Sampling unit size
Prior to this stage ensure you know your image and field data positional:
- ACCURACY - difference between true and actual position
- PRECISION - minimum measured positional distance
Need to consider how you will match your reference data sample unit to your image data, especially in terms of the spatial scale of both data sets, they need to match.
The positional accuracy must be high enough to allow sample units to match image pixels or objects
Options for sample unit size of observations
- Points (pixels)
- Lines
- Areas or polygons
