
Related topic: Photogrammetry, Drone Technology,
Mastering Drone Photogrammetry: RTK Simplified Precision
Jan 2025 – Aashutosh Adhikari
Redefining Mapping in the Modern Era
From its rudimentary origins in terrestrial surveying, the craft of mapping has made quantum leaps. From tripods to planes to drones, man has always adapted technology to fit into his way of life and his way of seeing. Central to this revolution is drone photogrammetry, a technology that fuses state-of-the-art imaging systems with top-notch geospatial accuracy.
This case study is one of the early initiative by the Research and Innovation Unit (RIU) at Advanced College of Engineering and Management (ACEM), Nepal. Drones outfitted with Real-Time Kinematic (RTK) capability are a powerful and innovative tool for cost-effective, accurate, and efficient geospatial mapping, and this project that utilizes the DJI Phantom 4 RTK investigates new frontiers in this work.
The Challenge: Precision, Efficiency, and Feasibility
While drone photogrammetry has been successful worldwide, the implementation of this technology also faces various challenges in Nepal:
High Costs of Traditional Surveying: Traditional equipment for surveying is time-consuming, as well as needs an experienced person and a lot of money.
Accuracy Needs in Critical Sectors: High-precision geospatial data (centimeter-level accuracy) is in demand in domains like construction, agriculture, disaster, etc.
Limited Adoption of Advanced Drones: The RTK (real-time kinematic) drones, like the DJI Phantom 4, that are revolutionizing mapping all over the world are a bit out of reach for Nepal due to costs and regulatory hurdles.
A Bold Objective
The project started with lofty goals:
- To promote the practicality of RTK-based drone photogrammetry for accurate mapping.
- Optimized workflows for fast and affordable surveys.
- To explore applications across the industry, from construction and agriculture to academic research.
The Technology Behind the Breakthrough
Drone of Choice: DJI Phantom 4 RTK
This high-end drone has the power of Real-Time Kinematic (RTK) technology for unparalleled geospatial precision.
Key Features
- Camera: 20 MP 1” CMOS sensor + mechanical shutter for distortion-free high-resolution imaging
- Accuracy: Provides centimeter-level accuracy (1.2 cm horizontal and 2 cm vertical), drastically reducing the need for ground control uplink points.
- Flight Performance: 30 minutes of flight time and 50 km/h speed let you rapidly survey large areas.
- Compatible Software: Direct interaction with Agisoft Metashape for photogrammetric processing
The Workflow: A Step-by-Step Approach
- Data Acquisition and Flight Planning
Proper planning is vital for a successful event. Hence, flight paths were designed to have a 75% overlap to attain high data accuracy using the DJI GS RTK app. In a span of 15 minutes, the Phantom 4 RTK captured 417 high-resolution images, optimizing survey output while using the drone’s RTK system to enable centimeter level precision worldwide.
- Data Processing in Agisoft Metashape
The raw images were processed in Agisoft Metashape to obtain detail outputs geospatial. The workflow included:
- Sparse Point Cloud Generation: Corresponding images using common ground points.
- Dense Point Cloud Generation: Generating a 3D representation of the scene for high-definition processing.
- 3D Modeling and Texturing: Creating lifelike, high-resolution 3D figures.
- Orthomosaic Maps and DEMs: Making detailed maps and Digital Elevation Models for analysis.
- Export and Analysis
Outputs including orthomosaic maps and 3D models were exported as PNG and OBJ files respectively. These results come in a form suitable for use in construction, agriculture, and academic studies.

Applications: Revolutionizing Industries
RTK-enabled drones have proven transformative for a multitude of industries:
Construction
- In-depth site surveys and development tracking.
- Graduating project; Producing topographic maps
Agriculture
- Smart farming in terms of crop health monitoring and irrigation strategies.
- Improved pest control for higher gains.
Disaster Management
- Disaster management, such as in swift mapping of affected areas for rescue and resources.
Academic Research
- Environmental Monitoring, Archaeology, and Topography
Challenges and How They Were Overcome
Weather Sensitivity
- Problem: Cloudy weather caused operations impact as Drone is affected and images were not clear
- Solution: Surveys were conducted during favorable weather conditions to ensure workflow.
Battery Management
- Problem: Impose charge restrictions on flight times.
- Solution: The team brought several spare batteries to ensure operations were not interrupted.
Regulatory Compliance
- Problem: Nepal was strict on drone laws and multiple permits were required.
- Solution: Acquired all permits and adhered to guidelines strictly.
Overlap and Coverage
- Problem: 75% overlap meant more flight time and therefore more effort.
- Evidence: Pre- and post-flight analysis of flight metrics.
SWOT Analysis
Strengths
- Workflows enabled with centimeter-level accuracy.
- Ability to work across industries and sectors.
Weaknesses
- High capital expenditure and limited battery lifespan.
- You rely on good weather and a dry season.
Opportunities
- For more advanced applications, integration with AI and LiDAR
- Diversification into heritage conservation and ecosystem monitoring.
Threats
- Drone reliability is being given a dent by harsh environmental conditions.
- Various regulatory obstacles and social pushback against new technology.
Future Goals: Beyond the Project

This project underscored the value of careful planning, including details about weather conditions, flight paths, and battery management for which all factors integral to success. Cooperation among operators and stakeholders also contributed greatly to the success of these operations and site set-ups. Furthermore, utilizing advanced tools like the DJI Phantom 4 RTK delivered unparalleled accuracy and efficiency, underscoring the importance of using the latest technology in the field. In the future, the success of the project in the valley will pave the way for its applications to be wider in the scope of industrial expansion in agriculture, construction and disaster management in addition to preservation of cultural heritage and digital archive of the monuments in Nepal, educational outreach on building local capacities, and the use of photogrammetry integrated with AI and LiDAR for unlocking its potential across the horizontal fields
Conclusion: Unlocking New Horizons with RTK Drones
This project demonstrated the necessity of thorough planning, namely surrounding weather conditions, flight paths, and battery management, as these were all pivotal to its success. Team work also contributed heavily towards execution with operators and stakeholders working together. Investing in advanced technology, including the DJI Phantom 4 RTK, paid off with unmatched precision and efficiency, validating the use of cutting-edge tools. Moreover, the project’s success paves the way for wider applications as the industry in agriculture, building, and disaster management, is grown, which can pave the path for the digital preservation of Nepal’s monuments in culture, an educational outreach initiative can build local capacity in digital technologies in cultural heritage, integration of photogrammetry with AI and LiDAR can serve as a solution for improving the versatility in their presence in various fields
Special thanks to Sojan Prajapati and Suraj Paudel for their invaluable guidance during the project.
References
DJI. (n.d.). Phantom 4 RTK: Redefine surveying with your drone. Retrieved December 26, 2024, from https://www.dji.com/phantom-4-rtk
DJI Store. (n.d.). DJI Phantom 4 Multispectral in agriculture. Retrieved December 26, 2024, from https://www.djistore.com.my/blogs/blog/dji-phantom-4-multispectral-in-agriculture
Gomez, C., & Purdie, H. (2016). UAV-based photogrammetry and geocomputing for hazards and disaster risk monitoring – A review. Geoenvironmental Disasters, 3, 23. https://doi.org/10.1186/s40677-016-0060-y