YouthMappers Validation Hub


What is the YouthMappers Validation Hub? 


The YouthMappers Validation Hub is a group of experienced student mappers whose purpose is to ensure a high standard of data quality in the collaborative mapping platform OpenStreetMap (OSM). Formed in May 2019, the Validation Hub was organized and implemented by faculty and students at The George Washington University in Washington, D.C. Our primary focus is to validate the work of OSM contributors and guarantee that all YouthMappers projects have the highest quality data. We are also interested in the behavior of new and current mappers and understand that the only way to enhance contributions is to improve the technique, habits, and conduct of mappers:


  1. Technique - Are mappers properly outlining buildings and roads, adjusting the imagery to match the map geometry, tagging features using update-to-date labels, etc.?

  2. Habits - Do mappers consistently map and tag all identifiable features, leave feedback about their edits, make edits without deleting the work of others, etc.?

  3. Conduct - Are mappers respecting official OSM rules and regulations, leaving appropriate changeset comments, averting vandalising map data, etc.?


Overall, YouthMappers Hub members, commonly referred to as Hub, strive to strengthen the confidence and talents of mappers, the OSM community and volunteers from YouthMapper chapters around the globe. With our efforts, we don’t plan on building just maps or mappers, we also build validators. 

From YouthMapper’s 3rd Quarterly Newsletter: GWU Geography launches the YouthMappers Validation Hub! 

In June 2019, a small cohort of validators began reviewing projects and edits made by YouthMappers on OpenStreetMap (OSM). The primary focus of the validation hub is to retroactively validate mapping activities and create a strategic workflow for monitoring #YouthMappers tasks moving forward. Through this effort, we aim to ensure that data produced by our chapters IS of high quality.

What, Where, and Why Do We Validate?


Hub members access OSM data through Humanitarian OpenStreetMap Team’s (HOT) Tasking Manager, a tool that divides mapping projects into smaller tasks so multiple contributors can map and validate areas simultaneously. Projects in the HOT Tasking Manager indicate which areas are: ready to map, mapped, and validated. HOT’s system is designed to provide updated map data in the event of a disaster and/or humanitarian emergency scenario, measure project completion and user contributions, and improve the consistency of mapping (e.g. entities to map, proper feature tagging, etc.).


The YouthMappers Validation Hub executes the validation step in HOT’s Tasking Manager workflow. Hub members review the areas mapped by users, making sure that they trace and tag all map features required in the project instructions. When users do not follow the guidelines, our validators mark the area as ‘invalidated’, tag the user, and leave instructional friendly feedback in the comments section. The premise of this action is to encourage mappers to return to the task, fix their mapping oversights, and feel empowered to contribute to OSM in the future. 


When validating, our team look for three main things: 

  1. Spatial accuracy - are features in the correct place, are there overlapping buildings, are the corners of the buildings square, etc.?

  2. Tagging accuracy - are features tagged appropriately?

  3. Completeness - are all the features mapped as described in the HOT Tasking Manager project instructions?

Our validators pay close attention to these common mapping mistakes. To make sure YouthMappers edits adhere to OSM’s established guidelines on tracing and tagging, Hub members use a special software called Java OpenStreetMap (JOSM). 

Blog Post: Happy #ValidationFriday From the YouthMappers Validation Hub!

On October 25th, 2019, the Validation Hub hosted a validation party on The George Washington University’s campus. In honor of MissingMap’s #ValidationFriday, a reminder to validators to contribute to the data control and quality assurance of OSM data, the Hub gathered together to teach students and professionals on validation procedures using JOSM.

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Attendees of the Hub’s #ValidationFriday event posing with The George Washington University Geography alien mascot, Geoid. 

The Validation Process Using JOSM

Hub members prefer to validate using the advanced editing software JOSM. JOSM streamlines the geometry and tagging functions included in iD editor, coupled with built-in validation tools that automatically identify errors overlooked by the validator. However, these software tools alone are not the answer to validation. These tools need to be used by trained individuals who will assess the quality of the contributions made to OSM projects. Mappers that wish to become validators must have experience with tracing and tagging complex features in OSM, outstanding image interpretation skills, a positive attitude and manner towards other users, and a willingness to learn new software. 


