While drones have significantly transformed the surveying and mapping industry, traditional topographic (topo) surveys are not entirely replaced by drone surveys. Drones offer several advantages, including rapid data collection, cost-effectiveness, and the ability to access remote or challenging terrain. However, there are situations where traditional topographic surveys are still needed, and the choice between drone and traditional methods depends on project requirements, accuracy, and regulatory considerations. Here are some key points to consider: 

When Drone Surveys Are Suitable: 

1. Large Areas: Drones are highly efficient for surveying large areas quickly. They can cover expansive regions in a fraction of the time it would take traditional methods. 

2. Rapid Data Collection: Drones provide real-time or near-real-time data, making them suitable for applications where speed is essential, such as disaster response or construction progress monitoring. 

3. Visual Documentation: Drones capture high-resolution imagery, providing visual documentation of the site, which can be useful for project progress tracking and stakeholder communication. 

4. Safety: Drones eliminate the need for surveyors to work in hazardous or hard-to-reach areas, enhancing safety on construction sites or in challenging environments. 

5. Budget Constraints: Drones are often more cost-effective than traditional surveying methods, making them an attractive choice for projects with budget constraints. 

When Traditional Topographic Surveys Are Necessary: 

1. High Accuracy Requirements: Traditional surveying methods, including total stations and terrestrial LiDAR, can provide higher accuracy than most drones. If a project requires extremely precise measurements, traditional methods may be necessary. 

2. Regulatory Approval: In some regions, regulatory authorities may require traditional surveying methods for certain projects, particularly those related to land boundaries, cadastral surveys, or legal purposes. 

3. Complex Sites: For sites with complex structures, underground utilities, or dense vegetation, traditional surveying methods may be better at capturing detailed data. 

4. Underground and Indoor Surveys: Drones are limited to capturing data from the air and may not be suitable for underground or indoor surveys. Traditional surveying methods are essential for these situations. 

5. Permanent Control Points: Traditional surveys establish permanent control points that provide reference for future surveys. These control points are critical for maintaining long-term accuracy and consistency. 

In many cases, a combination of both drone surveys and traditional topographic surveys is the most effective approach. Drone surveys can be used for initial data collection, rapid assessments, and broad area coverage, while traditional methods can be employed for areas or tasks requiring higher precision. The choice of surveying method should be based on the project’s specific requirements, budget, and the desired level of accuracy. Additionally, it’s essential to consider local regulations and standards that may influence the surveying approach.