Comparing 7 Items: Sites Suited and Unsuitable for Drone Surveying

Drone surveying has become widely used as a method that easily captures large areas in a short time and can represent terrain and site conditions as surfaces. However, it does not perform equally well at every site. Depending on site conditions, it can greatly improve efficiency at some locations, while at others it may fail to provide the expected accuracy or safety, causing rework or re-surveying.

What matters for practitioners is not to judge drone surveying as universally superior, but to determine in advance whether it truly suits their site. A wrong adoption decision can lead to problems such as having usable flight imagery but unusable deliverables, needing to add alternative methods because the site conditions are incompatible, or missing schedule deadlines. Conversely, if suitability is correctly judged, you can efficiently obtain deliverables of the required quality while reducing on-site burden.

This article compares sites suited and unsuited to drone surveying across seven practical items. Rather than merely labelling sites “suitable” or “unsuitable,” we explain why each judgment is made, which conditions are workable, and when to consider combining methods. This is useful not only for those considering adoption but also for those already using drones who are unsure how to choose methods by site.

Table of Contents

• Why you should first determine whether a site is suitable for drone surveying

• Comparison item 1 Area and work extent

• Comparison item 2 Terrain undulation and elevation differences

• Comparison item 3 Trees, structures, and aerial conditions

• Comparison item 4 Surrounding environment and ease of ensuring safety

• Comparison item 5 Required accuracy and strictness of as-built verification

• Comparison item 6 Types of deliverables needed and their uses

• Comparison item 7 Schedule, weather, and operational structure

• Ways to make use of drones even on unsuitable sites

• Summary

Why you should first determine whether a site is suitable for drone surveying

A major strength of drone surveying is the ability to efficiently capture the entire site from above. Unlike traditional ground surveys that pick up data at points, drone surveys make it easier to grasp information as surfaces, so they are especially effective for land development sites, earthwork sites, quarries, management of embankments and cut slopes, and broad area condition assessments. It is also attractive that drones can relatively safely capture situations in high or difficult-to-access locations.

However, being able to view a site from above does not necessarily mean you can reliably produce the required deliverables. Even at sites that are easy to view from above, heavy canopy or structural shadows can prevent sufficient capture of ground-surface information. Or, although image acquisition itself may be fine, the required accuracy may be too strict for the results to meet management standards as-is. In residential areas or places with heavy traffic, ensuring safety and considering surrounding parties can become a significant burden, complicating work planning.

In short, success or failure of drone surveying is not determined solely by aircraft performance. Site conditions, objectives, required accuracy, surrounding environment, and operational structure must align for effectiveness. Therefore, in practice you should not start with “Can we use a drone?” but with “At this site, what do we want to obtain, to what accuracy, and at what stage?”

A particular caution is not to regard drone surveying as a single panacea. While highly effective at suitable sites, if even one unsuitable condition is strongly present, combining ground surveys or supplementary measurements is often more rational overall. Below we examine seven items that directly inform that judgment.

Comparison item 1 Area and work extent

Drone surveying tends to be most effective where there is a reasonably large, contiguous area and you want to understand it as a surface. For planned development sites, large sites that require earthwork volume management, broad terrain checks including slopes, temporary stockpile quantity assessment, or wide-area progress monitoring, it is easier to grasp the whole picture in a short time than to walk and measure in detail from the ground. The larger the site, the more travel time and effort to ensure sightlines increase relatively, so the advantage of capturing from the air at once becomes more apparent.

Conversely, drone surveying tends to be unsuitable for sites where the target area is extremely small and the purpose is only localized checks. For example, verifying the positions of a limited number of points, measuring dimensions in very narrow areas, or partial as-built checks can make the entire sequence of flight preparation, safety checks, securing takeoff and landing areas, and post-processing disproportionately burdensome relative to the measurement target. As a result, for some sites it is faster and more reliable to measure directly from the ground.

The important point here is not to judge by simple area alone. Even on a large site, if what you need is a single local point or a check of one side, the drone’s strengths are less applicable. Conversely, on a medium-sized site, if you need continuous surface information such as overall elevation differences, current shape, earthwork volumes, or progress comparisons, drone surveying fits well.

Also be cautious when the work area is fragmented. Even if the total area seems large, if the targets are divided into multiple small plots separated by roads, buildings, or restricted zones, operations become inefficient. You will have to split flight plans finely, and safety checks and movement burdens increase. In such cases, the key criterion is whether the area can be captured as a continuous extent, rather than area alone.

In practice, sites suited to drone surveying are not only large but have contiguous areas where capturing the whole surface is valuable. Unsuitable sites are those where the target is narrow, point-like, or fragmented so that flight efficiency is poor. Area is an easy first indicator, but the correct way to think is “it’s suitable because there is a purpose that can take advantage of the area,” not simply “it’s large so it’s suitable.”