If you possess an interest in learning to validate, please take a glance at our training document on validating using JOSM. JOSM is an open-source application that anyone can download and use without any cost. To download and read more about the software, click here. 


Validation Training Sessions


We believe that training with experienced validators, whether online or in-person, is essential to becoming a better mapper. Complementary to our instructional text and walk-throughs, we host validation training sessions to reinforce OSM’s code of conduct and work one-on-one with individuals to download, navigate, and validate using JOSM. This way, YouthMappers members with different levels of experience and interests can interact, learn from and help one another, and ask Hub members for assistance or questions.

Interactive / Active Validation Using HOT Tasking Manager and OpenStreetMap Changeset Analyser (OSMCha)


One of the goals of the Hub is to actively examine map edits, and correct errors and contact mappers if needed. This process, referred to as interactive/active validation, is applied to on-going projects. Our methodology is based on research which demonstrates that giving real-time feedback, both positive and corrective, yields higher quality edits and mappers. We perform interactive validation using either OSMCha or HOT Tasking Manager. 


OSMCha is an online tool with visual and analysis functions that support the standardization of OSM edits. As previously stated, HOT Tasking Manager is a tool that divides mapping projects into smaller tasks so multiple contributors can map and validate areas simultaneously. Whereas projects in HOT Tasking Manager pre-define the mapping region, OSMCha has the advantage of filtering options which enables individuals to refine changesets based on tags and attributes. The Hub has developed a walkthrough using OSMCha to review data by date range, location, and OSM username. You can follow our documentation here. 


Mapping Project Creation Form


Have an area that needs to be mapped? Let us help!

Typically, projects in HOT Tasking Manager focus on vulnerable regions

that lack spatial data. At-risk areas include communities prone to

natural disasters, armed conflict and displaced persons, insufficient food

and water supply, inequitable distribution of modern medicine, education,

and/or infrastructure, etc. If your idea is similar to the above examples,

you can submit a project proposal using our form here.

This questionnaire requires information such as the name and description

of the project, instructions on objects to map and specific tags,

bounding geometry for the area of interest, and other components

necessary for project creation. In addition, we provide

an instructional cheat sheet that gives written and visual examples

on how to map different kinds of features

(e.g. buildings, roads, waterways, etc.). 


What Tasks Have We Completed?


Our team has completed validating several YouthMappers-projects since May 2019. Our goal is to finalize tasks new and old to make certain that all data associated with YouthMappers is of excellent caliber and useful to the project creator and benefactors, and OSM users. Due to the size of projects, the complexity of map features and the quality of mapping by contributors, it takes varying amounts of time for our members to validate a project in the HOT Tasking Manager. Some tasks, such as #2742, required several months to complete due to its sheer scope. Others, like #990, necessitated less than a month because there were less features to map in the area. 


HOT Tasking Manager’s recent website redesign features a new graphic located on individual project pages labeled the ‘Contributions Timeline,’ which contrasts the amount of time to map tasks versus the amount of time to validate tasks. This graphic is supplementary to HOT Tasking Manager’s other maps and interactive displays, helping users to understand the completion rate of projects. 

Hub members overview the role and purpose of the Validation Hub. They also explain some of the resources created and available on this website page.

Contributions Webinar.png

This graphic belongs to HOT Project #2742: PEPFAR KENYA: SIAYA (BONDO), a task validated by the Hub. This project was completely mapped from April 2017 to January 2019, and validated between April 2019 to December 2019.


The Hub is made up of a group of experienced OSM student mappers and faculty from the George Washington University in Washington, D.C.

