getScaleForResolution() {
    const resolution = getPointResolution(
      this.viewState_.projection,
      this.viewState_.resolution,
      this.viewState_.center,
      'm',
    );
    const dpi = this.dpi_ || DEFAULT_DPI;
    const inchesPerMeter = 1000 / 25.4;
    return resolution * inchesPerMeter * dpi;
  }
Returns the appropriate scale for the given resolution and units.
@return {number} The appropriate scale.