Comparison item 2 Terrain undulation and elevation differences

Terrain undulation and elevation differences are representative factors that affect compatibility with drone surveying. Undulating terrain itself is not necessarily a disadvantage. Rather, when a wide area includes elevation differences and ground-level visibility or movement is difficult, the benefit of understanding the whole terrain from above is greater. For sites mixing cut-and-fill, broad terrain including slopes, or mountainous area condition checks, it is more efficient to capture the continuity from the air than to walk the site to get the overall picture.

On the other hand, sites with large elevation differences require attention to flight altitude planning and image quality. The steeper the elevation change, the more the distance to the ground varies by location, making it harder to secure consistent image resolution and overlap. Especially on sites with many slopes and steps, top-down views alone may not fully capture required surfaces, reducing the reproducibility of slope shapes. Therefore, rather than simply deciding that elevation differences make a site suitable or unsuitable, the important thing is whether you can create a flight plan adapted to the terrain changes.

The same applies to slope faces. Drone surveying is effective for capturing wide slope faces, but the ease of obtaining deliverables greatly depends on slope orientation, gradient, terracing, small benches, and vegetation. If the slope surface is clearly visible, surface-shape capture is suitable; but if grass is overgrown or there are protrusions and many shadows, necessary shapes may not be fully captured. What matters in measuring slopes is not merely the presence of a slope but whether that slope can be stably captured as aerial imagery.

Also, valley-like terrain or deep excavations are prone to creating blind spots when viewed from above. Even though aerial capture excels at overall understanding, near-vertical faces, recessed parts, and upturns adjacent to structures may be poorly represented. In such cases, consider ground-based supplementary measurements or capturing from different angles to stabilize deliverable quality.

In short, drone surveying suits sites where, even with elevation differences, capturing the entire area as a surface is valuable and where acquisition plans can be tailored to terrain changes. Unsuitable sites are those that are steep with many blind spots so necessary surfaces are not adequately visible, or sites whose main purpose is precise checks of localized vertical upturns or fine details. Elevation differences are not inherently a weakness of drones; they can be a strength or a weakness depending on planning.

Comparison item 3 Trees, structures, and aerial conditions

A decisive factor for drone surveying success is how directly the target can be viewed from above. Open ground or earthwork sites where the ground surface is exposed and few obstructions exist are highly suitable for drone surveying. It is easy to extract ground surface shape from images and create surface deliverables, and the higher the aerial visibility, the more stable the post-processing tends to be.

Conversely, sites with many trees are a typical example where drone surveying is unsuitable. From above you mostly see crowns, and the underlying ground or fine terrain is often invisible. In dense forests or scrub, tall grass, or slopes covered by vegetation, even if images are captured, you may not obtain the ground information required in practice. While such imagery can be useful as current-condition photos, accuracy for terrain surveying or volume estimation may be insufficient, so you need to separate intended purposes and deliverables.

Sites with many structures also require caution. In locations with dense buildings, lots of scaffolding or temporary materials, under bridges or roofs, or where equipment is densely installed, sightlines from above deteriorate and shadows and blind spots increase. Especially the areas around buildings and structural upturns tend to be inadequately represented by aerial photos alone, limiting accurate 3D capture. Additionally, aerial obstacles and proximity to surrounding facilities impose constraints, reducing freedom of capture.

Aerial conditions must not be overlooked. Power lines, communication equipment, cranes, and overhanging trees increase flight-path constraints. These not only pose hazards but can limit flight altitude and angles, making it difficult to obtain necessary images. In practice people tend to only check whether flight is possible, but the real question is whether you can obtain the required quality. Even if flight is safe, if stable capture at the necessary directions or altitudes is impossible, the value of the deliverables diminishes.

Therefore, drone surveying suits sites where the ground is easily visible, obstructions are few, and aerial conditions are relatively simple. Unsuitable sites are those where ground is easily hidden by trees or structures, or where many aerial constraints make necessary flight plans difficult. In such conditions it is realistic to limit drone use to condition assessment or record-keeping and supplement precise shape capture or positional checks with other methods.

Comparison item 4 Surrounding environment and ease of ensuring safety

In drone surveying, not only the target itself but the surrounding environment greatly affects operational difficulty. For example, sites with few unauthorized visitors, where takeoff and landing areas are easy to secure and sufficient distance from surroundings can be maintained, make planning and safety management straightforward and are suited to drone surveying. Development sites, large material yards, and construction sites with clearly defined management areas often meet these conditions.