Kenneth Derryberry, Team Member: Kenneth joined the Validation Hub in June 2020. His hometown is Mountain View, California, and he is currently a rising junior at The George Washington University, pursuing a B.A. in Geography and Political Science with a minor in Geographic Information Systems. Kenneth’s humanitarian mapping experience began in his GIS courses, using OpenStreetMap to help catalog buildings in Bangladesh and Ethiopia. He is passionate about the importance of open source mapping and the ways that it can assist communities across the globe. Beyond his studies, Kenneth is actively involved in musical theater on campus.


Mei Harrison, Team Member: Mei joined the Hub in October 2021 as a senior at The George Washington University, who will graduate in the spring with a B.A. in Geography and International Affairs and a minor in Geographic Information Systems. Her passions for GIS and humanitarian mapping have flourished in various GIS courses where she has contributed to a number of projects. She hopes to take her open source software knowledge and GIS skills into a career where she can provide mapping services to help people of all backgrounds. Originally from Denver, Colorado, Mei loves to ski in the winter and hike around the DMV in her free time.


Maxwell Owusu, Team Member:  Maxwell joined the validation Hub in August 2021. Originally from Kumasi, Ghana. He is pursuing an M.S. in Geography and a Geographic Information Systems (GIS) Certificate at the George Washington University. He is a Graduate Research Assistant with a strong interest in the application of open source technology for geospatial analysis. Maxwell has been analysing OpenStreetMap contributions in humanitarian mapping. His research interest lies in poverty mapping, ethics, climate change and humanitarian management. Maxwell loves biking in his free time. 


Richard Hinton, Hub Manager:  Richard has been a part of YouthMappers since its inception and is a member of the steering committee as part of the George Washington University (GWU) team.  He is also the associated faculty for GWU’s YouthMappers chapter, the Humanitarian Mapping Society at GW (HMSGW). During his regular job at GWU, he manages the Department of Geography’s Spatial Analysis Lab, teaches GIS classes, and assists students, faculty and researchers with their geospatial projects.  Richard has been working in the geospatial industry for over twenty years and has long been interested in the application of open source technologies in humanitarian/disaster preparedness and response.  In working with HMSGW and YouthMappers he enjoys helping students realize the potential of OS technologies in this sector.


Blog Post: My Experience Joining the YouthMapper’s Validation Hub

Grace Donovan, a student at The George Washington University, writes about becoming a member of the Validation Hub in June 2019.


Validation Support

We strive to inform and encourage students at YouthMappers to advance their mapping techniques and image interpretation abilities by learning to validate using advanced editing tools. This guide includes detailed instructions, workflows, and other tips and tricks on validating in JOSM. Once you have a firm understanding and experience with validation you can use this Quick Reference Guide as a workflow reminder. 

​Hub members focus on ensuring YouthMappers projects have the highest quality data. We believe one way to achieve this goal is for mappers to use the JOSM editor. Considering this, we created a step-by-step document to download and set up JOSM and included keyboard shortcuts to easily use JOSM.

To improve mapping conduct, we engineered a methodology that enables us to give live feedback to OSM contributors. Using an online tool called OSMCha, our procedure utilizes the application’s filtering capabilities to review the behavior of mappers as they add map data. 

To streamline requests for tasks, we developed a project creation form where YouthMappers chapters can provide information needed to establish projects in HOT Tasking Manager. Our form requires information such as project description, location, instructions on mapping and tagging, and other necessary components.

Our tasking manager project creation instructions are intended for those who desire to create YouthMappers projects in HOT Tasking Manager. This document contains example project instructions, GIFs showing how to map features, and links to completed tasks that have excellent project descriptions and guidelines.

In order to make sure mappers generate data of the highest quality, our validators communicate with users in HOT to provide praise and corrective feedback on their work.  To help those interested in validating, we have prepared a document of validation messages, exemplifying the proper ways for validators to engage with mappers. This resource highlights key responses to small and large corrections and recommendations to interact kindly with users. With this, we provide room for mappers to understand and fix their errors, and promote confidence and comfort to keep contributing to OSM in the future.


Additional Validation Resources available on the YouthMappers Resource Library