Drones, Lidar, and GNSS: What Modern Surveying Technology Means for California Projects

A survey crew used to mean two or three people walking a site with a total station, collecting points one at a time. That work is still the backbone of precise surveying. But drones, laser scanners, and satellite positioning now capture far more of the site in far less field time.

For owners, developers, and agency staff, the change shows up in three places:

• How fast existing conditions can be measured.
• How safely the fieldwork gets done.
• What lands in the deliverable.

This guide explains the tools, the California and federal rules that apply to them, and what to ask for when you order a survey.

What tools make up the modern surveying toolkit?

Each tool solves a different problem, and most projects use more than one.

• GNSS/RTK positioning. A Global Navigation Satellite System (GNSS) receiver corrected in real time (RTK) by a base station or a reference network can place points at centimeter level under open sky. It ties every other sensor to a known coordinate system. Tree canopy and tall buildings degrade it.
• Robotic total stations. These measure angles and distances optically and still handle the most precise work, such as hardscape, curb lines, and places where satellite signals are blocked.
• Drone (UAS) photogrammetry. An unmanned aircraft system flies a camera in an overlapping pattern. Software turns the photos into an orthomosaic (a scaled, map-accurate aerial image) and a 3D surface. It works best on open, graded, or sparsely vegetated ground.
• Lidar. A lidar sensor fires laser pulses and records their returns. Some pulses pass through gaps in vegetation and reach the ground, which is why lidar can model bare earth where a camera sees only canopy. Under dense brush, ground returns thin out.
• Terrestrial and mobile laser scanning. Tripod- or vehicle-mounted scanners capture dense point clouds of structures, roadways, and building facades. Caltrans publishes terrestrial laser scanning specifications in its Surveys Manual.

Lidar pulses and ground cover

Illustrative diagram — not to scale

1. 1Open ground: a lidar sensor fires laser pulses and records their returns.
2. 2Trees: some lidar pulses pass through gaps in vegetation and reach the ground, which is why lidar can model bare earth where a camera sees only canopy.
3. 3Dense brush: ground returns thin out.

What do these tools actually deliver?

A conventional topographic survey delivers individually measured points and breaklines, from which a surface and contours are modeled. Reality capture adds much denser products:

• Point clouds: millions of georeferenced 3D points, often colored from imagery.
• Surface models: bare-earth terrain models that generate contours, cross sections, and spot elevations.
• Orthomosaics: scaled aerial imagery for planning, permitting exhibits, and records.
• Earthwork volumes: cut, fill, and stockpile quantities computed from repeat captures.

These products feed directly into design. A drone- or lidar-based topographic survey becomes the existing-ground surface for grading plans, and the same survey control later supports construction staking in the field. Keeping one control network from survey through construction avoids a common source of error: design and layout that do not agree on where the ground is.

Who regulates drone survey flights in California?

Two agencies matter most, and they play different roles.

FAA rules

The FAA controls the airspace. Commercial drone work, including surveying, falls under 14 CFR Part 107 for aircraft under 55 pounds. The pilot needs an FAA Remote Pilot Certificate, the drone must be registered, and registered drones must broadcast Remote ID.

Part 107 also sets flight limits. It:

• Requires visual line of sight.
• Generally caps altitude at 400 feet above ground.
• Requires FAA authorization before flying in controlled airspace near many airports.

Temporary flight restrictions, such as those over wildfires, apply to drones too.

Long corridor flights beyond the pilot's line of sight still need an FAA waiver. The FAA proposed a new Part 108 for beyond-visual-line-of-sight operations in August 2025. As of September 2026 no final rule has been published, so survey flights still operate under Part 107.

Caltrans and local rules

Caltrans controls access to state highway right-of-way. According to the Caltrans Division of Aeronautics, the FAA has exclusive authority over drone operations and airspace, but launching, landing, or operating from within State Highway System right-of-way requires a Caltrans encroachment permit.

Requests are considered only for authorized construction work or permitted activities such as surveys, and they go to the local District Encroachment Permits Office under Section 516.9 of the Caltrans Encroachment Permits Manual.

On Caltrans projects, drone use by contractors and consultants may be allowed, but it must be coordinated with the Division of Aeronautics through the Caltrans contract or project coordinator.

Does drone mapping require a licensed surveyor in California?

It requires a licensed professional, either a land surveyor or a civil engineer, not just a certified drone pilot. California's Professional Land Surveyors' Act defines land surveying to include determining "the configuration or contour of the earth's surface, or the position of fixed objects" by applying "the principles of mathematics or photogrammetry" (Business and Professions Code section 8726). The same section covers creating electronic data for that work and making a statement about the accuracy of maps or measured survey data.

