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Canaan OSM Tracing Guide

#OSM Tracing Guide for Canaan, Haiti

In 2010, a magnitude 7 earthquake struck Port-au-Prince, Haiti, destroying hundreds of thousands of buildings and displacing 2.3 million people. 50,000 of these individuals resettled in Canaan, on the northern outskirts of Port-au-Prince. Canaan has not been formally recognized by the government and lacks running water, electricity, paved roads, and other services. We're mapping the area as part of a risk reduction and urban planning effort.

This tracing guide focuses on the most important features in the area: roads, buildings, and walls.

##Getting started

First, make sure you're using the right background imagery. iD Editor will default to using Bing aerial, but for this area we have high-res drone imagery.

You can change the imagery like so:


First we trace them, then we classify them. The whole process looks like this:

###Tracing roads

To trace a road, use the Line tool in iD Editor (Shortcut: 2) and trace along the middle of the road. See below for an example of too few nodes (left), too many nodes (center), and the right amount of nodes (right).

Make sure the roads connect to each other where they cross. You should see a node appear at each intersection (see below).

###Classifying roads

The roads in Canaan are all unpaved, but we want to distinguish between them. We will use three classifications: tertiary road, residential road, and track.

  • Residential. The majority of roads that you see in the drone imagery should be classified as "residential". These roads are easily seen in the drone imagery but won't look particularly wide - most of them are only about one lane wide. When in doubt, classify a road as residential.
  • Tertiary. The most obvious, widest paths that you see should be classified as "tertiary roads". These roads are easily seen in the drone imagery and will seem wide enough for two cars to pass.
  • Tracks. The remaining paths that you see should be classified as "tracks". Tracks are trails and paths that only a 4WD vehicle, a motorbike, or a pedestrian would be able to travel. They will be faint and difficult to see, they might appear and then disappear, and they may look like footpaths between houses or within a single piece of property.

The images below should give a general sense of what these features look like. Note that many of the existing roads in St. Christophe are classified as tracks but should actually be residential roads - keep an eye out if you are mapping this area.

Once you've classified the type of road, next set the surface to "ground". The gif above shows how to do this.

##Buildings and walls

###Understanding what's what.

There's a lot of construction going on in Canaan, especially on the east side in Onaville. We're interested in the following types of area:

  • Buildings. These will look like "normal" structures, with roofs, walls, etc. They may be constructed from primitive materials.
  • Buildings under construction. These will look like walls, but about the size of a building and with partitions for rooms. These could be dark (indicating that a foundation has been dug), lighter (indicating a filled-in foundation, maybe with short walls), or white with shadows (the walls are getting taller)
  • Property walls. The walls will be obvious because they cover a larger area than buildings under construction.

Here's what these areas will look like on the drone imagery:

###Tracing buildings and walls

To trace, select the Area tool (Shortcut: 3) and draw around the building/wall. If you don't see the "Building under construction" type, try searching for it in the search box. The process looks like this:

Note that once you've traced a building, you can square the corners easily by hovering and clicking the icon (Shortcut: s)

That's it! For more resources, see:

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