Cesium-Prequel/Specs/Core/EarthOrientationParametersSpec.js

import { defined } from "../../Source/Cesium.js";
import { EarthOrientationParameters } from "../../Source/Cesium.js";
import { JulianDate } from "../../Source/Cesium.js";
import { TimeStandard } from "../../Source/Cesium.js";

describe("Core/EarthOrientationParameters", function () {
  var officialLeapSeconds;

  beforeAll(function () {
    officialLeapSeconds = JulianDate.leapSeconds.slice(0);
  });

  afterEach(function () {
    JulianDate.leapSeconds = officialLeapSeconds.slice(0);
  });

  it("adds leap seconds found in the data by default", function () {
    var eop = new EarthOrientationParameters({
      data: {
        columnNames: [
          "dateIso8601",
          "modifiedJulianDateUtc",
          "xPoleWanderRadians",
          "yPoleWanderRadians",
          "xCelestialPoleOffsetRadians",
          "yCelestialPoleOffsetRadians",
          "ut1MinusUtcSeconds",
          "taiMinusUtcSeconds",
          "lengthOfDayCorrectionSeconds",
        ],
        samples: [
          "2011-08-25T00:00:00Z",
          55798.0,
          2.117957047295119e-7,
          2.111518721609984e-6,
          3.393695767766752e-11,
          3.3452143996557983e-10,
          -0.2908948,
          34.0,
          -2.956e-4,
          "2011-08-26T00:00:00Z",
          55799.0,
          2.193297093339541e-7,
          2.115460256837405e-6,
          -8.241832578862112e-11,
          5.623838700870617e-10,
          -0.29065,
          34.5,
          -1.824e-4,
          "2011-08-27T00:00:00Z",
          55800.0,
          2.262286080161428e-7,
          2.1191157519929706e-6,
          -3.490658503988659e-10,
          6.981317007977318e-10,
          -0.2905572,
          34.5,
          1.9e-6,
          "2011-08-28T00:00:00Z",
          55801.0,
          2.3411652660779493e-7,
          2.122751854601292e-6,
          -6.205615118202061e-10,
          7.853981633974483e-10,
          -0.2907007,
          34.5,
          2.695e-4,
        ],
      },
    });
    expect(eop).not.toBeNull();

    var leapSeconds = JulianDate.leapSeconds;
    expect(leapSeconds.length).toBe(officialLeapSeconds.length + 1);

    var newDate = new JulianDate(2455799.5, 34.5, TimeStandard.TAI);
    var foundNew = false;
    var previousDate;

    for (var i = 0, len = leapSeconds.length; i < len; ++i) {
      var leapSecond = leapSeconds[i];
      if (leapSecond.julianDate.equals(newDate)) {
        foundNew = true;
      }

      if (defined(previousDate)) {
        expect(
          JulianDate.compare(previousDate, leapSecond.julianDate)
        ).toBeLessThan(0);
      }

      previousDate = leapSecond.julianDate;
    }

    expect(foundNew).toBe(true);
  });

  it("does not add leap seconds if told not to do so", function () {
    var eop = new EarthOrientationParameters({
      addNewLeapSeconds: false,
      data: {
        columnNames: [
          "dateIso8601",
          "modifiedJulianDateUtc",
          "xPoleWanderRadians",
          "yPoleWanderRadians",
          "xCelestialPoleOffsetRadians",
          "yCelestialPoleOffsetRadians",
          "ut1MinusUtcSeconds",
          "taiMinusUtcSeconds",
          "lengthOfDayCorrectionSeconds",
        ],
        samples: [
          "2011-08-25T00:00:00Z",
          55798.0,
          2.117957047295119e-7,
          2.111518721609984e-6,
          3.393695767766752e-11,
          3.3452143996557983e-10,
          -0.2908948,
          35.0,
          -2.956e-4,
          "2011-08-26T00:00:00Z",
          55799.0,
          2.193297093339541e-7,
          2.115460256837405e-6,
          -8.241832578862112e-11,
          5.623838700870617e-10,
          -0.29065,
          36.0,
          -1.824e-4,
          "2011-08-27T00:00:00Z",
          55800.0,
          2.262286080161428e-7,
          2.1191157519929706e-6,
          -3.490658503988659e-10,
          6.981317007977318e-10,
          -0.2905572,
          36.0,
          1.9e-6,
          "2011-08-28T00:00:00Z",
          55801.0,
          2.3411652660779493e-7,
          2.122751854601292e-6,
          -6.205615118202061e-10,
          7.853981633974483e-10,
          -0.2907007,
          36.0,
          2.695e-4,
        ],
      },
    });
    expect(eop).not.toBeNull();

