3.4 Data Collectors, Field Software Jobs, and File Management

3.4 Data Collectors, Field Software Jobs, and File Management

1. Handheld Data Collectors and Field Operating Systems

Handheld data collectors (field controllers) are ruggedized mobile computers running specialized survey field software (such as Trimble Access, Leica Captivate, Carlson SurvCE/SurvPC, or Topcon MAGNET Field).

Hardware Architecture

Field data collectors are designed for extreme site conditions, featuring IP67 or IP68 ingress protection against dust and water immersion. They incorporate full tactile QWERTY/numeric keypads, sunlight-readable touchscreens, long-life lithium-ion battery systems, and integrated wireless communications (Bluetooth, Wi-Fi, cellular data, and long-range robotic radio modems).

The data collector establishes bi-directional communication with total stations and GNSS receivers, logging real-time observations, performing geometric field calculations, and managing project databases.

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2. Core Field Software Routines

Survey field software organizes tasks into standardized operational routines:

Topographic Survey Routine

Used to record 3D coordinates and descriptions of existing site features (natural ground, utilities, pavement, structures). Features can be stored individually by pressing a trigger key or logged continuously using auto-store parameters (storing points automatically by time interval or distance traveled).

Construction Stakeout Routine

Provides graphical guidance to navigate a rodperson to a target design coordinate ($N, E, Z$) or design alignment line (station and offset). The data collector screen displays real-time navigation directions (e.g. Go North 4.25 ft, Go East 1.10 ft, Fill 0.85 ft).

Resection Routine

Allows a survey crew to set up the total station at an arbitrary, un-monumented location (an unknown station) with clear sight lines. By measuring horizontal angles, vertical angles, and slope distances to two or more known control points, the field software computes the instrument station's coordinates ($N, E, Z$) using least-squares or trigonometric intersection.

Traverse Routine

Used to establish boundary and control networks. The software guides the operator through systematic sets of direct and reverse telescope observations (Face 1 and Face 2 / Sight Right and Sight Left) to eliminate instrument mechanical axis errors. It tracks angular closure error and computes field traverse closing precision (e.g. 1:20,000).

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3. Feature Coding and Line Work Conventions

To convert field measurements into structured CAD drawings efficiently, survey crews assign standardized feature codes (point descriptors) to every point collected.

Point Descriptors

Alphanumeric codes describing ground features:

• IPF = Iron Pin Found
• MON = Monument
• EP = Edge of Pavement
• CL = Centerline
• MH = Manhole
• UTIL = Overhead Utility Pole

Line Work Control Codes

Action codes appended to descriptors that instruct office CAD software to draw polylines, 3D breaklines, and smooth curves automatically upon import:

• ST or BEG: Start a new line feature (e.g., EP ST).
• END: End the active line feature.
• PC: Point of Curvature (start of a horizontal arc).
• PT: Point of Tangency (end of a horizontal arc).
• CLS: Close polyline back to starting point (e.g., for a building footprint).

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4. Raw Data Files vs. ASCII Coordinate Formats

Survey project data is categorized into two distinct file types: raw observation files and processed coordinate export files.

Raw Data Files (.RAW, .RW5, .JOB)

The raw data file is an unedited, chronological ledger of all physical measurements recorded during field operations. It records every occupied station setup, backsight reference angle, measured slope distance, zenith angle, instrument height ($HI$), target height ($HT$), and prism offset.

• Audit Trail Integrity: The raw file forms an unalterable legal record. If a target height was incorrectly entered as 5.50 ft instead of 5.00 ft in the field, the raw file can be edited in the office to recalculate all downstream point elevations correctly without re-running the field survey.

ASCII Coordinate Export Files (.TXT, .CSV)

ASCII coordinate files contain calculated flat 3D point lists exported for CAD drafting or client deliverables. The most universally recognized format is PNEZD (Comma-Delimited):

$\text{Point Number, Northing, Easting, Elevation, Description}$

101,1005234.125,543110.850,452.15,IPF
102,1005280.450,543195.210,454.80,EP ST
103,1005315.600,543250.100,456.25,EP PC

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5. Daily Backup Protocols and Data Security

Data loss in the field due to hardware failure, dropped controllers, battery corruption, or accidental job deletion can cost thousands of dollars in lost crew hours.

[!IMPORTANT] Data Security Golden Rules:

1. Back up data files at the end of EVERY working day to a secure cloud server or external USB thumb drive.
2. Never delete raw data files (.RW5 / .RAW) from the data collector until verified intact on office backup servers.
3. Always maintain separate project jobs in the field controller for distinct field dates or tasks to prevent accidental coordinate overwrites.