Triton Bathymetry - Manual (Page 39)

Page 35
8.3.3 DTM – IHO Compliance
There are 5 options presented in the IHO layer selection as
shown to the right. The user can request the results to show
how many grid cells meet IHO specifications for chosen order
Special, One or Two), or the user can select ‘All’ to see what
order each grid cell will pass. Selecting the last option ‘Do Not Compute’ will not
generate an IHO compliance layer.
Shown below are the results of the IHO compliance calculation for the 0.5m and 1m grids:
Note the 0.5m grid only passes IHO compliance where there were enough soundings to
calculate a standard deviation. However gridding the data with a 1m grid cell size allows
most of the grid cells to pass IHO Special Order, with only a few grid cells in the wreck
area that did not meet the requirements of IHO Special Order.
The following formula is used for computing IHO compliance:
± √ [a
2
+(b*d)
2
]
where: a = constant depth error, i.e. the sum of all constant errors
b*d = depth dependent error, i.e. the sum of all depth dependent errors
b = factor of depth dependent error
d = depth
0.5m grid 1m grid