    var leapSeconds = JulianDate.leapSeconds;
    expect(leapSeconds.length).toBe(officialLeapSeconds.length);
  });

  describe("loading eop", function () {
    function linearInterp(dx, y1, y2) {
      return y1 + dx * (y2 - y1);
    }

    it("interpolates data correctly under normal circumstances", function () {
      var eopDescription = {
        url: undefined,
        data: {
          columnNames: [
            "dateIso8601",
            "modifiedJulianDateUtc",
            "xPoleWanderRadians",
            "yPoleWanderRadians",
            "xCelestialPoleOffsetRadians",
            "yCelestialPoleOffsetRadians",
            "ut1MinusUtcSeconds",
            "taiMinusUtcSeconds",
            "lengthOfDayCorrectionSeconds",
          ],
          samples: [
            "2011-07-01T00:00:00Z",
            55743.0,
            2.117957047295119e-7,
            2.111518721609984e-6,
            3.393695767766752e-11,
            3.3452143996557983e-10,
            -0.2908948,
            34.0,
            -2.956e-4,
            "2011-07-02T00:00:00Z",
            55744.0,
            2.193297093339541e-7,
            2.115460256837405e-6,
            -8.241832578862112e-11,
            5.623838700870617e-10,
            -0.29065,
            34.0,
            -1.824e-4,
            "2011-07-03T00:00:00Z",
            55745.0,
            2.262286080161428e-7,
            2.1191157519929706e-6,
            -3.490658503988659e-10,
            6.981317007977318e-10,
            -0.2905572,
            34.0,
            1.9e-6,
            "2011-07-04T00:00:00Z",
            55746.0,
            2.3411652660779493e-7,
            2.122751854601292e-6,
            -6.205615118202061e-10,
            7.853981633974483e-10,
            -0.2907007,
            34.0,
            2.695e-4,
          ],
        },
      };

      var eop = new EarthOrientationParameters(eopDescription);

      var date = JulianDate.fromIso8601("2011-07-02T12:34:56Z");
      var result = eop.compute(date);
      var nColumns = eopDescription.data.columnNames.length;
      var x0 = eopDescription.data.samples[1 * nColumns + 2];
      var x1 = eopDescription.data.samples[2 * nColumns + 2];
      var dt =
        JulianDate.secondsDifference(
          date,
          JulianDate.fromIso8601(eopDescription.data.samples[nColumns])
        ) / 86400.0;
      var expected = linearInterp(dt, x0, x1);
      expect(result.xPoleWander).toEqualEpsilon(expected, 1e-22);
      x0 = eopDescription.data.samples[1 * nColumns + 3];
      x1 = eopDescription.data.samples[2 * nColumns + 3];
      expected = linearInterp(dt, x0, x1);
      expect(result.yPoleWander).toEqualEpsilon(expected, 1e-22);
      x0 = eopDescription.data.samples[1 * nColumns + 4];
      x1 = eopDescription.data.samples[2 * nColumns + 4];
      expected = linearInterp(dt, x0, x1);
      expect(result.xPoleOffset).toEqualEpsilon(expected, 1e-22);
      x0 = eopDescription.data.samples[1 * nColumns + 5];
      x1 = eopDescription.data.samples[2 * nColumns + 5];
      expected = linearInterp(dt, x0, x1);
      expect(result.yPoleOffset).toEqualEpsilon(expected, 1.0e-22);
      x0 = eopDescription.data.samples[1 * nColumns + 6];
      x1 = eopDescription.data.samples[2 * nColumns + 6];
      expected = linearInterp(dt, x0, x1);
      expect(result.ut1MinusUtc).toEqualEpsilon(expected, 1.0e-15);
    });

