CARIS BASE Editor : S-57 Composer and S-100 : S-57 Composer and S-100 Support Files : Scale Minimum Values : Soundings : Step Method
 
Step Method

The step method for applying SCAMIN uses step values from the S-65 standard for ENC consistency. A SCAMIN value is assigned to each sounding, based on step values.

The step method uses these files: scalesSCAMIN.xml and sdgparm_IHO.txt, located in:

C:\Program Files\CARIS\<application>\<version>\modules\S‑57 Composer\support

If necessary, they can be modified to meet your requirements.

scalesSCAMIN.xml contains a list of SCAMIN values:

<SCAMIN>

   <SCAMINValue>19999999</SCAMINValue>

   <SCAMINValue>9999999</SCAMINValue>

   <SCAMINValue>4999999</SCAMINValue>

   <SCAMINValue>2999999</SCAMINValue>

   <SCAMINValue>1499999</SCAMINValue>

  <SCAMINValue>699999</SCAMINValue>

   <SCAMINValue>499999</SCAMINValue>

   <SCAMINValue>349999</SCAMINValue>

   <SCAMINValue>259999</SCAMINValue>

   <SCAMINValue>179999</SCAMINValue>

   <SCAMINValue>119999</SCAMINValue>

  <SCAMINValue>89999</SCAMINValue> 

   <SCAMINValue>59999</SCAMINValue>

   <SCAMINValue>44999</SCAMINValue>

   <SCAMINValue>29999</SCAMINValue>

   <SCAMINValue>21999</SCAMINValue>

   <SCAMINValue>17999</SCAMINValue>

   <SCAMINValue>11999</SCAMINValue>

   <SCAMINValue>7999</SCAMINValue>

   <SCAMINValue>3999</SCAMINValue>

   <SCAMINValue>1999</SCAMINValue>

   <SCAMINValue>999</SCAMINValue>

</SCAMIN>

The step values are derived from sdgparm_IHO.txt:

Table Number  Minimum Depth  Maximum Depth  Radius (sounding suppression)

              (meters)        (meters)        (mm at map scale)

 

  1            -15                5            30

  1              5               30            40

  1             30             9999            50

 

  2            -15                5            20

  2              5               30            30

  2             30             9999            40

 

  3            -15                5            15

  3              5               30            20

  3             30             9999            30

 

  4            -15                5            10

  4              5               30            15

  4             30             9999            20

 

SECTION 2:

 

Table Number  Step Number

 

  1                4

  2                3

  3                2

  4                1

default            1

The step method uses sounding suppression values in sdgparm_S65.txt to determine a table value that is used to determine a step number.

For each depth range, the shallowest sounding within the sounding suppression radius is selected to get a table number that is then used to apply a step number and a SCAMIN value.

In this example, Assign SCAMIN is run on a sounding with a Z value of 25.0 metres in a chart with a scale of 5000.

On the first pass, if that sounding is the shallowest within a suppression radius of 40 metres, a table value 1 is used to assign it a step number of 4. The step number is then used to determine a SCAMIN value from ScaleSCAMIN.xml.

The next higher scale value in ScaleSCAMIN.xml is located and this is used as a starting point for applying the step number. In this case, the closest scale value to 5000 is 7999. A step value of four is used to count up to arrive at a final SCAMIN value of 21999 for the sounding.