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Layer TypeDescriptionExample
Point- single location in space
{
  "type": "Feature",
  "geometry": {
    "type": "Point",
    "coordinates": [
      77.038,
      28.728
    ]
  },
  "properties": {}
}

Introduction

1. Layers in GIS​

A layer in GIS is a visual representation of geographic data. Think of it as a transparent sheet that contains specific types of information, such as roads, buildings, or rivers. Layers can be stacked on top of each other to create a map. For example:

  • A point layer could represent locations like schools or hospitals.
  • A line layer could represent roads or rivers.
  • A polygon layer could represent areas like parks or buildings.

GeoJSON Layer Types​

vector raster types

Example: Point Layer​

{
  "type": "Feature",
  "properties": {},
  "geometry": {
    "coordinates": [77.03829503966722, 28.72860558842251],
    "type": "Point"
  }
}

Example: Polygon Layer​

{
  "type": "Feature",
  "properties": {},
  "geometry": {
    "coordinates": [
      [
        [77.05173906504365, 28.615648951380365],
        [77.0364072321629, 28.615648951380365],
        [77.0364072321629, 28.595601480628332],
        [77.05173906504365, 28.595601480628332],
        [77.05173906504365, 28.615648951380365]
      ]
    ],
    "type": "Polygon"
  },
  "id": 1
}

2. Feature Layers​

A feature layer is a collection of geographic features (points, lines, or polygons) that share the same geometry type and attributes. Each feature in a feature layer has:

  • Geometry: The shape (point, line, or polygon).
  • Attributes: Descriptive information (e.g., name, population, etc.).

In your example:

  • The point feature represents a single location (e.g., a landmark or address).
  • The polygon features represent areas (e.g., a park or building).

3. Geometric Feature Layers​

A geometric feature layer refers to a feature layer where the geometry (shape) is the primary focus. For example:

  • A point layer could represent trees in a park.
  • A line layer could represent hiking trails.
  • A polygon layer could represent the boundaries of the park.

In your example:

  • The point feature is a geometric feature layer with a single point.
  • The polygon features are geometric feature layers representing areas.

4. Dimensions in GIS​

Dimensions refer to the spatial characteristics of features:

  • 0D (Zero-Dimensional): Points (e.g., a location).
  • 1D (One-Dimensional): Lines (e.g., roads or rivers).
  • 2D (Two-Dimensional): Polygons (e.g., buildings or parks).
  • 3D (Three-Dimensional): Volumes (e.g., buildings with height).

In your example:

  • The point feature is 0D.
  • The polygon features are 2D.

5. Example Breakdown of Your Geolocation Data​

Feature 1: Point​

{
  "type": "Feature",
  "properties": {},
  "geometry": {
    "coordinates": [77.03829503966722, 28.72860558842251],
    "type": "Point"
  }
}

Type: Point (0D). Coordinates: A single location (latitude: 28.7286, longitude: 77.0383). Example: This could represent a landmark, like a statue or a building.

Feature 2: Polygon​

{
  "type": "Feature",
  "properties": {},
  "geometry": {
    "coordinates": [
      [
        [77.05173906504365, 28.615648951380365],
        [77.0364072321629, 28.615648951380365],
        [77.0364072321629, 28.595601480628332],
        [77.05173906504365, 28.595601480628332],
        [77.05173906504365, 28.615648951380365]
      ]
    ],
    "type": "Polygon"
  },
  "id": 1
}

Type: Polygon (2D). Coordinates: A closed shape with five vertices (a rectangle). Example: This could represent a park or a building footprint.

Feature 3: Polygon​

{
  "type": "Feature",
  "properties": {},
  "geometry": {
    "coordinates": [
      [
        [77.0485430445732, 28.591178572542205],
        [77.0485430445732, 28.584015637132552],
        [77.05473143947859, 28.584015637132552],
        [77.05473143947859, 28.591178572542205],
        [77.0485430445732, 28.591178572542205]
      ]
    ],
    "type": "Polygon"
  }
}

Type: Polygon (2D). Coordinates: Another closed shape with five vertices. Example: This could represent a smaller area, like a playground or a parking lot.

  • Attributes: Properties associated with features (e.g., name, population, area). In your example, the properties field is empty, but it could include details like "name": "Central Park".
  • Spatial Reference: The coordinate system used (e.g., WGS84 for latitude/longitude).
  • Overlay Analysis: Combining layers to analyze relationships (e.g., finding points within a polygon).
  • Symbology: How features are styled (e.g., color, size, or shape).

Visualization Example​

If you were to visualize your FeatureCollection:

  • The point would appear as a single dot on the map.
  • The polygons would appear as shaded areas (e.g., rectangles).