Conversely, proximity to residential areas, busy roads, locations with many pedestrians, or places where heavy machinery or vehicles operate frequently raise the difficulty of ensuring safety. Assigning safety personnel, managing access, adjusting flight paths, and restricting work hours tend to increase preparatory work beyond the surveying itself. As a result, at some sites the burden of safety measures can exceed the effort of flying.

In practice you also need to consider the psychological impact on surrounding people, not just flight permissibility. Near people or buildings, noise and visual privacy concerns, providing explanations to avoid misunderstandings and anxiety, and coordination among stakeholders are essential. At sites requiring such considerations, operation may be technically possible but the operational burden may be heavy, leading to a decision that drone surveying is unsuitable.

From a safety perspective, takeoff and landing conditions are also important. Sites with ample space and adequate clearance from surrounding obstacles are easier to operate, whereas confined sites or those with scattered materials increase pre- and post-flight risks. Furthermore, if you cannot completely stop third-party movement within the site, executing the planned flight becomes difficult. Time estimation becomes uncertain and can affect the schedule.

In short, sites suited to drone surveying from the standpoint of surroundings and safety are those where the work area is easy to manage, there is little interference from third parties, and safety arrangements are straightforward. Unsuitable sites are those where the burden of managing surrounding parties, traffic, and access is large and organizing non-flight conditions is excessively time-consuming. Do not judge only by technical feasibility; considering the overall operational burden leads to decisions that avoid failures.

Comparison item 5 Required accuracy and strictness of as-built verification

When introducing drone surveying, the accuracy question is what most people worry about. What matters is not considering how accurate drone surveying can be in general, but clarifying the accuracy required at the specific site. For purposes such as condition assessment, progress confirmation, rough earthwork volume estimation, or broad shape checks, the rapid acquisition of surface data itself has great value. Drone surveying is very compatible with such objectives.

However, for strict as-built verification subject to tight management standards, or situations where small dimensional differences must be reliably judged, careful consideration is necessary. Deliverables derived solely from aerial imagery are susceptible to site and processing conditions and can be uncertain at local edges, around structures, upturns, and occluded areas. Therefore, the higher the required accuracy, the more prudent it is to assume combinations with control-point management and ground checks rather than relying solely on drone data.

Accuracy involves not only planimetric position but also elevation precision. For earthwork calculations and grading verification, stability of height information is important, but results can vary depending on ground visibility, shadows, shooting conditions, and the surface state. Especially where surfaces are non-uniform, grass remains, or puddles exist, evaluation can be harder than it appears.

A common practical misunderstanding is the binary view that “drone surveying therefore has low accuracy” or “ground surveying therefore must be high accuracy.” In reality, if you can plan and validate according to the objective, drone surveying can be highly effective; conversely, any method produces unstable results if used for inappropriate purposes. The important thing is to clarify the required accuracy, determine the range you want to guarantee, and predefine where to perform supplementary checks.

Therefore, drone surveying suits sites where the main purpose is surface comprehension or broad trend checks and where key confirmations can be supplemented by other methods. It is unsuitable where the primary purpose is precise measurement of local dimensional differences or strict as-built determinations and where occlusions and blind spots are many. Accuracy should be judged not mechanically but by how you will ensure the required quality, which reduces adoption mistakes.

Comparison item 6 Types of deliverables needed and their uses

An often-overlooked perspective when judging suitability is “what will you ultimately use as a deliverable?” Lumping everything under the term “survey” makes it easy to make the wrong choice. If your goal is site photos, orthophotos, surface understanding, earthwork volume management, progress comparisons, or creating a simple 3D model, drone surveying is very effective. Its ability to capture wide areas at once and to repeatedly acquire under the same conditions for comparisons is a major advantage.

Conversely, if your main goals are detailed dimensional checks, accurate shape capture around structures, indoor or under-roof assessments, or verification of underground or hidden parts, drones alone are less suitable because aerially accessible information does not match the practical information needed. For example, imagery may be adequate for explaining current conditions but insufficient as detailed dimensions required for design changes. Overlooking this mismatch can lead to post-capture complaints that “the deliverable is not what we wanted.”

Also be cautious about adopting a “let’s just fly for now” approach without clarifying how deliverables will be used. Even if data is collected, if internal use cases are not established, benefits relative to on-site burden may be unclear. Conversely, if use cases such as construction management, progress sharing, client explanations, volume checks, or coordination with design are clear, it becomes easier to determine acquisition methods and required quality.

In practice, drone surveying succeeds more often when the types of deliverables and their uses align. If used for wide-area condition sharing or regular comparisons, the ability to repeatedly capture from the same viewpoint is a strong point. But when strict management of lines or points is required, surface data from above is often insufficient.

Thus, sites suited to drone surveying are those where aerial images and surface terrain information directly support decision-making and management. Unsuitable sites focus on precise detail checks or hidden areas where aerial data alone is insufficient for practical decisions. Before adoption, decide first what you will use the deliverables for, not just what you can capture.

