Seatruth evidence
reasonable performances can be achieved,
provided the image is worthy of shallow water work.

• Use of Jerlov's data for optical calibration  really does a good job:
  • see how the majority of pixels are assigned a retrieved depth which is reasonably accurate
  • accuracy is reasonable
  • precision decreases as the bottom depth increases
• But foul waters at particular locations cause severe artifacts:
  • where deep water radiance Lsw is underestimated (bloom, diffusion by suspended particles), retrieved depth is underestimated.
  • this causes bad water column corrected bottom signatures, which must be identified as unacceptable by the practioner.

      

XYZ textfile for depth sounding lines Each separate depth sounding line starts with a header Any number of profiles Any number of points in each profile > LineName_1 - X    Y    Z X    Y    Z  ..... > LineName_2 - X    Y    Z X    Y    Z X    Y    Z  ..... see negril85XYZ-3lines.txt

Best is one shapefile in the same georeferencing as the spectral image with an attribute for Depth in meters, positive comprised of any number of separate profiles/polylines any number of depth points per profile/polyline each polyline may be comprised of several segments 4SM shall call shp2text to read this shapefile for XUTM   YUTM   Z_in_meters name the separate profiles with suffix A to Z convert into a suitable text file as above

2 - Depth points : formatted as a one-line dataset

3 - DTM for gridded digital terrain model