# Stairs Modeling Proposal
**Author: Jan Schmalfuß-Schwarz**

## Aim of the Proposal for Stairs in Buildings
This proposal aims to define a standardized tagging schema for mapping stairs in buildings according to the Simple Indoor Tagging (SIT) Schema. This includes capturing not only the geometric shape of the stairs but also their pathway, enabling precise indoor navigation, 3D modeling, and providing necessary accessibility information.

## Description of the Tag
Stairs in buildings are already described using the tagging schema indoor=room or indoor=area and stairs=yes. This proposal supplements these tags with the pathway of the stairs, defined by a start- and end-node along the outline of the stairs and several nodes within the object.

## Example of a U-Shape

// example nodes pathway
<node id=”6”>
    <tag k=”level” v=”0” />
    <tag k=”point:lowest” v=”yes” />
</node>

<node id=”5”>
    <tag k=”level” v=”1” />
    <tag k=”point:highest” v=”yes” />
</node>

<node id=”7”>
    <tag k=”level” v=”0.5” />
</node>

<node id=”8”>
    <tag k=”level” v=”0.5” />
</node>

<node id=”9”>
    <tag k=”level” v=”0.5” />
</node>

<node id=”10”>
    <tag k=”level” v=”0.5” />
</node>

// example stair shape
<way id=”1”>
    <nd ref=”1” />
    <nd ref=”2” />
    <nd ref=”3” />
    <nd ref=”4” />
    <nd ref=”5” />
    <nd ref=”6” />
    <tag k="level" v="0-3" />
    <tag k=“indoor“ v=“room“ />
    <tag k=”stairs” v=”yes” />
</way>

// example stair pathway
<way id=”2”>
    <nd ref=”6” />
    <nd ref=”7” />
    <nd ref=”8” />
    <nd ref=”9” />
    <nd ref=”10” />
    <nd ref=”5” />

    <tag k=“indoor“ v=“pathway“ />
    <tag k=”level” v=”0-1” />
    <tag k=”repeat_on” v=”1;2” />
    
    // Notes: 
    // tag as steps
    // low and high point is redundant
    // extend of the steps (dimension)
    // level in stair shape
    // on which points can you leave the stair?
    // don't map with repeat_on
    // count of steps
</way>

## Use of Accessibility Tags
In addition to the above-mentioned tags, well-known accessibility tags such as handrail=*, tactile_paving=* and platform_lift=* can be used to provide information about the accessibility of the stairs.

## Impacts and Compatibility
The addition of this tag has minimal to no impact on existing applications, as indoor mapping is not yet widely adopted. However, it adds value by improving indoor navigation and mapping.

## Discussion and Feedback
Feedback and discussions regarding this proposal are welcome and can be conducted on the appropriate discussion page in the OpenStreetMap Wiki.