation regions, and assist withinside the format of roads and mines, especially in mountainous or rugged terrain.
Archaeological Surveys:
Archaeologists use aircraft desk surveying to map excavation sites, making sure correct placement of reveals and making plans excavation strategies.
Urban and Rural Planning:
Urban planners use aircraft desk surveying to devise cities, towns, and villages, appropriately mapping out roads, buildings, and public areas for destiny development.
Forest and Wildlife Surveys:
In forestry, this technique is carried out to map out woodland regions, song plant life types, and plan conservation regions or woodland roads.
Road and Railway Surveys:
Plane desk surveying is used to format and plan roads, highways, and railways, together with distinctive mapping of curves, gradients, and intersections.
Hydrological Studies:
It is utilized in mapping water bodies, floodplains, and drainage systems, which aids in water aid control and flood chance assessment.
Educational and Training Purposes:
Plane table surveying is regularly used as a schooling device in instructional establishments for coaching primary surveying concepts, gadget handling, and discipline strategies to students.
Freqently Asked Questions (FAQs)
1. What is Plane Table Surveying?
It is a method of surveying that allows for real-time plotting of measurements directly onto a drawing sheet, using a plane table, alidade, and other basic instruments.
2. Is Plane Table Surveying Accurate?
It offers good accuracy for small-scale surveys but may be less precise than modern techniques like total stations or GPS surveys.
3. What Equipment is Used in Plane Table Surveying?
Essential equipment includes the plane table, tripod, alidade, spirit level, compass, and pins for securing the drawing sheet.
4. What Are the Methods of Plane Table Surveying?
The main methods are Radiation, Intersection, and Traversing.
5. Can Plane Table Surveying Be Used for Large Areas?
It is not ideal for large areas as it becomes cumbersome and requires frequent re-orientation and movement.
