Relaskop Critical Distance

Compare slope-corrected horizontal tree distances to angle-count critical radii with a caller borderline tolerance; codes +1/0/-1 mean included/ambiguous/excluded and do not automatically assign border-tree weights.

Description

Angle-count inclusion depends on tree diameter and horizontal distance from the sampling point.

Angle-count inclusion depends on tree diameter and horizontal distance from the sampling point. Slope measurements need projection before comparison with critical distance.^[1]

When to use Relaskop Critical Distance

Use this tool to compare slope-corrected horizontal tree distances to angle-count critical radii with a caller borderline tolerance; codes +1/0/-1 mean included/ambiguous/excluded and do not automatically assign border-tree weights.

Gather the tree inventory, plot measurements or model parameters. Check diameter, area, time and moisture conventions; keep paired observations aligned.

How to use Relaskop Critical Distance and understand its results

Gather the tree inventory, plot measurements or model parameters. Check diameter, area, time and moisture conventions; keep paired observations aligned.
Enter treeDbhsCm, slopeDistancesM, slopeAnglesDegrees, basalAreaFactorM2PerHectare, distanceMeasurementToleranceM using the field table and calculation rules, then run the tool.
Read criticalHorizontalDistancesM, observedHorizontalDistancesM, inclusionCodes. The explanation below defines the units, signs, ordering and any flags or placeholder values.
If the tool reports an input issue, correct the values and run it again. Apply the stated assumptions when interpreting a successfully returned result.

Input field	Meaning	Value type; see rules below	Requirement
treeDbhsCm	Tree dbhs cm	list of number	Required
slopeDistancesM	Slope distances m	list of number	Required
slopeAnglesDegrees	Slope angles degrees	list of number	Required
basalAreaFactorM2PerHectare	Basal area factor m2 per hectare	number	Required
distanceMeasurementToleranceM	Distance measurement tolerance m	number	Required

Pair positive DBH, nonnegative slope distance and angles strictly between −90° and 90°; supply positive metric BAF and nonnegative distance tolerance. Return distances and codes +1 included, 0 ambiguous within tolerance, −1 excluded.

Paired lists must be nonempty and have equal lengths.

critical m=DBH cm/(2sqrt(BAF)); horizontal distance=slope distance × cos(slope)

Units, indexing, boundary conditions and exceptional cases are defined in the calculation rules above.

Output field	Meaning	Value type
criticalHorizontalDistancesM	Critical horizontal distances m	list of number
observedHorizontalDistancesM	Observed horizontal distances m	list of number
inclusionCodes	Inclusion codes	list of number

json

{
  "input": {
    "treeDbhsCm": [
      20,
      20,
      20
    ],
    "slopeDistancesM": [
      5,
      10,
      15
    ],
    "slopeAnglesDegrees": [
      0,
      0,
      0
    ],
    "basalAreaFactorM2PerHectare": 1,
    "distanceMeasurementToleranceM": 0.1
  },
  "output": {
    "criticalHorizontalDistancesM": [
      10,
      10,
      10
    ],
    "observedHorizontalDistancesM": [
      5,
      10,
      15
    ],
    "inclusionCodes": [
      1,
      0,
      -1
    ]
  }
}

Limitations and assumptions

Borderline codes do not assign half-tree weights automatically. Sampling protocol and measurement uncertainty remain caller responsibilities.

Numeric inputs and returned numeric values must be finite; an unrepresentable returned value produces an error. Numeric lists are limited to 100,000 entries; the rules above may require smaller limits. Missing required fields, extra fields, wrong value types and violations of the calculation rules are input errors.

Alternative or Complementary methods

Use Prism Basal Area Factor: Convert measured prism deflection angle to metric BAF and sum caller inclusion weights, including explicitly half-counted border trees; sampling protocol determines weights and this is not a fixed-plot tree-area alias. For a complementary task, use Species Importance Value: Calculate the three-component 0–300 importance-value convention from measured stems, basal area and plot occurrences; not percentage dominance alone or ecological importance certification.

References

Relaskop Critical Distance — tool.io

Similar or alternative tools

Prism Basal Area Factor
Convert measured prism deflection angle to metric BAF and sum caller inclusion weights, including explicitly half-counted border trees; sampling protocol determines weights and this is not a fixed-plot tree-area alias.
Species Importance Value
Calculate the three-component 0–300 importance-value convention from measured stems, basal area and plot occurrences; not percentage dominance alone or ecological importance certification.