Thursday, September 18, 2025

 OpenDroneMap (ODM) is a powerful open-source toolkit designed to transform aerial imagery—particularly from drones—into rich geospatial data products. At its core, ODM performs photogrammetric processing, converting overlapping images into 3D models, orthophotos, point clouds, and digital elevation models (DEMs). It achieves this through a multi-stage pipeline that includes structure-from-motion (SfM), multi-view stereo (MVS), meshing, texturing, and georeferencing. The analytical engine behind ODM is modular and extensible, allowing users to tailor workflows to specific datasets and mission goals. 

The processing begins with image alignment using OpenSfM, which detects and matches features across multiple images to reconstruct camera positions and sparse 3D points. This is followed by dense reconstruction using MVS techniques, which generate detailed point clouds. These points are then filtered and meshed to create surface models, which are textured using the original imagery. Georeferencing is supported through ground control points (GCPs), RTK metadata, or GPS tags, enabling accurate spatial alignment with real-world coordinates. ODM also supports multispectral and thermal imagery, expanding its utility beyond visible-spectrum applications. 

One of the most user-friendly interfaces to ODM is WebODM, a browser-based front end that simplifies dataset management, processing configuration, and visualization. WebODM includes tools for measurement, volume calculation, annotation, and export to GIS platforms. It also supports plugins and scripting for advanced users, and can be deployed via Docker for cross-platform compatibility. 

Applications of OpenDroneMap span a wide range of domains. In agriculture, it’s used for crop mapping, health monitoring, and precision farming. In construction and mining, ODM enables site planning, stockpile volume estimation, and progress tracking. Environmental researchers use it for forest canopy analysis, erosion modeling, and habitat mapping. Urban planners and surveyors rely on ODM for land use classification, infrastructure inspection, and topographic modeling. It’s also employed in disaster response for damage assessment and terrain reconstruction, and in archaeology for site documentation and 3D reconstruction of historical landscapes. 

ODM’s scalability is notable—it supports both small teams and large-scale operations. For high-performance computing environments, modules like ClusterODM and NodeODM allow distributed processing across multiple machines. The system is designed to accommodate varying hardware capabilities, with memory-efficient features like split-merge processing and support for low-bandwidth deployments. 

In terms of technique, ODM emphasizes reproducibility and transparency. Its open-source nature allows researchers and developers to audit, extend, and integrate its algorithms into broader workflows. It supports standard geospatial formats and integrates seamlessly with tools like QGIS, Potree, and Cesium for visualization and analysis. The community around ODM is active and collaborative, contributing improvements, translations, and documentation that make it accessible to users across disciplines and geographies. 

OpenDroneMap is not just a photogrammetry engine—it’s a comprehensive geospatial processing ecosystem. Its combination of technical rigor, modular design, and broad applicability makes it a cornerstone tool for drone-based mapping and analysis across agriculture, construction, conservation, and beyond 

The difference between OpenDroneMap and the videoprocessing  capabilities of the proposed platform2 is that OpenDroneMap requires 65% overlap between aerial images and this platform does not but that said this platform allows the use of OpenDroneMap to extend analytics. 

#codingexercise: https://1drv.ms/w/c/d609fb70e39b65c8/EWseE3IadyhIhRLFiwKXBroBHcZnR7kzW_smxWoWR4y-UQ?e=D3hYRG

Wednesday, September 17, 2025

 UAV Swarm Graphs 

Graph models offer a powerful abstraction for representing UAV swarm behavior, especially in a decentralized and autonomous computing framework. In this paradigm, each drone is a node, and edges represent communication links, navigational paths, or coordination dependencies. The document outlines several key graph operations that underpin swarm functionality and each of these are candidates for migrating or extending to the cloud to democratize analytics-based feedback loop for FPV drones of all types and capabilities and reduce costs. 

1. Graph Construction and Validation 

   The UAV Map Graph Module constructs a navigational graph from user-defined specifications, typically encoded in JSON. Nodes represent waypoints or drone positions, while edges define permissible flight paths. Cycle detection and removal ensure that drones avoid infinite loops during mission execution. This operation is foundational for route planning and swarm-wide path coherence. 

