Passage Cross Section Area Estimator

Shoelacearea of actual ordered simple independently surveyed passage boundary, no holes. Reject self-intersections; not assume width×height for irregular cave geometry.

Description

An ordered surveyed passage boundary can define a simple polygonal cross-section.

An ordered surveyed passage boundary can define a simple polygonal cross-section.^[1]

Holes, overlapping edges and unsampled geometry require a different representation.

When to use Passage Cross Section Area Estimator

Use this tool to obtain observedPolygonalPassageAreaSquareMeters from the supplied records using the stated calculation. Establish the survey or observation scope, reference frame, units and independently applicable calibration or qualified plan.

How to use Passage Cross Section Area Estimator and understand its results

Establish the survey or observation scope, reference frame, units and independently applicable calibration or qualified plan.
Enter actualOrderedPassageBoundaryXyMeters, using the field meanings and rules below, then run the tool.
Read result.observedPolygonalPassageAreaSquareMeters. Use the units and sign conventions below, and review any unknown records separately.
Correct any reported input issue and run again. Before using a successful result, check the stated units, signs, reference scope and observation coverage.

Input field	Meaning	Value type	Requirement
actualOrderedPassageBoundaryXyMeters	Actual ordered passage boundary xy meters	numeric matrix	Required

Supply three through 128 distinct ordered finite xy vertices in metres, each row exactly two values. Closure is implicit: do not repeat the first vertex. Reject intersections or contacts between nonadjacent edges, including collinear overlaps. Compute the absolute shoelace area and require it positive. Clockwise and counterclockwise simple boundaries are accepted; holes are not represented.

areaM2=abs(Σ(x_i×y_(i+1)−y_i×x_(i+1)))/2, wrapping final vertex to first

Use the matching field units and the exact boundary, ordering and reference rules above.

Output field	Meaning	Value type
result	Qualified observed calculation or explicit reference	object
result.observedPolygonalPassageAreaSquareMeters	Observed Polygonal Passage Area Square Meters	number

json

{
  "input": {
    "actualOrderedPassageBoundaryXyMeters": [
      [
        0,
        0
      ],
      [
        2,
        0
      ],
      [
        2,
        3
      ],
      [
        0,
        3
      ]
    ]
  },
  "output": {
    "result": {
      "observedPolygonalPassageAreaSquareMeters": 6
    }
  }
}

Limitations and assumptions

The actual observation coverage, calibration and qualified plan determine applicability. A numerical result does not establish survey accuracy, route suitability, atmosphere conditions or equipment adequacy beyond the declared comparison.

Missing required fields, unknown fields, wrong types and violated rules return input issues. Numeric values and outputs must be finite. Lists and matrices must be dense, without missing cells. Numeric matrices allow at most 128 rows and 128 columns, subject to the narrower shape requirements above. Extremely large composite outputs are rejected.

Alternative or Complementary methods

For a related step, use Passage Width-to-Height Aspect Classifier: Passage aspect compares measured width with measured height. For a complementary comparison, use Canyon vs Tube Passage Shape Classifier: Canyon and tube morphology can be represented by independently assessed feature annotations.

References

Passage Cross Section Area Estimator — tool.io

Similar or alternative tools

Passage Width-to-Height Aspect Classifier
Passage aspect compares measured width with measured height.
Canyon vs Tube Passage Shape Classifier
Canyon and tube morphology can be represented by independently assessed feature annotations.