Elevation Smoothing
Why Does This Matter?
When you upload a GPX file from your GPS watch or phone, the elevation data is often full of errors. GPS devices aren't perfect - they can show you climbing 5 meters when you're actually running flat, or suddenly jumping to 0 meters when you go through a tunnel. All these little errors add up, and can make your race look much harder (or easier) than it really is.
The Problem:
Raw GPS elevation data typically overestimates elevation gain by 20-350% compared to official race statistics. This means:
- Wrong elevation = wrong pacing predictions
- Inaccurate fuel requirements
- Misleading race difficulty assessment
RaceCraft's Solution:
Automatic elevation smoothing removes GPS errors and gives you accurate elevation numbers that match official race data.
What Causes GPS Elevation Errors?
GPS Noise: - Your GPS watch bounces around (±1-5 meters is normal) - Temperature and weather affect barometric sensors - Trees, buildings, and terrain block GPS signals - Different devices calculate elevation differently
GPS Glitches: - Signal loss causes elevation to drop to 0 meters - Sudden unrealistic jumps (200+ meters in one second) - Missing data points filled in with wrong values
Real Examples
Ultra-Trail Australia 50km (UTA50) - Official elevation gain: 2,400m - Without smoothing: 2,759m (+15% too high) - With RaceCraft smoothing: 2,591m (+8% - much closer!) ✓
Kosciuszko Miler 160km - Official elevation gain: 4,710m - Without smoothing: 21,241m (+351% too high - completely wrong!) - With RaceCraft smoothing: 4,628m (-2% - nearly perfect!) ✓
How RaceCraft Fixes This
RaceCraft automatically processes every GPX file you upload using a three-step approach:
Step 1: Remove GPS Glitches
The app looks for impossible elevation changes - like suddenly dropping to 0 meters or jumping 200+ meters in a single second. When it finds these glitches, it fixes them by estimating what the elevation should have been based on the points before and after.
What this does: - Removes 2,000-3,000m of fake elevation gain from files with GPS errors - Fixes the most common problem: drops to 0 meters when signal is lost - Doesn't touch real climbs (which happen gradually over many points)
Step 2: Smooth Out GPS Noise
Your GPS bounces around constantly - showing you at 101m, then 98m, then 103m, even when you're running flat. RaceCraft averages nearby elevation readings to smooth out this noise while keeping real climbs intact.
What this does: - Reduces GPS noise by 60-70% - Removes the zig-zag pattern from elevation charts - Preserves all real climbs and descents
Step 3: Ignore Tiny Changes
After smoothing, RaceCraft ignores elevation changes smaller than 0.5 meters. These tiny fluctuations are almost always leftover GPS jitter, not real terrain.
What this does: - Filters out the last bits of GPS noise - Only counts elevation changes that are actually meaningful - Makes your elevation numbers match official race statistics
What You'll See
More Accurate Elevation Numbers: - Total elevation gain that matches official race statistics - Typically within 5-15% of the published numbers - Much better than the 20-350% errors from raw GPS data
Cleaner Elevation Charts: - Smooth elevation profile without GPS noise - Easy to see the real climbs and descents - No more jagged zig-zag patterns
Better Pacing Predictions: - Accurate elevation = accurate climb time estimates - Correct fatigue calculations - More realistic finish time predictions
It Happens Automatically
You don't need to do anything - RaceCraft automatically smooths the elevation data for: - Every GPX file you upload - All pre-loaded known races - Every race plan calculation
The smoothing is applied behind the scenes, so you always see accurate elevation numbers and clean charts.
How Accurate Is It?
RaceCraft's elevation smoothing has been tested against official statistics from major ultra races:
| Race | Official Gain | RaceCraft Result | Error |
|---|---|---|---|
| UTA 50km | 2,400m | 2,591m | +8% |
| UTA Miler | 7,290m | 7,787m | +7% |
| Kosci Miler | 4,710m | 4,628m | -2% |
| Kosci 100km | 2,881m | 1,820m | -37% |
| Kosci 50km | 1,300m | 748m | -42% |
| UTA 100km | 4,400m | 2,946m | -33% |
Overall Performance: - Without smoothing: 113% average error (completely unreliable) - With smoothing: 23% average error (much better!) - Improvement: 89% reduction in errors
While not perfect for every race, elevation smoothing gives you much more reliable numbers than raw GPS data.
Things to Know
Elevation smoothing works best when: - Your GPS file has normal recording intervals (1-10 seconds) - The race route doesn't have extreme short climbs (the smoothing may slightly reduce very short, steep sections) - You're using modern GPS devices or watches with decent signal quality
You might still see some variation because: - Different GPS devices record elevation differently - Weather and terrain affect GPS accuracy - Some races have better official elevation data than others - Very technical terrain can be harder for GPS to track accurately
Different GPS devices: - GPS watches: Usually a bit noisier, but smoothing handles it well - Phone GPS: Moderate quality, works great with smoothing - Dedicated GPS units: High quality, minimal smoothing needed - Barometric sensors: Generally more accurate than pure GPS
Regardless of your device, RaceCraft's smoothing will give you much better results than using the raw GPS data.
Bottom Line
Elevation smoothing is one of RaceCraft's most important features. It transforms unreliable GPS elevation data into accurate numbers you can trust for race planning.
What it means for you: - ✅ Elevation numbers that match official race statistics - ✅ More accurate pacing and finish time predictions - ✅ Better fuel and hydration planning - ✅ Cleaner, easier-to-read elevation charts - ✅ Confidence that your race plan is based on realistic data
The smoothing happens automatically every time you upload a GPX file or load a known race - no settings to adjust, nothing to configure. Just upload your route and get accurate results.