Wing Landmark Scale Gap Tool

Description

pixelDistance is their Euclidean separation; inferredLength = pixelDistance/suppliedPixelsPerLength; lengthGap = inferredLength-referenceLength.

Insect morphology measurements depend on landmark definitions, image scale and specimen condition. A length ratio can be dimensionless while a calibrated coordinate has physical units; neither arithmetic operation validates anatomical correspondence or preservation assumptions.

pixelDistance is their Euclidean separation; inferredLength = pixelDistance/suppliedPixelsPerLength; lengthGap = inferredLength-referenceLength.

When to use this tool

Use Wing Landmark Scale Gap when checking a supplied morphological measurement, calibration or length ratio.

How to use the tool and how it works

Enter firstLandmark, secondLandmark, suppliedPixelsPerLength, referenceLength. Keep parallel arrays aligned. Use the units and conventions below.
Run the tool. Correct any format, range, or cross-field input error before interpreting the output.
Read pixelDistance, inferredLength, lengthGap. Use the output convention below.

Require two coordinates in each landmark, nonnegative referenceLength and positive suppliedPixelsPerLength. pixelDistance is their Euclidean separation; inferredLength = pixelDistance/suppliedPixelsPerLength; lengthGap = inferredLength-referenceLength.^[1]

Input field	Meaning and units	Accepted input
firstLandmark	First Landmark	Required. Array of finite number; maximum items 256.
secondLandmark	Second Landmark	Required. Array of finite number; maximum items 256.
suppliedPixelsPerLength	Supplied Pixels Per Length	Required. Finite number; strictly above 0.
referenceLength	Reference Length	Required. Finite number; minimum 0.

Output field	Interpretation	Returned shape
pixelDistance	Pixel Distance	Required. Finite number.
inferredLength	Inferred Length	Required. Finite number.
lengthGap	Length Gap	Required. Finite number.

json

{
  "input": {
    "firstLandmark": [
      0,
      0
    ],
    "secondLandmark": [
      3,
      4
    ],
    "suppliedPixelsPerLength": 2,
    "referenceLength": 2
  },
  "output": {
    "pixelDistance": 5,
    "inferredLength": 2.5,
    "lengthGap": 0.5
  }
}

Limitations and assumptions

Calibration is pixels per physical length, not its inverse. The tool does not detect landmarks, verify the scale or correct projection and preservation effects.
Inputs must satisfy both the field types and the cross-field conditions above. Invalid input causes an error; a successful false flag or documented placeholder is a different result.
Numeric calculations use binary floating point unless exact decimal-integer arithmetic is explicitly stated. No hidden measurement tolerance or decimal rounding is added; nonfinite or out-of-contract results are rejected. Numeric signed-zero results are exported as zero.

Alternative or Complementary methods

Use verified imaging calibration and appropriate specimen methods for anatomical interpretation, and propagate uncertainty when measurement precision matters.

References

Calculation and input contract: entomology/wing-landmark-scale-gap — tool.io

Similar or alternative tools

Wing Venation Landmark Coordinate Scale
relativeX = (x-referenceX)*scale; relativeY = (y-referenceY)*scale; distance = hypot(x-referenceX,y-referenceY)*scale.
Insect Body Length Scale Factor
lengthPerPixel = suppliedRulerLength/rulerPixels; physicalLength = bodyPixels*lengthPerPixel.