Tablet Survey

Overview

Tablet survey, also known as plane table surveying, is a direct graphical method of surveying and mapping that involves plotting survey data directly onto paper in the field. This technique uses a portable drawing board mounted on a tripod, eliminating the need for extensive calculations after fieldwork is completed.

Equipment and Components

The primary instrument in tablet surveying is the plane table, which consists of a flat wooden or metal board mounted on a tripod. The board is typically 60 cm × 45 cm in size and can be adjusted for height and angle. An alidade, a straightedge with sighting vanes or telescopic attachment, is placed on the board to measure angles and directions. Additional tools include:

Trough compass for orientation

Scale rulers and triangles

Drawing pencils and erasers

Plumbing fork to ensure vertical alignment

Methodology

The tablet survey process begins by establishing control points with known coordinates. The plane table is set up at these points and oriented using a compass or backsighting method. The surveyor plots their position on the paper attached to the board.

From the established point, the alidade is aligned with visible objects or features. The surveyor draws rays along the alidade's edge toward each feature. By measuring distances using tape or rangefinding methods, the surveyor can plot the exact position of features by intersection of rays from multiple stations.

This process is repeated from different setup positions, creating a comprehensive map as fieldwork progresses. The graphical plotting allows surveyors to immediately identify missing data or areas requiring additional measurements.

Advantages

Tablet surveying offers several significant benefits:

Immediate visualization: Maps are created in real-time, allowing surveyors to verify data completeness

Reduced calculations: Direct graphical plotting eliminates extensive office computations

Quick feedback: Errors or missing information are identified immediately

Cost-effective: Minimal equipment and personnel requirements for certain applications

Flexibility: Well-suited for irregular terrain and complex features

Limitations

Despite its advantages, tablet surveying has notable drawbacks:

Weather dependency: Rain, wind, and extreme temperatures affect fieldwork

Accuracy constraints: Limited precision compared to modern electronic methods

Physical challenges: Difficult to use on steep slopes or obstacles

Scale limitations: Paper size restricts map extent

Operator skill: Results heavily depend on surveyor experience and technique

Modern Applications

While tablet surveying has been largely replaced by digital technologies such as GPS, total stations, and GIS systems, it remains valuable for:

Geological and environmental field studies

Archaeological surveys

Reconnaissance surveys

Educational purposes in surveying programs

Areas lacking modern surveying infrastructure

Historical Significance

Tablet surveying was a dominant method for centuries before electronic instruments became prevalent. Its development allowed faster mapping compared to transit-based methods, significantly advancing cartography and land documentation.

Conclusion

Tablet survey represents an important surveying methodology that bridges traditional graphical techniques and modern digital approaches. Though superseded by contemporary technology in most professional applications, understanding plane table surveying principles remains valuable for surveyors and students comprehending the evolution of the discipline and its fundamental concepts.