The Professional Engineers Act places the same mapping within civil engineering. Section 6731.1 covers determining "the configuration or contour of the earth's surface or the position of fixed objects" by "applying the principles of trigonometry or photogrammetry," along with the related electronic data and accuracy statements. So topographic and photogrammetric mapping may be done by, or under the responsible charge of, a licensed land surveyor or a licensed civil engineer.

Boundary work stays with land surveyors. Maps, plats, descriptions, and other land surveying documents must be prepared by, or under the responsible charge of, a licensed land surveyor or a civil engineer authorized to practice land surveying (section 8761).

Imagery also cannot settle where a property line is. A boundary survey depends on record research and on finding and measuring monuments in the field.

Monuments on road and right-of-way work

Road and right-of-way work adds another rule. Before streets, highways, other rights-of-way, or easements are built, rebuilt, maintained, resurfaced, or relocated, section 8771 requires monuments that control boundaries, roads, or survey control to be located and referenced by or under the direction of a licensed land surveyor (or a civil engineer authorized to practice land surveying), with a corner record or record of survey filed with the county surveyor.

Monuments the work could destroy must be reset or witnessed, with a record filed before the project's certificate of completion is recorded. The government agency doing or permitting the work is responsible for making sure this happens.

How do you know drone or lidar data is accurate?

By testing it against ground truth. The ASPRS Positional Accuracy Standards for Digital Geospatial Data (Edition 2, Version 2, 2024) are the common reference, with addenda for drones, lidar, and photogrammetry.

Under them, checkpoints must be independent of the control used to process the data and at least about twice as accurate as the product being tested. As the U.S. Geological Survey summarizes, a formal accuracy assessment now calls for at least 30 checkpoints, and accuracy in vegetated areas is reported rather than held to a pass/fail threshold.

Coordinates and datums

Coordinates matter as much as checkpoints. California law requires a survey that establishes California Coordinate System (CCS83) values to connect to two or more reference stations, and any map showing CCS83 coordinates must state the datum realization and epoch (Public Resources Code sections 8813.1 and 8815.1).

A datum change is also coming. In May 2026 the National Geodetic Survey (NGS) ended public testing of the replacements for NAD 83 and NAVD 88 (the 2022 terrestrial reference frames such as NATRF2022, the NAPGD2022 geopotential datum for heights, and the State Plane Coordinate System of 2022) and now considers them stable for implementation planning. Until the modernized system is officially released, NAD 83 and NAVD 88 remain the official U.S. datums.

California law already defines a California Coordinate System of 2022 (CCS2022) as the California portion of the State Plane Coordinate System of 2022, and allows new surveys and mapping projects to use it after January 1, 2025. In practice, CCS2022 becomes usable once NGS officially releases SPCS2022. Until then, California surveys continue to use CCS83.

Units

The units change too. The statute specifies the international foot for CCS2022 rather than the U.S. survey foot.

Buried utilities

Finally, aerial methods only see what is visible. Buried utilities need records research, geophysical locating, and sometimes potholing, documented to the quality levels in ASCE 38-22.

How widely do public agencies use drones?

Widely. The Federal Highway Administration says unmanned aircraft systems are now used by transportation agencies in all 50 states, a result it credits to EDC-5, an earlier round of its Every Day Counts program.

Its current round (EDC-8, 2026–2027) moves past basic flights to docked drones for rapid inspections and better handling of large inspection datasets. The same round also promotes subsurface utility engineering and integrated digital project delivery.

The safety case is simple. Capturing a highway shoulder or steep slope from the air, or from a scanner set back from traffic, keeps people out of harm's way.

What this means for your project

• Match the method to the site. Open, graded lots suit drone photogrammetry. Brushy or wooded ground usually needs lidar plus ground shots. Hardscape, utilities, and tight urban sites still lean on total stations and GNSS. Many sites need a mix.
• Ask for the accuracy statement. Request the control and checkpoint results, plus the datum, epoch, and units, in writing with the deliverable.
• Plan for permits near highways and airports. Flights from state highway right-of-way need a Caltrans encroachment permit, and flights in controlled airspace need FAA authorization. Build that lead time into the schedule.
• Do not skip the boundary. If your project involves property lines, easements, or setbacks, a drone map is a supplement to a boundary survey, not a substitute.
• Keep one control network. Use the same control from the existing-conditions survey through design and staking.

Surveys are performed under the responsible charge of a California-licensed land surveyor, as state law requires. If you are scoping a survey and are not sure which methods fit, tell us about your site and what the survey needs to support, and we will help you define the deliverable.