    it("interpolates UT1 correctly over a leap second", function () {
      var eopDescription = {
        url: undefined,
        data: {
          columnNames: [
            "dateIso8601",
            "modifiedJulianDateUtc",
            "xPoleWanderRadians",
            "yPoleWanderRadians",
            "xCelestialPoleOffsetRadians",
            "yCelestialPoleOffsetRadians",
            "ut1MinusUtcSeconds",
            "taiMinusUtcSeconds",
            "lengthOfDayCorrectionSeconds",
          ],
          samples: [
            "2008-12-30T00:00:00Z",
            54830.0,
            -4.6702101901281595e-8,
            6.989752766028624e-7,
            -7.80550026586353e-10,
            -1.052045688007693e-9,
            -0.5911461,
            33.0,
            5.7e-4,
            "2008-12-31T00:00:00Z",
            54831.0,
            -6.507169227852191e-8,
            7.02873178598983e-7,
            -7.80550026586353e-10,
            -1.8907733563271904e-9,
            -0.59187,
            33.0,
            8.303e-4,
            "2009-01-01T00:00:00Z",
            54832.0,
            -8.25443773457096e-8,
            7.089575902969077e-7,
            -8.047907106418297e-10,
            -2.0604581447155277e-9,
            0.4071533,
            34.0,
            0.0010604,
            "2009-01-02T00:00:00Z",
            54833.0,
            -9.884381330461219e-8,
            7.147559619229779e-7,
            -8.435758051305926e-10,
            -1.8228994409718553e-9,
            0.4059739,
            34.0,
            0.0012279,
            "2009-01-03T00:00:00Z",
            54834.0,
            -1.1269009203710055e-7,
            7.226826656091187e-7,
            -9.066015836748322e-10,
            -1.5029224114395617e-9,
            0.404674,
            34.0,
            0.0013014,
          ],
        },
      };

      var eop = new EarthOrientationParameters(eopDescription);
      var dateAtLeapSecond = JulianDate.fromIso8601("2009-01-01T00:00:00Z");
      var dateSlightlyBefore = JulianDate.addSeconds(
        dateAtLeapSecond,
        -1.0,
        new JulianDate()
      );
      var dateSlightlyAfter = JulianDate.addSeconds(
        dateAtLeapSecond,
        1.0,
        new JulianDate()
      );
      var nColumns = eopDescription.data.columnNames.length;
      var x0 = eopDescription.data.samples[1 * nColumns + 6];
      var x1 = eopDescription.data.samples[2 * nColumns + 6];
      var x2 = eopDescription.data.samples[3 * nColumns + 6];
      var t0 = JulianDate.fromIso8601(eopDescription.data.samples[nColumns]);
      var t1 = JulianDate.fromIso8601(
        eopDescription.data.samples[2 * nColumns]
      );
      var dt =
        JulianDate.secondsDifference(dateSlightlyBefore, t0) / (86400.0 + 1);
      // Adjust for leap second when interpolating
      var expectedBefore = linearInterp(dt, x0, x1 - 1);
      var resultBefore = eop.compute(dateSlightlyBefore);
      expect(resultBefore.ut1MinusUtc).toEqualEpsilon(expectedBefore, 1.0e-15);
      var expectedAt = eopDescription.data.samples[2 * nColumns + 6];
      var resultAt = eop.compute(dateAtLeapSecond);
      expect(resultAt.ut1MinusUtc).toEqualEpsilon(expectedAt, 1.0e-15);
      dt = JulianDate.secondsDifference(dateSlightlyAfter, t1) / 86400.0;
      var expectedAfter = linearInterp(dt, x1, x2);
      var resultAfter = eop.compute(dateSlightlyAfter);
      expect(resultAfter.ut1MinusUtc).toEqualEpsilon(expectedAfter, 1.0e-15);
      // Check to make sure the values are (correctly) discontinuous
      expect(
        Math.abs(resultBefore.ut1MinusUtc - resultAfter.ut1MinusUtc) > 0.5
      ).toEqual(true);
    });
  });
});