Field-of-view NPM

field-of-view

field-of-view is a JavaScript library to create photo fields of view GeoJSON geometries. field-of-view can be used in tools for photo geotagging, for example:

Leaflet.GeotagPhoto - Leaflet plugin for photo geotagging
Surveyor - web application for crowdsourced image geotagging
Street View, Then & Now: New York City's Fifth Avenue

field-of-view is developed for The New York Public Library's NYC Space/Time Directory.

Input

Point: camera location
LineString with two points: field of view
GeometryCollection with two Point geometries: camera and target locations
GeometryCollection with three Point geometries: camera and target locations, and a point to determine the angle of the field-of-view

See the API section for more details.

Output

GeometryCollection with two geometries:
1. Point: location of camera
2. LineString: field of view

Example:

{
  "type": "Feature",
  "properties": {
    "angle": 45,
    "bearing": -87.81893783,
    "distance": 690.3534921
  },
  "geometry": {
    "type": "GeometryCollection",
    "geometries": [
      {
        "type": "Point",
        "coordinates": [
          4.918044805,
          52.379463370
        ]
      },
      {
        "type": "LineString",
        "coordinates": [
          [
            4.908044296,
            52.38226812
          ],
          [
            4.90772491,
            52.37713015
          ]
        ]
      }
    ]
  }
}

npm.io

Installation

Using Node.js:

npm install field-of-view

Browser:

<script src="https://unpkg.com/field-of-view"></script>

Usage

Node.js example:

const fieldOfView = require('field-of-view')

const feature = {
  type: 'Feature',
  properties: {
    angle: 50
  },
  geometry: {
    type: 'LineString',
    coordinates: [
      [
        4.90028,
        52.37249
      ],
      [
        4.90065,
        52.37262
      ]
    ]
  }
}

const fov = fieldOfView.fromFeature(feature)

console.log(fov, null, 2)

API

`fieldOfView.fromFeature (feature, options)`

Converts feature to Field of View geometry; feature must be one of the following GeoJSON objects:

Point
- Point is camera location
- properties.bearing should be specified
- properties.distance should be specified
LineString with two points; this is the field of view of the photo
GeometryCollection with two Point geometries
1. Point location of the camera
2. Point location of the camera's target
GeometryCollection with three Point geometries
1. Point location of the camera
2. Point location of the camera's target
3. Point determining the angle of the field-of-view

In all cases except the last, features must specify the camera's angle of view by setting properties.angle, or by passing the angle as an option to the field-of-view module:

const options = {
  angle: 45
}

fieldOfView.fromFeature returns a single feature with a GeometryCollection containing two geometries, the location of the camera and the field of view. The feature's properties contains three values:

angle: angle of view of camera (0 - 180)
bearing: bearing of camera (0 - 360)
distance: distance between camera and target, in meters

See the Output section for an example.

field-of-view v0.2.2