Appearance
Module 09: Slope Profiler
The Slope Profiler uses your device sensors as a digital clinometer for quick field slope checks. Use it for screening, notes, and site review. For construction staking, legal surveys, or safety-critical measurements, verify results with approved survey equipment.
1. What Is the Slope Profiler?
The Slope Profiler uses your device's built-in accelerometer and gyroscope through the DeviceOrientation API to estimate slope angle at your current position. It is intended for field teams who need a quick indication of terrain gradient for site notes, drainage checks, route review, or accessibility screening.
2. Activating the Profiler
- Navigate to the Map View.
- The Slope Profiler toggle appears in the map toolbar as an orange slope icon.
- Tap the toggle to activate. The profiler enters Ready state.
Sensor Permissions: Your device will request motion sensor access on first use. Grant permission to enable slope readings.
3. The HUD (Heads-Up Display)
When active, a floating HUD gauge appears at the top-center of the map.
Gauge Components
| Element | Description |
|---|---|
| Arc Gauge | A semicircular gauge with a color-coded gradient (green → yellow → orange → red) representing slope severity |
| Needle | Points to the current slope angle and updates as the device moves |
| Angle Readout | Large numeric display: 12.5° — color-coded by severity |
| Grade Percentage | Shows slope as a percentage: 22.2% grade |
| Status | Current state: READY, RECORDING, CALIBRATING |
Color-Coded Ranges
| Angle Range | Color | Meaning |
|---|---|---|
| 0° – 5° | 🟢 Green | Flat / gentle slope |
| 5° – 15° | 🟡 Yellow | Moderate slope |
| 15° – 30° | 🟠 Orange | Steep slope |
| 30°+ | 🔴 Red | Very steep; use caution and verify conditions |
4. Drawing a Cross-Section
Creating Section Stations
- Walk to your starting point on the terrain.
- Tap Draw Section in the action bar.
- Hold your phone level and tap to record a station (slope reading at this point).
- Walk to the next point along the cross-section. Tap again to record.
- Repeat for as many stations as needed.
Station Data
Each recorded station captures:
- Slope angle (degrees)
- Grade percentage
- Relative position along the section
Finishing a Section
Tap Finish (green button) to complete the section. The profile is finalized and the chart updates.
5. Calibration
Before recording a section, calibrate the sensor when possible:
- A calibration overlay appears with a full-screen dark background.
- Place your phone on a known flat surface.
- A calibration dot shows live sensor readings:
- The dot moves as your phone tilts
- When centered (flat), it turns green and pulses
- Tap "Set Zero" to calibrate the zero-point.
- Alternatively, tap "Skip" to proceed without calibration.
- Tap "Redo Section" to restart the section drawing.
Live Calibration Readout
During calibration, live sensor values are displayed:
β 0.3° · γ 0.1°These represent the device's beta (front-back tilt) and gamma (left-right tilt).
6. The Profile Sheet
After recording stations, a bottom sheet slides up from the bottom of the screen, showing:
Sheet Components
| Component | Description |
|---|---|
| Header | "Cross-Section Profile" with station count |
| Chart | A canvas-rendered elevation profile graph showing the slope across all stations |
| Station List | A scrollable list of recorded stations, each showing its index number (color-coded), station info, and slope value |
| Action Bar | Context-sensitive buttons that dock into the sheet when it's open |
Station List Details
Each row in the station list displays:
- A numbered badge with severity-colored background
- Station information (relative distance or label)
- Slope angle value in bold
For sections with many stations (6+), the list switches to a compact layout with smaller text and tighter spacing.
7. Action Bar
The floating action bar provides context-sensitive controls:
| Button | Style | Action |
|---|---|---|
| Draw Section | Orange (primary) | Begin recording a new cross-section |
| Clear | Red (danger) | Delete all recorded stations and reset |
| Finish | Green | Complete the current section |
| Close | Gray circle | Close the action bar and deactivate the profiler |
When the bottom sheet is open, the action bar docks inside the sheet instead of floating on the map.
8. Practical Scenarios
Road Review: A field engineer records several stations across a proposed access route. The profile helps identify sections that may need a closer survey before design decisions are made.
Drainage Check: A site inspector records slope readings along a drainage channel to flag areas that may require additional grading review.
Next: Proceed to Module 10: Map PDF Export to export map documents.