# Fact Cards

## Fact #1
- **Statement**: GSD formula: GSD = (pixel_pitch × altitude) / focal_length. This is the fundamental relationship between sensor, optics, altitude, and ground resolution.
- **Source**: Source #3 (Pix4d)
- **Phase**: Phase 2
- **Confidence**: ✅ High

## Fact #2
- **Statement**: Atmospheric turbulence limits ground resolution from 10km altitude to approximately 4.6 cm regardless of optical system quality. Practical achievable limit is 5-8 cm in good conditions.
- **Source**: Source #2 (Optica journal)
- **Phase**: Phase 1
- **Confidence**: ✅ High

## Fact #3
- **Statement**: Vehicle detection requires ~1m GSD. Vehicle type identification requires ~25-50 cm GSD. Detailed vehicle description requires ~10 cm GSD. Per NIIRS scale.
- **Source**: Source #1 (NIIRS Guide)
- **Phase**: Phase 1
- **Confidence**: ✅ High

## Fact #4
- **Statement**: Training data GSD is approximately 10-20 cm/pixel (user confirmed). Target GSD from 10km must match this range.
- **Source**: User confirmation
- **Phase**: Phase 1
- **Confidence**: ✅ High

## Fact #5
- **Statement**: ViewPro A40 Pro achieves GSD of 11.6 cm/pixel from 10km at maximum zoom (170mm FL, 5MP stills). Video (1080p) gives 15.6 cm/pixel. Both within target 10-20 cm range.
- **Source**: Source #4 (Airmobi), calculated
- **Phase**: Phase 2
- **Confidence**: ✅ High (calculation verified)

## Fact #6
- **Statement**: ViewPro Z40K achieves GSD of ~10.3 cm/pixel from 10km at maximum optical zoom (~102mm FL, 25.9MP). Significantly more pixels per frame than A40 Pro (5888 vs 2560).
- **Source**: Source #5 (Viewpro), calculated
- **Phase**: Phase 2
- **Confidence**: ⚠️ Medium (FL estimated from HFOV spec)

## Fact #7
- **Statement**: DJI Zenmuse H30T achieves GSD of ~5.7 cm/pixel from 10km (172mm FL, 40MP). Best integrated zoom camera GSD. But LOCKED to DJI Matrice platform — cannot be used on custom balloon platform without reverse engineering.
- **Source**: Source #7 (DJI)
- **Phase**: Phase 2
- **Confidence**: ✅ High

## Fact #8
- **Statement**: LOONG VT500Rs achieves GSD of ~4.8 cm/pixel from 10km (192mm FL, 48MP). Near atmospheric limit. Price unknown, estimated $10k-20k based on market positioning.
- **Source**: Source #8 (LoongUAV), calculated
- **Phase**: Phase 2
- **Confidence**: ⚠️ Medium (price estimated)

## Fact #9
- **Statement**: Sony α7RV + FE 400-800mm achieves 4.7-9.4 cm/pixel GSD from 10km (400-800mm FL, 61MP, 3.76µm pixel pitch). Best image quality due to full-frame sensor and large pixels. Total weight with lens: 3,140g.
- **Source**: Source #9, #10 (Sony, Gremsy), calculated
- **Phase**: Phase 2
- **Confidence**: ✅ High

## Fact #10
- **Statement**: Viewpro gimbal cameras have documented serial (UART) and TCP/IP control protocols (Viewlink V3.3.3). ArduPilot has native Lua driver for Viewpro gimbals. Suitable for custom platform integration.
- **Source**: Source #11, #12 (Viewpro, ArduPilot)
- **Phase**: Phase 2
- **Confidence**: ✅ High

## Fact #11
- **Statement**: Gremsy T7 gimbal has 3.175kg max payload. Sony α7RV (665g) + FE 400-800mm (2,475g) = 3,140g — at the payload limit with virtually no margin. Risk of unreliable operation.
- **Source**: Source #10 (Gremsy)
- **Phase**: Phase 2
- **Confidence**: ✅ High

## Fact #12
- **Statement**: Balloon payloads experience continuous rotation and pendulum swinging. Active gimbal alone may be insufficient. Passive stabilization through suspension design is critical for image quality.
- **Source**: Source #17 (Iowa State)
- **Phase**: Phase 2
- **Confidence**: ✅ High

## Fact #13
- **Statement**: SIYI ZT30 is a 4-sensor pod ($6,099-7,309) with 30x optical zoom, 8MP, 4K, thermal, and LRF. 9W average power. Achieves ~12 cm/pixel GSD from 10km.
- **Source**: Source #6 (SIYI)
- **Phase**: Phase 2
- **Confidence**: ✅ High

## Fact #14
- **Statement**: A40TR Pro ($7,499-7,999) adds thermal imaging and laser rangefinder to the 40x zoom capability. MIL-STD-810H certified for -40°C to +55°C — best temperature rating among all options.
- **Source**: Source #15 (Airmobi)
- **Phase**: Phase 2
- **Confidence**: ✅ High

## Fact #15
- **Statement**: Sony RX10 IV ($1,700) with 1" sensor and 220mm actual FL achieves ~11 cm/pixel GSD from 10km. Has 20MP resolution (5472×3648). Needs external gimbal for balloon mounting. No documented remote zoom control for UAV integration.
- **Source**: Source #18 (B&H)
- **Phase**: Phase 2
- **Confidence**: ⚠️ Medium (remote control integration unclear)

## Fact #16
- **Statement**: With zoom capability, cameras can be adjusted to match any target GSD within their zoom range. A camera capable of 5cm GSD at max zoom can be zoomed out to deliver 10-20cm GSD matching training data. This means over-capability in GSD is an advantage, not a problem.
- **Source**: Derived from GSD formula
- **Phase**: Phase 2
- **Confidence**: ✅ High

## Fact #17
- **Statement**: Atmospheric haze at 10km reduces image contrast compared to 600-1000m imagery. Even with matched GSD, the AI model may need image preprocessing (dehazing) or fine-tuning for degraded imagery.
- **Source**: Source #2 (atmospheric research)
- **Phase**: Phase 2
- **Confidence**: ⚠️ Medium (impact on specific AI model unknown)
