GPS Fuzzing Example - IBUNAM Computer Lab

gps_fuzz_ibunam.geojson

{
  "type": "FeatureCollection",
  "features": [
    {
      "type": "Feature",
      "geometry": {
        "type": "Point",
        "coordinates": [
          -99.194494,
          19.320514
        ]
      },
      "properties": {
        "name": "Exact location of IBUNAM computer lab (19.320514, -99.194494)",
        "address": "Coyoacán, 04510 Ciudad de México, D.F., Mexico"
      }
    },
    {
      "type": "Feature",
      "geometry": {
        "type": "Point",
        "coordinates": [
          -99,
          19
        ]
      },
      "properties": {
        "name": "Fuzzed GPS coordinates, rounded to nearest whole number: (19, -99)"
      }
    },
    {
      "type": "Feature",
      "geometry": {
        "type": "Point",
        "coordinates": [
          -99.2,
          19.3
        ]
      },
      "properties": {
        "name": "Fuzzed GPS coordinates, rounded to nearest 10th of a degree: (19.3, -99.2)"
      }
    },    
    {
      "type": "Feature",
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [
              -99.5,
              19.5
            ],
            [
              -98.5,
              19.5
            ],
            [
              -98.5,
              18.5
            ],
            [
              -99.5,
              18.5
            ],
            [
              -99.5,
              19.5
            ]
          ]
        ]
      },
      "properties": {
        "name": "Fuzzed Rectangle from rounding to closest whole number"
      }
    },
    {
      "type": "Feature",
      "geometry": {
        "type": "Polygon",
        "coordinates": [
          [
            [
              -99.25,
              19.35
            ],
            [
              -99.15,
              19.35
            ],
            [
              -99.15,
              19.25
            ],
            [
              -99.25,
              19.25
            ],
            [
              -99.25,
              19.35
            ]
          ]
        ]
      },
      "properties": {
        "name": "Fuzzed Rectangle from rounding to closest 10th of a degree"
      }
    }    
  ]
}

The real "decimalLatitude" and "decimalLongitude" values of this record are 19.320514 and -99.194494, but we want to "fuzz" the coordinates to protect it. To do that, we'll use the "coordinatePrecision" field.

If we choose a "coordinatePrecision" value of "1.0 (nearest degree)", "decimalLatitude" and "decimalLongitude" become 19 and -99. This means that the specimen's coordinates have been rounded to the closest whole degree, and it could have come from anywhere in the largest rectangle.

If we choose a "coordinatePrecision" value of "0.1 (nearest 10th of a degree)", "decimalLatitude" and "decimalLongitude" become 19.3 and -99.2. This means that the specimen's coordinates have been rounded to the closest whole 10th of a degree, and it could have come from anywhere in the smaller rectangle.