2. Mission Scheduling and Image Routing   

   The scheduling module overlays mission objectives onto the graph, assigning tasks to specific nodes and orchestrating image capture and retrieval. This enables spatially distributed task execution, where drones traverse graph edges to complete localized missions and relay data back to the cloud. 

3. Gossip-Based Communication   

   The gossip transmission algorithm facilitates decentralized communication by propagating state updates and telemetry across the swarm. Graph topology determines transmission paths, and validation ensures that the gossip protocol maintains consistency and avoids bottlenecks or dead ends. 

4. Image Processing and Geospatial Mapping   

   Captured images are tagged to graph nodes and processed for object detection, classification, and georeferencing. This creates a spatially indexed dataset that reflects the swarm’s coverage and environmental interactions. 

The public cloud, say Azure offers support for Graph-based UAV operations with a rich suite of services at scale. These include CosmosDB that is ideal for storing and querying graph data, and supports property graphs and traversal operations. UAV nodes and edges can be modeled as vertices and relationships, enabling efficient pathfinding, cycle detection, and mission mapping. OpenDroneMap can provide functionalities for processing aerial imagery and serverless tools can handle common routines such as processing customizations, mission scheduling, gossip propagation, and image routing. They enable event-driven execution, allowing drones to trigger cloud workflows based on graph state changes. Azure Stream Analytics and Event Hubs can support real-time ingestion and processing of telemetry data. Graph-based communication patterns can be monitored and optimized using streaming queries, ensuring swarm responsiveness and fault tolerance. For geospatial graph operations, Azure Maps can overlay graph nodes onto terrain data, while Spatial Anchors can help drones localize themselves within the graph using visual cues and GPS data.  Finally,  Graph neural networks (GNNs) can be trained to predict optimal paths, detect anomalies in communication patterns, or infer missing links in the swarm topology. These models can be deployed via Azure ML pipelines and updated continuously with new mission data. 

#codingexercise: CodingExercise-09-17-2025.docx

Tuesday, September 16, 2025

 In the evolving landscape of autonomous aerial systems, coordinating UAV swarms in dynamic environments presents a formidable challenge. Traditional centralized control models often struggle with scalability and adaptability, especially when navigating complex terrains or responding to unpredictable obstacles. To address this, a promising approach involves blending Self-Organizing Maps (SOMs) with Deep Q-Networks (DQNs)—a hybrid architecture that leverages unsupervised spatial abstraction alongside reinforcement-driven decision-making.

At the heart of this system lies a decentralized swarm of UAV agents, each equipped with onboard sensors to capture environmental data such as terrain features, obstacle proximity, and traffic density. This raw data is first processed through a SOM, which clusters high-dimensional inputs into a topological map. The SOM acts as a spatial encoder, reducing complexity and revealing latent structure in the environment—essentially helping each UAV “see” the world in terms of navigable zones, threat clusters, and flow corridors.

Once the SOM has abstracted the environment, its output feeds into a Deep Q-Network. The DQN uses this simplified state representation to learn optimal actions—whether to move, rotate, ascend, or hold position—based on a reward function tailored to swarm objectives. These objectives include maintaining formation integrity, avoiding collisions, minimizing energy consumption, and maximizing throughput through constrained airspace. The reward engine dynamically adjusts feedback based on real-time metrics like deviation from formation, proximity to obstacles, and overall swarm flow efficiency.

A key advantage of this hybrid model is its ability to support leader-follower dynamics within the swarm. The SOM helps follower UAVs interpret the leader’s trajectory in context, abstracting both environmental constraints and formation cues. This enables fluid reconfiguration when conditions change—say, a sudden wind gust or a moving obstacle—without requiring centralized recalibration. The SOM re-clusters the environment, and the DQN re-plans the agent’s next move, all in real time.

To evaluate the system, simulations can be run in urban grid environments with variable wind, dynamic obstacles, and no-fly zones. Metrics such as formation deviation, collision rate, and flow efficiency provide quantitative insight into performance. Compared to vanilla DQN models or rule-based planners, the SOM-DQN hybrid is expected to demonstrate superior adaptability and throughput, especially in congested or unpredictable settings.

