Random Terrain Profile Generator

Description

Generate uniform-x integer height controls, flat or cardinal finite-difference Hermite tangents, a bounded sampled decorative profile, polyline length, and normalized SVG; inherited Hermite rounding is 12 significant digits on normalized heights, not physical terrain or an exact arc length.

Procedural artwork expresses a visual idea through coordinates, repeated motifs, colors, or explicit placement constraints. A coordinate plan can be checked and reproduced before rendering, while physical material behavior and fabrication require separate information.

When to use this tool

Use this generator to create reproducible terrain profile cases from the supplied model or bank. Inspect the returned evidence before using cases in a test or exercise.

How to use the tool and how it works

Supply controlCount, width, minimumHeight, maximumHeight, tangentMode, subdivisions in the field shapes below. Set seed when you need an explicit replay.
Run the tool and correct any input error. For generated controls, distinguish a successful fixture containing an invalid case from failure to generate the fixture.
Read controls, samples, sampledPathLength, svg. Use the conventions below and keep answer-bearing fields separate when presenting an exercise.

Place controls at uniformly spaced x positions with sampled integer heights. Flat mode sets zero tangents; cardinal mode uses endpoint differences and half the neighboring height difference internally. Sample the piecewise cubic Hermite profile, sum segment lengths, and emit normalized SVG coordinates.^[1]

Delegated operations used for this result: cubic hermite. Their calculation or parsing conventions apply to the corresponding result fields.^[2]

Input field	Meaning and units	Accepted input
controlCount	Control Count	Required. Safe integer; minimum 2; maximum 64.
width	Width	Required. Finite number; strictly above 0.
minimumHeight	Minimum Height	Required. Safe integer.
maximumHeight	Maximum Height	Required. Safe integer.
tangentMode	Tangent Mode	Required. Text; one of "flat", "cardinal".
subdivisions	Subdivisions	Required. Safe integer; minimum 1; maximum 64.
seed	Optional numeric seed; takes precedence over context randomness. Without either, use the fixed tool.io default seed.	Optional. Safe integer.

Output field	Interpretation	Returned shape
controls	Controls	Required. Array of Object; no unknown keys.; minimum items 2; maximum items 64.
controls[].x	X	Required. Finite number.
controls[].y	Y	Required. Finite number.
samples	Samples	Required. Array of Object; no unknown keys.; minimum items 2; maximum items 4033.
samples[].x	X	Required. Finite number.
samples[].y	Y	Required. Finite number.
sampledPathLength	Sampled Path Length	Required. Finite number; minimum 0.
svg	Svg	Required. Text; minimum UTF-16 length 1; maximum UTF-16 length 262144.
randomness	Replay metadata: source is seed or context; seed is the normalized 32-bit seed or null for a context source.	Required. Object; no unknown keys.
randomness.seed	Optional numeric replay seed; normalization and precedence are explained below.	Required. Safe integer. or Null.
randomness.source	Source	Required. Text; one of "context", "seed".

An explicit safe-integer seed takes precedence over injected context randomness and is normalized to an unsigned 32-bit integer. With no seed and no context source, replay uses the fixed tool.io default seed. A context source must return finite values from zero inclusive to one exclusive; its advancing state must be retained separately. randomness records the source and normalized seed, or null for context. These generators are not cryptographic random sources.

json

{
  "input": {
    "controlCount": 3,
    "width": 4,
    "minimumHeight": 0,
    "maximumHeight": 4,
    "tangentMode": "flat",
    "subdivisions": 2,
    "seed": 42
  },
  "output": {
    "controls": [
      {
        "x": 0,
        "y": 3
      },
      {
        "x": 2,
        "y": 2
      },
      {
        "x": 4,
        "y": 4
      }
    ],
    "samples": [
      {
        "x": 0,
        "y": 3
      },
      {
        "x": 1,
        "y": 2.5
      },
      {
        "x": 2,
        "y": 2
      },
      {
        "x": 3,
        "y": 3
      },
      {
        "x": 4,
        "y": 4
      }
    ],
    "sampledPathLength": 5.06449510224598,
    "svg": "<svg xmlns=\"http://www.w3.org/2000/svg\" viewBox=\"0 0 1 1\" preserveAspectRatio=\"none\"><polyline points=\"0,0.5 0.25,0.75 0.5,1 0.75,0.5 1,0\" fill=\"none\" stroke=\"#245B36\" stroke-width=\"0.005\"/></svg>",
    "randomness": {
      "seed": 42,
      "source": "seed"
    }
  }
}

Limitations and assumptions

Reported length approximates the sampled polyline, not exact curve arc length. Height interpolation inherits the delegated numeric precision. Coordinates must remain distinguishable; this artwork is not a surveyed terrain model.
A replay requires the same complete input and implementation. Randomized construction does not guarantee uniform coverage of every feasible output; finite samples can repeat unless a distinct-selection rule is explicitly stated.
The field tables state structural bounds; cross-field constraints and bounded search or output budgets also apply. Unknown keys are rejected where the object contract disallows them. Input errors are distinct from null fields and deliberate invalid controls in a successful output.

Alternative or Complementary methods

For a supplied example, inspect the returned construction or delegated check directly. To evaluate a consumer, also test cases chosen for its own boundaries; a generated finite corpus does not establish exhaustive coverage.

References

Tool behavior and example: Random Terrain Profile Generator — tool.io
Calculation or validation: interpolation/cubic-hermite — tool.io

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