During the ESA HOTOSM Validation Fellowship, my journey began with the basics—learning how to install JOSM on my laptop and understanding its interface. From there, I learned how to install and use essential plugins such as the Building Tools plugin, Utils plugin, Mapathoner, and other supporting tools that greatly improved my workflow and actually made my validation easy. I also learned how to install and apply map paint styles, which helped me easily detect issues such as overlapping buildings and missing or incorrect tags, learnt how to work with different imagery such as bing, Esri and how to deal with the imagery offsets. These foundational steps laid the groundwork for my growth as a validator and deepened my understanding of data quality in OpenStreetMap. As the fellowship progressed, we moved into active validation, where I gradually became familiar with new JOSM shortcuts that made mapping and validation more efficient. Shortcuts such as B for drawing buildings, G for ungluing objects, and Ctrl + Shift + G for replacing the geometry significantly improved my speed and accuracy. As someone who had not done validation before, the daily practice sessions were extremely valuable. Validating tasks across different regions allowed me to learn by doing, and with each task, my confidence and skill level improved. This consistent hands-on practice reinforced the idea that practice truly makes perfect.

One of the most impactful aspects of the fellowship was the opportunity to receive personal guidance. I had several private sessions with some of the team members, where I received direct feedback, clarification on complex validation issues, and encouragement to keep improving. These sessions helped me better understand quality standards, common mapping mistakes, and how to communicate effectively with mappers. Through this mentorship and continuous practice, I grew from a beginner in validation to someone who is now confident in reviewing and improving mapping data.

Throughout the fellowship, I also validated data across different regions, including Africa and other parts of the world. This exposed me to variations in settlement patterns, building shapes, and infrastructure layouts. By using filters, imagery tools, and map paint styles, I was able to identify inconsistencies such as overlapping polygons, misaligned features, and missing attributes. This experience gave me a broader perspective on how global mapping standards are applied in diverse geographical contexts and strengthened my attention to detail as a validator.

Balancing the fellowship with my academic responsibilities was sometimes challenging, as the training period overlapped with my lectures and examinations. However, the availability of recorded sessions ensured that I could catch up whenever I missed a live session. This flexibility allowed me to remain consistent and committed throughout the program. To further enhance the fellowship experience, I would suggest more flexible scheduling and additional interactive sessions to encourage stronger connections among fellows.

My name is Justus Aikiriza, a passionate mapper and Land Surveying and Geomatics Engineering student from Uganda. I joined HOTOSM with the desire to make a meaningful humanitarian impact through mapping. Through this fellowship, I have not only gained strong technical validation skills but also built confidence in my ability to contribute high-quality OpenStreetMap data. Today, I am confident in validation, committed to quality over quantity, and motivated to continue supporting humanitarian mapping initiatives across the ESA region and beyond.

Also adding to my introduction, my first impression was the time I was selected among the people to participate in the fellowship, I got so happy coz I had always waited and wanted this opportunity, so me being chosen among didn’t really take that chance for granted and really appreciate God for this together with Madam Becky Chandu our organizer and the entire HOT fraternity for this wonderful arrangement. By the time I was selected, we were actually in exams buh I had create some time each time to make sure I contribute, ask questions where I didn’t understand coz to me it was an opportunity, and now I have all it takes to actually volunteer as the Validator and mapper. Thank you so much. May God Bless you 🙏🙏