Technically, the system can be implemented using Python-based SOM libraries like MiniSom, paired with PyTorch or TensorFlow for the DQN. Simulation platforms such as AirSim or Gazebo offer realistic environments for testing swarm behavior under diverse conditions.

Ultimately, this architecture offers a scalable, intelligent framework for UAV swarm coordination—one that balances spatial awareness with strategic action. By fusing the pattern-recognition strengths of SOMs with the decision-making power of DQNs, it opens the door to more resilient, efficient, and autonomous aerial systems

#Codingexercise: https://1drv.ms/w/c/d609fb70e39b65c8/ESsWUvVzPLFGiT860L8ui-EBYUjcDiDS6duyx957lTSwoA?e=Dtd4Kf

 Deep Q-Networks (DQNs) have emerged as a transformative approach in the realm of autonomous UAV swarm control, particularly for waypoint determination and adherence. At their core, DQNs combine the strengths of Q-learning—a reinforcement learning technique—with deep neural networks to enable agents to learn optimal actions in complex, high-dimensional environments. This fusion allows UAVs to make intelligent decisions based on raw sensory inputs, such as position, velocity, and environmental cues, without requiring handcrafted rules or exhaustive programming. 

In the context of UAV swarms, waypoint determination refers to the process of selecting a sequence of spatial coordinates that each drone must follow to achieve mission objectives—be it surveillance, search and rescue, or environmental monitoring. Traditional methods for waypoint planning often rely on centralized control systems or pre-defined trajectories, which can be rigid and vulnerable to dynamic changes in the environment. DQNs, however, offer a decentralized and adaptive alternative. Each UAV can independently learn to navigate toward waypoints while considering the positions and behaviors of its neighbors, obstacles, and mission constraints. 

One of the key advantages of DQNs in swarm coordination is their ability to model the waypoint planning problem as a Markov Decision Process (MDP). In this framework, each UAV observes its current state (e.g., location, heading, proximity to obstacles), selects an action (e.g., move to a neighboring grid cell), and receives a reward based on the outcome (e.g., proximity to target, collision avoidance). Over time, the DQN learns a policy that maximizes cumulative rewards, effectively guiding the UAV through optimal waypoints. This approach has been successfully applied in multi-agent scenarios where drones must maintain formation while navigating complex terrains. 

For example, Xiuxia et al. proposed a DQN-based method for multi-UAV formation transformation, where the swarm adapts its configuration from an initial to a target formation by learning optimal routes for each drone. The system models the transformation as an MDP and uses DQN to determine the best movement strategy for each UAV, ensuring collision-free transitions and minimal energy expenditure. Similarly, Yilan et al. implemented a DQN-driven waypoint planning system that divides the 3D environment into grids. Each UAV selects its next move based on DQN predictions, optimizing path efficiency and obstacle avoidance. 

To enhance learning efficiency, modern DQN implementations often incorporate techniques like prioritized experience replay and target networks. Prioritized experience replay allows UAVs to learn more effectively by focusing on experiences with high temporal difference errors—those that offer the most learning value. Target networks stabilize training by decoupling the Q-value updates from the current network predictions, reducing oscillations and improving convergence. 

Moreover, DQNs support scalability and robustness in swarm operations. Because each UAV learns independently using local observations and shared policies, the system can accommodate large swarms without overwhelming communication channels or computational resources. This decentralized learning paradigm also enhances fault tolerance; if one UAV fails or deviates, others can adapt without compromising the entire mission. 

In real-world deployments, DQN-based swarm control has shown promise in dynamic environments such as urban landscapes, disaster zones, and contested airspaces. By continuously learning from interactions, UAVs can adjust their waypoint strategies in response to changing conditions, such as wind patterns, moving obstacles, or evolving mission goals. 

