Archery Apprentice Documentation

Target Face Visualization

3 min read

Target Face Visualization

Overview

The Target Face Visualization component provides real-time visual analysis of arrow distribution patterns. It renders arrows on a target face canvas with statistical overlays to help archers understand their shooting patterns.

Component: RoundTargetFaceVisualization.kt
Location: app/src/main/java/com/archeryapprentice/ui/roundScoring/components/

Key Features

🎯 Arrow Rendering

  • Color-coded scoring values
  • Multiple scoring systems (10-ring, 5-ring)
  • Multiple target sizes (40cm, 80cm, 122cm)
  • Normalized coordinate system (-1 to 1)

📊 Statistical Overlays

Requires 3+ arrows with coordinates to display:

  1. Group Center Crosshair

    • Shows calculated arrow group center
    • May differ from target center

  2. Spread Oval (Ellipse)

    • Visualizes directional arrow distribution
    • Black outline + green inner ring
    • Shape adapts to horizontal vs vertical spread

  3. Bias Lines

    • Red line: Horizontal bias (left/right)
    • Blue line: Vertical bias (high/low)
    • Shows systematic offset from target center

⚠️ Coverage Warnings

  • < 50%: Hides visualization (insufficient data)
  • 50-89%: Shows with warning banner
  • ≥ 90%: Shows without warnings

Why Ellipse? (Not Circle)

Traditional metrics use a single radius → always produces a circle.

Real arrow distributions show directional patterns:

  • Vertical spread: Arrows at 12 & 6 o’clock → tall oval
  • Horizontal spread: Arrows at 3 & 9 o’clock → wide oval
  • Mixed spread: Different amounts in each direction

Ellipse accurately represents non-circular distributions.

Calculation Method

Directional Spreads

1. Group Center = average(x, y coordinates)

2. Horizontal Spread = max(|arrow.x - groupCenter.x|)
   
3. Vertical Spread = max(|arrow.y - groupCenter.y|)

4. Bias = groupCenter offset from target center (0,0)

Oval Dimensions

ovalWidth = horizontalSpread × targetRadius × 2
ovalHeight = verticalSpread × targetRadius × 2

Interpretation Guide

Spread Patterns

🔵 Circular (horizontal ≈ vertical)

  • Means: Balanced form, no directional issues
  • Action: Focus on reducing overall group size

⬆️ Tall Oval (vertical >> horizontal)

  • Means: Vertical inconsistency
  • Causes: Anchor height, release timing, bow cant
  • Action: Vertical consistency drills

↔️ Wide Oval (horizontal >> vertical)

  • Means: Horizontal inconsistency
  • Causes: Bow arm alignment, release direction, grip torque
  • Action: Horizontal alignment training

Bias Patterns

No Bias (minimal/no lines)

  • Sight properly adjusted ✅
  • Good centering ✅

Horizontal Bias (Red Line)

  • Right: Group right of center → adjust windage
  • Left: Group left of center → adjust windage

Vertical Bias (Blue Line)

  • High: Group above center → adjust elevation
  • Low: Group below center → adjust elevation

Combined Bias (Both Lines)

  • Major sight adjustment needed
  • Or form correction required

Data Requirements

Minimums

  • Display arrows: 1+ with coordinates
  • Show overlays: 3+ with coordinates
  • Coverage: 50%+ must have coordinates

Coordinate System

  • Range: -1.0 (edge) to 1.0 (edge)
  • Center: (0, 0)
  • Storage: ArrowScore model fields

Grouping Quality

Based on spread radius:

  • Excellent: < 10% of target radius
  • Tight: 10-20%
  • Moderate: 20-30%
  • Wide: > 30%

Measurements scaled to real dimensions:

  • 40cm target: spread × 20cm
  • 80cm target: spread × 40cm
  • 122cm target: spread × 61cm

Example: “Tight grouping: 3.5cm spread, slight right bias”

Test Coverage

42 unit tests covering:

  • Coordinate coverage (6 tests)
  • Statistical calculations (8 tests)
  • Directional spreads (6 tests)
  • Component rendering (10 tests)
  • Statistical descriptions (12 tests)

Key scenarios:

  • ✅ Vertical spread (tall oval)
  • ✅ Horizontal spread (wide oval)
  • ✅ Mixed spreads
  • ✅ Circular patterns
  • ✅ Bias detection
  • ✅ Coverage thresholds

Performance

  • Calculations: O(n), very fast
  • Rendering: Optimized for real-time
  • Tested with: 100+ arrows (< 1 second)
  • Large datasets: 200+ arrows maintain performance

Future Ideas

  • 🎯 Outlier detection (highlight errors)
  • 📊 Historical comparison overlays
  • 📈 Confidence interval bands
  • 🌬️ Wind direction indicators
  • 💾 Export as images

Created: 2025-10-11
Test Coverage: 42/42 passing
Status: ✅ Stable

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