Precision, also called intraswath-precision, is a measurement of repeatability on a hard surface target from within a single pass of a scanner. This metric is primarily a factor of the intrinsic calibration and stability of a scanner. It is also greatly impacted by properties of the measured surface.

Many factors affect the precision of a dataset, most notably:

  • Laser intrinsic quality (Range accuracy, Range Precision, Angular accuracy)

  • Target Reflectivity

  • Range to target

  • Incident angle/scan angle & beam divergence

Measuring Precision

Phoenix LiDAR quantifies precision of systems and datasets during testing by replicating* the USGS methodology and closely conforming with the ASPRS outline.

  1. Utilize a hard surface area within the calibration site, generally a region of flat parking lot or sidewalk.

    1. The area is carefully selected to contain a target of typical real-world signal return at the laser's wavelength, often around 20% reflectivity, avoiding very dark or highly reflective subjects.

  2. Within this area, data is sampled from all overlapping flightlines to consider a variety of scan angles.

  3. Data is processed independently for each flightline according to the USGS methodology.

  4. The per flightline results are summarized by taking an average that characterizes a dataset or scanner.

  5. These evaluations are made for a single AGL (above ground level) at a time and results are conveyed as such.

* PLS typically does not create the vectorized polygons with summarizing attributes as the USGS outline for data delivery.

Industry References

Data providers should always reach an agreement with end users about data quality standards and reporting specifications.