There is speculation that self-organizing maps (SOM) can be integrated with DQN where UAV swarm must optimize formation under environmental constraints. SOMs can preprocess high-dimensional state spaces into simplified input for Q-network, cluster environmental features such as terrain obstacles, traffic density, to guide UAVs towards optimal formations, improves exploration efficiencies by identifying promising regions in the state-action space. When combined with Multi-agent Reinforcement Learning (MARL) for decentralized decision-making and GNN for modeling inter-agent relationships and spatial topology, MARL-SOM-GNNs architecture enables a UAV swarm to dynamically adapt formation based on clustered environmental features, maximize flow and coverage in constrained environments and maintain robust co-ordination even with partial observability or noisy data.  

Finally, Deep Q-Networks offer a powerful, flexible, and scalable solution for UAV swarm waypoint determination and adherence. By enabling autonomous learning and decision-making, DQNs pave the way for intelligent aerial systems capable of executing complex missions with minimal human intervention. 

Sunday, September 14, 2025

 Boids algorithm 

The Boids algorithm, originally developed by Craig Reynolds in 1986, is a computational model that simulates the flocking behavior of birds through three simple rules: separation (avoid crowding neighbors), alignment (steer towards the average heading of neighbors), and cohesion (move toward the average position of neighbors). Though deceptively simple, these rules give rise to complex, emergent group behaviors that have inspired a wide range of applications—including the coordination of Unmanned Aerial Vehicles (UAVs). 

 

In the context of UAV operations, especially in swarm scenarios, the Boids algorithm offers a biomimetic approach to decentralized control. Traditional UAV control systems rely heavily on centralized Ground Control Stations (GCSs) or direct remote control, which become increasingly inefficient and fragile as the number of drones scales up. Communication bottlenecks, latency, and the risk of packet loss can severely compromise mission success. The Boids model, by contrast, enables each drone to act autonomously based on local information, reducing reliance on centralized coordination and enhancing robustness. 

 

Recent research has demonstrated the viability of Boids-inspired algorithms for UAV formation control and obstacle avoidance. For instance, Lu et al. proposed a Boids-based integration algorithm that allows UAVs to autonomously switch between formation mode and obstacle avoidance mode depending on environmental stimuli. In formation mode, drones use a virtual structure method to maintain their positions relative to the group, while in obstacle avoidance mode, they employ artificial potential fields to navigate safely around hazards. This dual-mode flexibility ensures that UAV swarms can adapt dynamically to changing conditions while maintaining mission integrity. 

 

Moreover, the Boids algorithm has been successfully implemented in real-world UAV systems using platforms like the Robot Operating System (ROS). Hauert et al. created a flock of ten drones that mimicked Boids behavior both in simulation and physical flight, although with some limitations in separation due to altitude constraints. Braga et al. extended this work by developing a leader-following Boids-inspired algorithm for multi-rotor UAVs, demonstrating its effectiveness in both simulated and real environments. 

 

One of the most compelling advantages of Boids-based UAV control is its scalability. Because each drone only needs to consider its immediate neighbors, the system can scale to hundreds or even thousands of units without overwhelming computational or communication resources. This makes it particularly suitable for applications like search and rescue, environmental monitoring, and large-scale aerial displays, where coordinated movement and adaptability are crucial. 

 

The integration of Boids with reinforcement learning (RL) further enhances its capabilities. In pursuit-evasion scenarios, for example, researchers have combined Boids principles with deep RL algorithms to enable drones to learn optimal strategies for tracking or evading targets in complex environments. The Boids-PE framework, hosted on GitHub, exemplifies this hybrid approach by merging Boids dynamics with Apollonian circle strategies for multi-agent coordination. 

 

In summary, the Boids algorithm provides a powerful, nature-inspired framework for decentralized UAV swarm control. Its simplicity, adaptability, and compatibility with modern AI techniques like reinforcement learning make it a cornerstone for next-generation autonomous aerial systems. As drone operations continue to expand in scale and complexity, Boids-based models offer a promising path toward resilient, intelligent, and cooperative UAV behavior. 

#codingexercise: https://1drv.ms/w/c/d609fb70e39b65c8/EQGR4XYzmvZEmwbmoTdjGrIBx4VlAyGgQBvFINYcN9VsDw?e=w56OXU