5.12: Drone Thermography Specification Tables
- Page ID
- 57857
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Term |
Description |
Level I Relevance |
|
Ground Sample Distance (GSD) |
The real-world ground area represented by one pixel in a thermal image |
Determines smallest detectable feature |
|
Smaller GSD |
Higher detail per pixel |
Preferred for inspections |
|
Larger GSD |
Less detail per pixel |
Risk of averaging errors |
|
GSD Dependency |
Affected by altitude, sensor resolution, and lens |
Must be considered before flight |
Key Principle:
If a target does not occupy multiple pixels, its temperature reading may be unreliable.
|
Sensor Resolution |
Common Lens FOV |
Typical Platforms |
Level I Notes |
|
320 × 256 |
~45° |
Entry-level UAS |
Limited small-target detection |
|
640 × 512 |
~45° |
Professional UAS |
Preferred for inspections |
|
640 × 512 |
~25° (telephoto) |
Industrial UAS |
Better detail at altitude |
|
Flight Altitude (AGL) |
Approx. GSD |
Practical Impact |
|
65 ft |
~6–7 cm / pixel |
Good for small components |
|
130 ft |
~12–14 cm / pixel |
Moderate detail |
|
200 ft |
~18–20 cm / pixel |
Small anomalies may be lost |
|
260 ft |
~25–28 cm / pixel |
Pattern recognition only |
Level I Guidance:
At higher altitudes, thermography becomes a qualitative screening tool, not a measurement-focused one.
|
Flight Altitude (AGL) |
Approx. GSD |
Practical Impact |
|
65 ft |
~3–4 cm / pixel |
High detail |
|
130 ft |
~6–7 cm / pixel |
Reliable inspections |
|
200 ft |
~9–10 cm / pixel |
Moderate detail |
|
260 ft |
~12–14 cm / pixel |
Acceptable screening |
Instructor Note:
A 640-resolution sensor roughly doubles usable inspection altitude compared to 320 sensors.
|
Lens FOV |
Altitude |
Approx. GSD |
Benefit |
Limitation |
|
45° |
40 m |
~6–7 cm |
Wide coverage |
Less detail |
|
25° |
40 m |
~3–4 cm |
High detail |
Narrow coverage |
|
25° |
80 m |
~6–7 cm |
Maintains detail |
Reduced situational awareness |
|
Pixel Coverage |
Measurement Reliability |
Level I Interpretation |
|
< 1 pixel |
Invalid |
Do not report |
|
1–2 pixels |
Poor |
Screening only |
|
3–5 pixels |
Fair |
Caution advised |
|
5+ pixels |
Good |
Preferred |
Best Practice:
Targets should fill at least 5 × 5 pixels for meaningful temperature data.
|
Application |
Recommended GSD |
Typical Altitude (640 Sensor) |
|
Electrical components |
≤ 5 cm |
20–30 m |
|
Solar modules |
5–10 cm |
30–60 m |
|
Roof inspections |
8–15 cm |
40–80 m |
|
Building envelopes |
10–20 cm |
50–100 m |
|
Large infrastructure |
≥ 15 cm |
80+ m |
Level I Reminder – Drone Thermography
Altitude, resolution, and lens choice directly affect thermal image quality.
Level I thermographers follow approved flight and inspection procedures and document altitude, sensor type, and environmental conditions.