Scale Factor Method

Mapping files

The scale method for non-sounding features has the following special conditions:

• The S-57 UOC standard requires that line and area features that extend beyond the product (cell) extents and into a neighbouring cell of a smaller navigational purpose be assigned the scale minimum values of the smaller navigational-purpose cell.

• The S-57 UOC standard requires that the individual occurrences of a feature across several usages should be set to 1, 2, 3, or 4 steps smaller than the smallest usage.

For the above two points, the HPD scale minimum value methods are applied only to the product that is open. It is not applied to neighbouring charts or charts on other usages. You should examine the scale minimum value requirements of the currently open product against neighbouring or associated charts.

HPD currently ignores scale minimum values for conditions like these:

• The most significant OBSTRN (obstruction) feature in a group of OBSTRN features within close proximity.

• A group of OBSTRN features in close proximity to each other, or within an OBSTRN area (excluding the most significant).

• Isolated installations of OFSPLF (offshore platform) features.

• A SILTNK (silo/tank) feature as a representative of a group of SILTNKS.

The scale factor method for determining scale minimum value for area, line, and point features uses one of the following mapping files:

• assignscamin.xml: ENC and AML products.

• assignEUIENCSCAMIN.xml: European IENC products. Based on the IENC Encoding Guide 1.3.1 for European IENC.

• assignUSIENCSCAMIN.xml. US IENC products. Based on the IENC Encoding Guide 1.3.1 for US IENC.

These files are located in ...\CARIS\HPD\<version>\system.

They follow the structure and syntax of other mapping files. See Support Files for more information.

This is an example of the file:

In the above example, a scale factor of 4 is used to calculate the scale minimum value for the LNDMRK (landmark) feature.

The following formula is used when the scale minimum value is applied:

Scale minimum = (compilation scale/divisor)*scale factor

For the LNDMRK feature, scale minimum value is calculated as (compilation scale/divisor)*4.

The compilation scale is determined from the S-57 product or from a meta-compilation scale area (M_CSCL feature). If a feature falls within a meta-compilation scale area, the compilation scale is taken from the CSCALE attribute of the area. The CSCALE attribute overrides the compilation scale of the product.

If the data set has a scale of 0, scale minimum value is undefined.

The divisor is 1.0 when the compilation scale is derived from a meta-compilation scale area and 2.0 when the compilation scale is derived from the product.

If a feature overlaps more than one meta-compilation scale area, the scale of the first area overlapping the feature is used.

CSCLMultiplier

An alternate method of calculating scale minimum value is to use the CSCLMultiplier. The CSCLMultiplier is a user-defined value that overrides the divisor.

The following formula is used when calculating scale minimum value using CSCLMultiplier.

Scale minimum = (compilation scale * CSCLMultiplier) * scale factor

For example, to calculate scale minimum value using the compilation scale of the product without a divisor, set CSCLMultiplier to 1.0. CSCLMultiplier cannot be used with a scale value from a meta area, such as CSCALE).

The CSCLMultiplier value is not included in assignscamin.xml or any of the product-specific assign scale minimum files. You must manually enter the multiplier into the file. The following example shows the LNDMRK feature with the CSCLMultiplier.

In the above example, CSCLMultiplier is 2 and the scale factor is 4. For the LNDMRK feature, the scale minimum value is calculated as:

Scale minimum = (compilation scale * 2.0) * 4