CARIS HPD : HPD® User Guide : Vector Product : Scale Minimum : Soundings : Step Method
 
Step Method

The step method for applying scale minimum values uses step values from the S-57 UOC standard for ENC consistency. Product Editor assigns a scale minimum value to each sounding based on step values.

The step method uses two files: scalesSCAMIN.xml and sdgparm_IHO.txt, in ...\CARIS\HPD\<version>\system. Both can be modified if necessary.

scalesSCAMIN.xml contains a list of scale minimum values:

<SCAMIN>

   <SCAMINValue>19999999</SCAMINValue>

   <SCAMINValue>9999999</SCAMINValue>

   <SCAMINValue>4999999</SCAMINValue>

   <SCAMINValue>2999999</SCAMINValue>

   <SCAMINValue>1499999</SCAMINValue>

   <SCAMINValue>999999</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. For example:

Table Number  Minimum Depth  Maximum Depth  Radius (for 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 to determine a table number that, in turn, determines a step number.

For each depth range, the shallowest sounding within the suppression radius is assigned a scale minimum value.

Example

In this example, a sounding has a Z value of 25 metres and the chart has a compilation scale of 5000. The sounding will always fall into the second range in each group in section 1 in sdgparm_IHO.txt.

The compilation scale of the chart is used to determine step 1 in ScalesSCAMIN.xml. In this example, the value 5000 does not exist in the file, therefore the next highest value is used. In this example, that would be 7999.

In the first pass, the suppression radius is 40mm at map scale.

If the sounding is the shallowest within the suppression radius, the step number is determined from section 2. In this example, that number is 4. The step number is then used to determine a scale minimum value from ScalesSCAMIN.xml. In this example, the scale minimum value is 21999.

If the sounding is not the shallowest, no scale minimum value is assigned. The sounding continues to the second pass, third pass, and fourth pass, if necessary.

Remaining soundings are given a default step number of 1 and therefore a scale minimum value of 7999.