Location/Site
Encinitas Community Park NE ball field bathrooms
(33°01’53.25″N 117°16’47.57″W)
Date
Jun 29th, 2026
Time
07:52 AM
Executive Summary
Mission Objective
Develop a baseline spatial dataset of a municipal park building using nadir-only photogrammetry. The mission was designed to evaluate the effectiveness of an automated lawnmower of 4 longitudinal passes on a SW-NE axis at 120’ AGL in producing an orthomosaic, a dense point cloud, a textured mesh, and a digital surface model, while documenting the strengths and limitations of consumer-grade GNSS positioning.
This dataset serves as the control mission for future comparisons involving crosshatch flight patterns and orbital oblique imagery. A nadir-only lawnmower grid was selected to establish a repeatable baseline dataset emphasizing horizontal accuracy and complete ground coverage.
Intended Applications
- Site documentation
- Relative dimensional verification
- Pavement, asset, and vegetation inventory
- Existing conditions documentation
- Baseline comparison for future site monitoring
- Capture strategy evaluation
Mission Planning
Airspace
- Class G, Uncontrolled
- No TFRs
Weather Conditions
- Temperature: 66.2º F
- Wind: 7.4 mph, 211º SSW
- Cloud Cover: OVC, 1000’ AGL
- Lighting Conditions: Overcast
Mission Success Criteria
- Complete image alignment
- Continuous orthomosaic coverage
- Minimal visible block deformation
- Relative measurements within ±5% of field measurements
- Clearly documented dataset limitations
- Safe and complete mission without any deviations or conflicts
Data Capture Strategy
Flight Parameters
| Parameter | Value |
|---|---|
| Flight Pattern | Automated Lawnmower Grid (manually created) |
| Altitude | 120 ft AGL |
| Flight Duration | 5m 08s |
| Camera Angle | Nadir (-90°) |
| Front Overlap | 80% |
| Side Overlap | 65% |
| Speed | 3.13 mph |
| Photo Interval | 5 sec |
| ISO | 100 |
| Shutter | 1/640 sec |
| Aspect Ratio | 4:3 |
| Image Capture Count | 48 JPEG (8064 x 6048) |
| Lighting | Uniform Overcast |
Processing Summary
| Metric | Result |
|---|---|
| Images Reconstructed | 47/48 shots (97.9%) |
| Average Reprojection Error | 1.28 px |
| Average GSD | 0.8 cm/pixel |
| Sparse Points | 37690 (96.5%) |
| Dense Points | 3.48 million |
| GPS Source/ CRS | Consumer GNSS (No RTK/PPK) |
| GPS Error RMS | .25 |
| Outputs | Orthomosaic, DSM, DTM, Point Cloud, Mesh |
Interpretation
Orthomosaic
Produced complete visual coverage of the project area with no significant stitching failures.
Suitable for documentation, visual inspection, asset inventory, and approximate measurements.
Point Cloud
Successfully reconstructed terrain, pavement, vegetation, and major structures. Building facades, vehicle sides, and tall vegetation were incompletely represented due to the nadir acquisition strategy.
Textured Mesh
Produced a coherent three-dimensional representation of the site. Quality decreased beneath mature trees and along vertical surfaces where image geometry was insufficient or nonexistent.
DSM
Successfully represented overall site topography, including the gradual elevation increase across the parking lot.
Vegetation and building heights were preserved as expected in a Digital Surface Model.
Quality Validation
Relative Measurement Validation
Seven independent field measurements were compared against the reconstructed model.
Results demonstrated relative dimensional agreement generally within approximately 2–4%, with one outlier associated with a table that abutted a tall fence, resulting in incomplete capture and measurement inaccuracy.
Interpretation
| Location/object | Lat/Long Coordinates | Actual (inches) | Model (inches) | Delta (Inches) | Signed Error (%) | Model Used |
|---|---|---|---|---|---|---|
| Midway landing on the north stairs (depth) | 33°01'53.67"N 117°16'47.57"W | 48.75 | 51.36 | 2.61 | 5.35% | Ortho |
| Building pillar on NW | 33°01'53.41"N 117°16'47.78"W | 31.75 | 33.96 | 2.21 | 6.96% | Ortho |
| Front face men’s bathroom | 33°01'53.09"N 117°16'47.61"W | 120.375 | 122.64 | 2.265 | 1.88% | Ortho |
| Manhole cover (parking lot) | 33°01'53.74"N 117°16'47.04"W | 28.875 | 29.64 | 0.765 | 2.65% | Ortho |
| Asphalt patch parking lot | 33°01'52.96"N 117°16'46.88"W | 48.625 | 50.768 | 2.143 | 4.41% | Ortho |
| Top of stairs across pavers (West side, not including white exp joint) | 33°01'53.0"N 117°16'48.1"W | 139.063 | 139.32 | 0.257 | 0.18% | Ortho |
| Tactile strip near HDCP parking (south) | 33°01'52.1"N 117°16'46.8"W | 94.5 | 94.44 | -0.06 | -0.06% | Ortho |
| Steps to pavers (south) | 33°01'52.4"N 117°16'47.5"W | 34.375 | 31.44 | -2.935 | -8.54% | Ortho |
| Concrete slab near south ballfield (southwest, include white exp joint) | 33°01'52.7"N 117°16'48.3"W | 94 | 94.2 | 0.2 | 0.21% | Ortho |
| Concrete slab near north ballfield (northwest, include white exp joint) | 33°01'53.6"N 117°16'48.5"W | 116.5 | 117.49 | 0.99 | 0.85% | Ortho |
| Dual manhole covers, lower level (northwest) | 33°01'53.5"N 117°16'47.8"W | 43.375 | 45 | 1.625 | 3.75% | Ortho |
| Error Calculation | Value |
|---|---|
| Mean Signed Error (Bias) | 1.60% |
| Mean Absolute Error (MAE) | 1.46 |
| Mean Absolute Percent Error (MAPE) | 3.17% |
| Root Mean Square Error (RMSE) | 1.77 |
This dataset is suitable for educational use and approximate measurements but lacks the positional accuracy required for engineering, surveying, or legal-grade geospatial analysis.
Quality Assessment
Strengths
- Complete image reconstruction
- Consistent relative measurement accuracy
- Uniform lighting enhanced detail
- Repeatable data capture workflow established
Limitations
- Absolute positional accuracy is limited by the lack of GNSS corrections
- Missing vertical surfaces and tree occlusions resulting from nadir capture
- Vehicle movement introduced localized artifacts
- Observable large-scale block deformation on the sidewalk point cloud
Conclusion
The 2D orthomosaic provides adequate visual coverage of the site and demonstrates reasonable relative dimensional consistency, with field-verified measurements generally within 2–4% of observed values. There were significant stitching artifacts on the building’s pitched metal roof and on horizontal surfaces adjacent to vertical surfaces. The narrow palm trees did not render well with occlusion of the trunks and branches.
The point cloud did not reconstruct well. Most of the vertical surfaces were occluded, and many of the 90º corners, such as curbs, stair steps, and wall bases, were very rounded. The building’s corrugated metal roof was occluded, likely due to poor image stitching.
Overall, this mission, using nadir imagery, did not reconstruct well. This dataset would be adequate only for a rough asset inventory and progress status.
Mission 2B Hypothesis
Nadir crosshatch capture may improve the 2D orthomosaic, but may produce additional stitching issues, similar to how Mission IC introduced more warping and artifacts than the nadir lawnmower capture from Mission 1A. A test will be whether orbital oblique capture provides better vertical surface detail without creating additional stitching issues from multiple camera perspectives and parallax.