Ascent and descent values too high

[micrtoeq]

Hi

Ascent and descent values are too high, because they are calculated every 1 to 4 meters. They should be calculated in bigger walking distances. My suggestion is 10 meters.

I have adjusted the source code, which is pasted at the end of this message. Only what I have marked with DGF are changes made by me, the rest is the original. There are two functions in leaflet-elevation.js that are affected: _addData and _addPoint.

Best regards. Daniel.

---

/*

• Parsing data either from GPX or GeoJSON and update the diagram data */ _addData: function(d) { let geom = d && d.geometry; let feat = d && d.type === "FeatureCollection"; let gpx = d && d._latlngs;

      if (geom) {
          switch (geom.type) {
              case 'LineString':
                  this._addGeoJSONData(geom.coordinates);
                  break;
  
              case 'MultiLineString':
                  geom.coordinates.forEach(coords => this._addGeoJSONData(coords));
                  break;
  
              default:
                  console.warn('Unsopperted GeoJSON feature geometry type:' + geom.type);
          }
    //DGF if elevation difference is too small, make ascent and descent equal
    if (Math.abs(this._ascent-this._descent) <= 10)
    {
      this.track_info.descent = this.track_info.ascent;
      this._descent = this.track_info.descent;
    }
    //DGF end
      }
  
      if (feat) {
          d.features.forEach(feature => this._addData(feature));
      }
  
      if (gpx) {
          this._addGPXdata(d._latlngs);
      }
  },

---

/*

• Parse and push a single (x, y, z) point to current elevation profile. */ _addPoint: function(x, y, z) { if (this.options.reverseCoords) { [x, y] = [y, x]; }

      let data = this._data || [];
      let eleMax = this._maxElevation || -Infinity;
      let eleMin = this._minElevation || +Infinity;
      let dist = this._distance || 0;
  //DGF
  let elevDist = this._elevationMesurementDistance || 0;
  //DGF end
      let curr = new L.LatLng(x, y);
      let prev = data.length ? data[data.length - 1].latlng : curr;
  
      let delta = curr.distanceTo(prev) * this._distanceFactor;
  
      dist = dist + Math.round(delta / 1000 * 100000) / 100000;
  //DGF
  elevDist = elevDist + delta;
  //DGF end
  
  // check and fix missing elevation data on last added point
      if (!this.options.skipNullZCoords && data.length > 0) 
  {
          let prevZ = data[data.length - 1].z;
          if (isNaN(prevZ)) {
              let lastZ = this._lastValidZ;
              let currZ = z * this._heightFactor;
              if (!isNaN(lastZ) && !isNaN(currZ)) {
                  prevZ = (lastZ + currZ) / 2;
              } else if (!isNaN(lastZ)) {
                  prevZ = lastZ;
              } else if (!isNaN(currZ)) {
                  prevZ = currZ;
              }
              if (!isNaN(prevZ)) data[data.length - 1].z = prevZ;
              else data.splice(data.length - 1, 1);
          }
      }
  
      z = z * this._heightFactor;
  
      // skip point if it has not elevation
      if (!isNaN(z)) 
  {
          eleMax = eleMax < z ? z : eleMax;
          eleMin = eleMin > z ? z : eleMin;
  
    // calculate new ascent or descent
    //DGF measure elevation only every 10 meters of walking distance
    if (elevDist >= 10 || isNaN(this._lastMeasuredZ))
    {
      elevDist = 0;
      let dz = z - this._lastMeasuredZ ;  //DGF
      if (dz > 0)
      {
        this.track_info.ascent  = (this.track_info.ascent || 0) + dz;  // Total Ascent
        this._ascent = this.track_info.ascent;
      }
      else if (dz < 0)
      {
        this.track_info.descent = (this.track_info.descent || 0) - dz; // Total Descent
        this._descent = this.track_info.descent;
      }
      this._lastMeasuredZ = z;  //DGF
    }
    this._elevationMesurementDistance = elevDist;
    //DGF end
    this._lastValidZ = z;
          // set up last valid z value    
      }
  
      data.push({
          dist: dist,
          x: x,
          y: y,
          z: z,
          latlng: curr
      });
  
      this._data = data;
      this._distance = dist;
      this._maxElevation = eleMax;
      this._minElevation = eleMin;
  },

[morehawes]

@micrtoeq,

DGF are changes made by me, the rest is the original

Appreciated. I will look in to this.

Joe

[morehawes]

Originally discussed here. My thoughts:

I’m not sure what the best way to deal with this will be honestly. The ascent/descent values in question were added in a recent Pull Request and were pulled over from the Leaflet Elevation plugin that Waymark uses… but is not using the most recent version (I believe because of some conflicts I was not able to resolve a long time ago… but can’t quite remember).

So this is quite messy already and any other edits may compound the problem. I agree though that these values should be accurate and that user control over the measurement “frequency” (there is probably a more accurate term) would be a good solution.

Introduced in PR by @MaximeChallon.

Input/help welcome! This may have been discussed/addressed in the source project already so that's worth checking.