Accuracy & Process

Accuracy and process

Survey-grade work is a process, not a single flight. Every project moves through field acquisition, processing, quality assurance, and delivery. When you need documented compliance with ASPRS Positional Accuracy Standards, Version 2.0, we establish ground control, withhold independent checkpoints from processing, and issue an accuracy report.

Field acquisition

Flights are planned against the accuracy class, sensor, and site conditions agreed during scoping.

Aerial data is collected with RTK or PPK corrections from a multi-band GNSS base and rover.
Ground control points and independent checkpoints are established on every project where an ASPRS accuracy assessment is required.
Numbered ground targets and, where useful, LiDAR-reflective targets mark control in the imagery and point cloud.
Multispectral missions are flown with the sensor’s downwelling light sensor and a calibrated reflectance panel so vegetation indices remain radiometrically consistent.
Thermal missions are scheduled for the right ambient conditions — typically nighttime or a low sun angle for roof moisture work.
Operations in controlled airspace are flown only with the appropriate authorization (see Airspace and LAANC below).

Processing

LiDAR and photogrammetry data are processed to produce the initial point cloud and trajectory.
The point cloud is refined to correct residual strip-to-strip misalignment.
Classification, contour generation, orthomosaic production, and GIS formatting are completed in house.
Multispectral imagery is calibrated to reflectance values, corrected, and built into orthomosaics without discarding the underlying data. NDVI and NDRE analysis and zone classification follow.
Thermal data is processed into Float32 orthomosaics and analyzed for moisture, electrical, or envelope anomalies, depending on the mission.

We do not send your project out to a generic processing queue and hope the defaults are good enough. The same practice that plans the flight also owns the classification, the contours, and the report.

Quality assurance and delivery

Horizontal and vertical accuracy are evaluated separately against independent checkpoints that were not used in processing. That is the method set out in ASPRS Positional Accuracy Standards for Digital Geospatial Data, Version 2.0, which define accuracy in absolute terms (RMSE) rather than by map scale.

A formal accuracy report based on those independent checkpoints is prepared for any project where you need documented ASPRS compliance. Deliverables are packaged in the formats listed on the Services page and transmitted with the report, site photographs, and any tile index required for a larger site.

ASPRS v2.0

ASPRS accuracy classes

Target class is selected with you during scoping. Meeting a class depends on proper ground control, independent checkpoints, sensor choice, and flying height — it is not automatic on every flight. Common target classes we work to are:

Common ASPRS target accuracy classes
Class	Horizontal accuracy	Vertical accuracy
Class I	≤ 5 cm RMSE	≤ 5 cm RMSE
Class II	≤ 10 cm RMSE	≤ 10 cm RMSE
Class III	≤ 15–20 cm RMSE	≤ 15–20 cm RMSE

If your specifications use a different statement of accuracy, include that when you email us.

Accuracy report

When documented compliance is required, the accuracy report presents the independent checkpoint comparison, the resulting horizontal and vertical RMSE, and the ASPRS class assessed for the product. Keep it with the deliverables so reviewing engineers and surveyors can see how the data was checked.

Airspace and LAANC

Standard LAANC authorization is obtained for flights inside controlled airspace. When a mission falls outside standard LAANC limits, a Further Coordination request is submitted before we fly. Flight dates stay flexible around weather and authorization windows.

Licensed survey statement

GruntworX Geospatial Solutions provides survey-grade geospatial data intended to meet ASPRS Positional Accuracy Standards for Digital Geospatial Data, Version 2.0, when proper ground control and independent checkpoints are established. Our products are designed to support engineers, surveyors, and other licensed professionals on work that does not require a Professional Surveyor and Mapper (PSM) seal. GruntworX is not a licensed survey firm, and our deliverables are not sealed surveys. Work that legally requires a PSM seal should be contracted through a licensed Professional Surveyor and Mapper.

Ready to scope your accuracy requirements?

Email us with the site, the accuracy you need, and the products you want delivered.

Email Dave@gxgsolutions.com