We know OpenStreetMap is one of the most powerful and collaborative geospatial databases in the world. It relies on contributions from everyday users, developers, humanitarian workers, and mapping enthusiasts to keep data accurate and up to date.
But like any open data project, OSM faces issues. And understanding the types of issues we encounter is essential to maintaining map quality. One simple and effective way to think about OSM data problems is, to divide them into two broad categories:

1. Existing Issues: Errors in the Map

These are problems that exist within the current OSM data. The features are already mapped, but something about them is incorrect, inconsistent, or outdated.

Common examples:

• Incorrect tags: A residential road tagged as a motorway.
• Geometry errors: Buildings that are misaligned, roads that don’t connect properly, or rivers overlapping with buildings.
• Outdated features: A shop that closed years ago but still shows up on the map.
• Inconsistencies: Using different tags for the same type of feature in nearby areas (amenity=school vs. building=school).

2. Non-Existing Issues: Missing from the Map

These are features or data that should be on the map but are completely absent. The problem here is not about fixing what’s wrong, it’s about recognizing what’s not there at all.

Common examples:

• Unmapped buildings visible in satellite imagery.
• New roads or paths that haven’t been digitized.
• Missing POIs like schools, hospitals, or shops.
• Lack of metadata such as opening hours, accessibility info, or addresses.

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Why This Distinction Matters

Thinking in terms of “existing” vs. “non-existing” issues helps:

• Prioritize tasks: Fixing vs. adding require different skills and time.
• Guide new mappers: Beginners can focus on adding missing data, while experienced users fix complex issues.
• Organize mapping campaigns: Humanitarian or local efforts can be tailored to the type of issue in a region.
• Improve data validation: Tools like OSMCha, or Osmose focus on identifying existing issues, while others like MapSwipe or HOT Tasking Manager target missing data.

Please comment your thoughts and write another diary by linking this problem sets with your solutions.