User:Ianlopez1115/Dealing with various errors

The following is an essay on tackling data-related problems and challenges faced by the OpenStreetMap Philippines community.

Introduction

Five years ago, the Philippines was mostly a blank space in OpenStreetMap. After five years, over a thousand contributors, over two million nodes and almost eighty-five thousand kilometers of highways, we are arguably one of the most active countries in this part of the world.

Because of our efforts in adding, modifying and updating OpenStreetMap data, more people are using it for navigation purposes. However, some edits are less helpful than others, and this essay tries to find out the errors, problems and challenges and provide solutions.

Errors, Problems and Challenges in a nutshell

See also Errors.

Picture	Category	Implications
	Unconnected highways (touching)	This is a severe error when looking at routing applications. Connected roads are not connected in OSM data.
	Unconnected highway (open)	This may be a severe error when looking at routing applications.
	Crossing on same layer without common node	Either bridge or tunnel and layer is missing or a common node is missing. Either reality is not reflected correctly or routing cannot be done correctly because roads are not connected in data.
	Open areas	Reality is not reflected correctly, some programs might have problems using those polygons.
	Oneway errors on dual carriageways	Routing cannot be done correctly, may cause vehicular accidents
	Self-intersecting ways	Routing cannot be done correctly
	Roundabouts with wrong direction	Routing cannot be done correctly
	Tagging for the renderer	Map looks "horrendous", routing cannot be done correctly in some cases
	Changesets without comments	You're not giving other mappers a hint of your maping activity

Errors, Problems and Challenges in detail

Intersecting ways without a connecting node

This particular error is often repeated by new contributors. It can be fixed through Potlatch2 by pressing the shift button while simultaneously clicking the intersecting ways.

Self-intersecting ways

This particular error is often repeated by new contributors. So, how do we fix it?

Since many new OSM contributors use Potlatch2, it is appropriate for the user to fix it using the said application. (If you know how to fix self-intersecting ways in JOSM, go here.) But first, we have to find spots that have such errors. Fortunately, we have OSM Inspector.

After spotting a bunch of self-intersection points (visualized in OSM Inspector as a little red X-mark), click on that mark. A selection will be shown at the right side of the page. Click on the "P" icon. It will direct you to the Editing tab. For a better view of this illustration, point your mouse towards the picture on your right.

At this point, the way with self-intersecting points will be modified. A demonstration on how to fix self-intersecting ways can be viewed at http://www.youtube.com/watch?v=5rnBHhD3HUs .

Roundabouts/traffic circles with wrong direction

This error affects routing. The Philippines is a right hand country. Thus, the traffic flow of roundabouts and traffic circles in this country is anti-clockwise (see the animated image on the right)

Tagging for the renderer

This error negatively affects the following:

• Routing/navigation services
• The various map renderers

Some errors that fall under this category are:

• Mistagging of various elements (examples below)
  • Government offices tagged as tourism=museum
  • Farm areas (usually rice fields) tagged as meadows
  • Towns tagged as name=[name of place] Barangay/Town/Municipal/City Hall, place=village/town/city
  • Drainage ditches tagged as canals
  • Tagging school buildings as amenity=public_building or amenity=school without the proper building tag
  • Double spacing in names
• Improper Capitalization
  • Using all caps (Example: name=RIZAL STREET for Rizal Street)

Edits that partially or do not reflect reality

This error affects routing services and may cause untoward incidents. Some examples of it are Unconnected ways and barriers not connected to a highway way.

Changesets without comments

This error negatively affects the following:

• Other mappers who want to know how their fellow mappers are doing (adding places of interest, removing edits from a tainted source, etc.)

This can be fixed by adding meaningful comments. However, adding things like "editing (name of place here)" may further confuse other mappers - it is best to be a bit more specific (Example: "Added new roads and places of interest in (name of place)")

Other things

• Take note of other users' good practices
  • Some examples of good practices are following the One feature, one OSM element principle, adding insightful and helpful comments to changesets and not removing tags and features that you don't understand
• To maximize the use of Potlatch2, use the "Enhanced" map style.

TODO

Add/improve explanation
Add pics to illustrate
Change to a less contentious title (if needed)