Comparison item 7 Schedule, weather, and operational structure

Drone surveying is often expected to shorten schedules because on-site acquisition appears quick. Indeed, it can be highly effective for quickly capturing wide sites. However, when looking at the entire schedule you must consider pre-flight preparations, stakeholder coordination, safety checks, post-acquisition processing, and deliverable verification. Sites where this entire sequence can be accommodated without strain are suited to drone surveying.

For example, when the work schedule has some buffer, weather-related rescheduling is possible, and site cooperation is readily obtained, drone surveying tends to deliver results. For continued fixed-point observation or progress comparisons, establishing operational rules leads to stable results. If you have a system that covers not only capture but also subsequent processing and sharing, drone surveying can be a very effective means of site improvement.

On the other hand, if the schedule is tight, re-shooting is not allowed, and the site is highly weather-sensitive, caution is needed. Wind, rain, and lighting conditions can affect acquisition quality, so you must always consider the possibility that the planned flight may not be possible. Moreover, even if flight is possible, if subsequent data processing or verification takes time, it may not meet site decision timelines. Cases exist where adoption intended to shorten schedules fails to raise overall efficiency because follow-up processes cannot keep up.

Operational structure is also important. Drone surveying is not established merely by being able to fly. The more clearly defined are what to capture, under what conditions, how to verify, and who will use which deliverables, the easier it is to integrate into practice. Conversely, heavy reliance on individual operators and inconsistent judgments by site increase deliverable variability and rework.

From this viewpoint, sites suited to drone surveying have schedule flexibility, can incorporate weather risks, and can establish systems that include post-processing and utilization. Unsuitable sites are those where there is no leeway for weather, immediate and strict on-site decisions are required, and re-acquisition is difficult. Even with technical capability, outcomes are unstable without supporting operational structure. When introducing drones at a site, design not only the aircraft and shooting methods but also internal operational procedures.

Ways to make use of drones even on unsuitable sites

So far you may feel that if one unfavorable condition exists, drone surveying cannot be used. In reality, even at unsuitable sites, restricting how you use drones can still provide significant value. The key is not trying to complete everything with the drone alone.

For example, at heavily treed sites that are not suitable for ground-surface capture, drones are still useful for recording current-condition photos and sharing with stakeholders. At sites with many structures where detailed capture is difficult, drones help grasp overall layout and provide an aerial overview of progress. Even if drones are not suitable for strict as-built verification, they can be used for before-and-after comparisons or visualizing work extents. In other words, “unsuitable” does not mean “unsuitable for all purposes”; it means “less effective unless the purpose is limited,” which is a practical way to understand it.

Combining with ground surveys is also highly effective. Capture overall surface information from the air and supplement critical points or blind spots on the ground—this approach leverages the strengths of both methods. This can be more efficient than relying entirely on ground surveys, while improving deliverable quality compared to drones alone.

Furthermore, for on-site positioning and supplementary positioning tasks, high-precision ground position checks are important in addition to aerial data. In such cases, combining with iPhone-mounted GNSS high-precision positioning devices such as LRTK makes it easier to perform on-site supplementary checks and locate key points. The workflow of capturing the whole site by drone and supplementing on the ground with high-precision position data matches practice well. Understanding the strengths and weaknesses of drone surveying and preparing ground-side methods as needed leads to practical and manageable operations.

Summary

Whether a site is suited to drone surveying is not determined simply by whether it is large or small, or whether flight is possible. Organizing considerations across seven perspectives—area and work extent, terrain undulation, trees and structures, surrounding environment and safety, required accuracy, types and uses of deliverables, and schedule and operational structure—makes site-specific suitability clearer.

Suitable sites are those where you want to capture broad contiguous areas as surfaces, where the ground is easily visible, where surroundings are easy to manage, and where aerial data is valuable for condition assessment or progress monitoring. Unsuitable sites are those with many obstructions, those focused on localized precise checks, those where safety management burden is excessive, or those with too-strict weather or schedule constraints. However, unsuitable conditions do not mean drones cannot be used at all—limiting purposes or combining with ground measurements often enables effective use.

To avoid failures in practice, do not make drone introduction an end in itself. First decide what you want to capture, what accuracy is required, and who will use the deliverables. Then, assigning overall roles—drones for overall capture and ground positioning for high-precision checks—makes it easier to create site-appropriate operations. If you want to link drone-acquired information to on-site positioning or supplementary measurements, using iPhone-mounted GNSS high-precision positioning devices such as LRTK can help secure ground-side accuracy and ease operations. Judging the suitability of drone surveying is not just equipment selection but a decision to optimize the entire site.