OpenStreetMap

SHARCRASH

Mapper since: November 16, 2013

 

INTRODUCTION

Hello! I'm from Luxembourg and i map essentially natural and historical elements in nature such as former industrial zones, archaeological sites, folklore... My main motivations for mapping are exploration, mountain biking/hiking/trail running and share interesting places. See the last heading for my mapping and statistics details.

Feel free to contact me, i am opened to any discussion. If you have recommendations or corrections, please do not hesitate to tell me. Nevertheless, most often i check OSM's Wiki.

 

RECOMMENDATIONS FOR MAP CONTRIBUTORS

Beginners

● Reality can be materialized in OSM thanks to tags (key=value) which will identify what an element is embodying. There are 4 types of elements : - Nodes are points - Ways are lines with a direction sometimes meaningful. - Areas / Polygons are ways closed as a loop with direction sometimes meaningful. - Relations are a modular approach of several elements gathered into a structured data, these are setup differently. You create a relation, add its tags without forgetting the tag "type=value" and then link/add each element with its own respective tags to that relation. Examples: a tourist hiking route gathering several ways and its points of interest or small areas related inside bigger areas (MultiPolygons).

● Before any edit, make sure that your background tiles (satellite imagery, topogr., data, etc) are correctly aligned. For me as a reference, Geoportail.lu images (Luxembourg only) and worldwide Strava heatmap (on straight lines) are consistent and efficient for comparison. Beware of tilted sat. imagery even more on oblique surfaces (steep hills, mountains, etc), the exact position gets deformed depending on the angle between the satellite photos and those surfaces. How to check : search a close area with a building, the more you see the walls of the house, the more it's tilted but if you only see the roof, that's perfect. Select a less tilted image sat. source or realign the layer. Pros: any provider of satellite images should really be precise on this matter, it's not an option as so many people rely on these images without proper knowledge.

● Using one of the tags for the 1st time, check OSM's Wiki and respect what you want to incarnate! It has the consensus adopted by the OSM community and explains how to define elements. Trustful pages have a "status=adopted" or "status=de facto" (sometimes different btw languages) and see the taginfo statistics to see if it's widely used, over several thousands is a good start. Some are widely used but without status, like "natural=wood", others rarely used because of their specific kind. If you are not thorough, the data will be false, counterfeit the map and mislead other users and third party services which rely on OSM's data consensus to provide their services. Example... For an accident in nature, often team rescues use tracks with an all-terrain vehicle to reach the person, confusing paths and tracks is noxious. Imagine, if one day the map is used to rescue someone or even you.

● Precise position on elements is key for statistics whether it is for the ways and their route planning, on altitude via DEM/elevation contour or for calculating how much specific areas are being used in a region.

● 3rd party services which provide the planning of route directions add already the highway's default access properties. No need to add obsolete access properties which may mislead via the map tiles. Example: adding tag access=no (general access with any means of mobility) and foot=yes on a highway=footway is unnecessary since by default this type of highway is an element only for pedestrians, this tag combination will grey out the way as inaccessible on the rendered map tiles and mislead users who will think it's not accessible at all.

● Access=no, is mostly used when the element exists but isn't anymore accessible by its default means of mobility and for anyone. Example: think of a building in ruins or a way having collapsed rocks. Access=private is accessible though only for the owners and eligible users. Access=permissive is not officially a public element but the owner allows access until further notice.

● Editor apps... If you are experienced and make many complex edits, use JOSM. If you are beginner and make small new contributions of areas or ways, use iD. Creating big/many areas and ways or editing them in iD is tedious though, i heavily recommend JOSM along plugins such as "Improve way accuracy" & "Merge contour" instead (more info in the plugin's page). Potlatch is outdated, do not use it.

 

RANTS (UNFORTUNATLY)

● People not using tags (key=value) properly according reality and what has been approved as standard in OSM's wiki. See "Recommendations" above why.

● Too many people contributing without precision up to a point you must wonder if some areas are worth trusting, even with simple polygons. My guess is that they don't want to disconnect/reconnect all the nodes which in iD and Potlach is very tedious.

● Automations (JOSM plugins) and other importations without post processing. We get : area intersections, awkward plotting (UE SOeS CORINE Land Cover is totally useless), large areas having a huge offset, buildings having multiple tiny polygons whereas it's a single building, this adds loads of futile data...

● People who do not check back the results of their contributions, introducing errors, OSMinspector is (was) your friend.

● Intolerant people not faithful to the open source philosophy, trying to forbid other users to use features extensively ALLOWED in OSM, forcing them also to use another workflow which may not meet their expectations. It's unfair, dictatorial and discriminatory! I've experienced this problem with the OSMF forcing me to stop creating MP elements (had blocked me), these being discriminated in favor of simple areas because they were too complicated for some simple minded people... You are reading well! The iD editor is OK for creating new elements but it's HELL to update interconnected elements. Reminder in this link , read the 1st paragraph. If you feel the same way, you're welcome to contact me.

 

MAPNIK LAYER BUGS

● 8 shaped MP, in other words several areas part of the same MP but touching themselves only at 1 node (hence the "8 shape" name i gave) some of the areas will sometimes not render, depending of some factors (size, tagging...?)

● area and line elements inside highway areas will not render, normal for highway lines but barriers etc should definitely be rendered, you can still make sure to render areas such as buildings by making the highway area as MP and adding an inner relation. My guess for this bug is that these highway areas follow the code structure of the highway lines, so they have also the highest priority of rendering over all other elements.

 

PERSONAL MAPPING & STATISTICS

Areas on map

Global statistics

All users Luxembourg statistics, usually I'm n°1

 

Areas that I mapped extensively with other users :

● Terres Rouges (Redlands) ins South of Lu (Lu / Fr side)

● Grengewald (Lu)

● Petite Suisse (Lu)

● Mamerdaal (Lu)

● Forêt d'Anlier (Be)

 

Areas that i mapped nearly alone :

● Micheville former industrial zone (Fr)

● Bois de Butte (Fr)

 

Areas that i plan developing/detailing :

● Bois de Gaume, Forêt d'Anlier (Be) & other Southern Forests/Woods

● North of Luxembourg

● North of Trier (De, meantime contributors have already done a lot work)

Cheers! :)