ArcGIS Help 10.1 - Scale Minimum: Fixed Value method (Maritime Charting)

The Fixed Value method calculates the SCAMIN value for S-57 features based on a calculation type and a designated value for each rule in the XML file.

Consider the following when configuring rules in the SCAMIN.xml file:

Calculation types
Syntax for calculation types
Order of precedence
Chart scale and syntax
M_CSCL features
An XML rule set for each navigation purpose is recommended

Calculation types

Type name	Abbreviation in .xml file	Calculation type description
Absolute	A	Sets a fixed SCAMIN value for each feature in the specified feature class and subtype.
Factor	F	Sets the SCAMIN value to the product of multiplying the compilation scale of the S-57 cell* and a number established in the XML for the specified feature class and subtype (*see the M_CSCL features section in this topic).
Structure	S	Evaluates each feature for a specified feature class and subtype to see if it is a slave participating in a master/slave relationship. If it qualifies, the SCAMIN value is set equal to the SCAMIN of the master feature. If the feature does not qualify as a slave, it receives the fixed value defined in the SCAMIN rule.

Calculation types

You can use attribute combinations with the Factor and Absolute calculation types to further refine the SCAMIN rule to the attribute level. Attribute combinations set the SCAMIN value for a specified feature class and subtype based on one or more qualifying attributes. Features that have the appropriate attribute(s) receive the SCAMIN value defined in the rule.

Attribute combinations can't be used with the Structure calculation type.

When you enter multiple values, a feature must match all attributes to qualify for that rule.

Example:

<Attributes> 
<Attribute field="BUISHP" value="5"/> 
<Attribute field="NATCON" value="6,9"/> 
</Attributes>

To qualify for this SCAMIN value, the feature must have BUISHP = 5 and NATCON =6 and NATCON =9. Certain attribute types, like list fields, can have additional values. For example, NATCON = "4,9,6,3", but 6 and 9 must be present to qualify for the rule. If NATCON = "4,9,3", the feature doesn't qualify because it doesn't have attribute value 6. All attribute values defined in the SCAMIN rule must be present on the feature for the SCAMIN value to be set.

Syntax for calculation types

The following is the rule syntax for the SCAMIN.XML:

<Object FeatureClass ="InputFeatureClassHere" SubType="InputSubtypeHere">
      <CalculationType type="InputCalculationTypeHere"/>
      <SCAMIN value="InputSCAMINValue or MultiplicationFactor"/>
</Object>

The following are examples of syntax for different calculation types:

Absolute calculation<Object FeatureClass ="CulturalFeaturesA" SubType="BUISGL_BuildingSingle">
      <CalculationType type="A"/>
      <SCAMIN value="100000"/>
</Object>

Absolute calculation with an attribute combination<Object FeatureClass ="CulturalFeaturesA" SubType="BUISGL_BuildingSingle">
     <Attributes>
     <Attribute field="BUISHP" value="5"/>
     <Attribute field="NATCON" value="6,9"/> 
     </Attributes>         
     <CalculationType type="A"/>
     <SCAMIN value="55555"/>
</Object>

Factor calculation<Object FeatureClass ="DangersP" SubType="OBSTRN_Obstruction">
      <CalculationType type="F"/>
      <SCAMIN value="2"/>
</Object>

Structure calculation<Object FeatureClass ="AidsToNavigationP" SubType="DAYMAR_Daymark"> 
      <CalculationType type="S"/>
      <SCAMIN value="90000"/>
</Object>

Order of precedence

When establishing the Fixed Value method rules within the SCAMIN.xml file, you must keep in mind that there is an order of precedence. Currently, the tool reads the parameters from the Fixed Value method SCAMIN XML in a top-to-bottom manner. If care is not taken to stage the rules correctly, a more detailed rule could be overwritten by a more general rule. Please follow these guidelines to ensure that the SCAMIN values are assigned accurately. The calculations should be defined in the following order:

List the absolute calculations prior to all other calculation types.
List factor calculations next. (You can list them first if no single feature class/subtype is listed twice. If so, the last rule will be used to determine SCAMIN.)
List attribute combination type calculations next from simple to more complex if more than one type of combination is used for a single feature class/subtype.
For example, a rule that evaluates buildings (BUISGL), such as a church (FUNCTN=20), should precede a rule that evaluates a church (FUNCTN=20) that is visually conspicuous (CONVIS=1). The tool processes the XML from top to bottom, with the last action overriding all the others, so revising the order would mean that all churches would be set to the same SCAMIN value, even those that are visually conspicuous.
List structure calculations last, as they are dependent on the fact that all potential master features must be processed first. In addition, according to S-57 Appendix B.1 - Annex A, "When the nature of the base structure is unknown or there is no structure object, one of the equipment objects must be chosen as the master object, giving priority to a LIGHTS object, if one exists." LIGHTS features should be processed prior to all other structure calculations.

Chart scale and syntax

One of the limitations of configuring a single Fixed Value method SCAMIN XML file is that many features may have their SCAMIN set to a value that does not meet the following requirement:

"Where SCAMIN is used, it must always be set to a scale less (i.e., to a smaller scale) [See note] than or equal to the compilation scale of the data as described in clause 2.2.6 [. . .]. Failure to follow this rule will mean that objects will not be displayed on screen until the over-scale warning is activated."

To overcome this limitation, the SCAMIN tool evaluates each feature to see if the SCAMIN value is set to a scale less than the compilation scale of the data (including those that fall within an M_CSCL feature). If a feature is found to be at a larger scale or equal to the S-57 cell or, when applicable, the M_CSCL feature, then the value is set to the next smaller scale listed in the ChartScale portion of the SCAMIN.xml file. If the compilation scale of the S-57 cell (M_CSCL) is not equal to one defined in the .xml file, the next smaller scale is used to determine the SCAMIN value.

Example: The ENC compilation scale is 12000. A feature has a SCAMIN of 9000. This feature fails to meet the requirement that it must be less than the scale of the ENC. Since the ENC compilation scale 12000 is not listed in the example syntax below, 25000 is the next smaller scale available for the SCAMIN value.

Example of the syntax

<ChartScale>
    <CompilationScale value ="250000"/>
    <CompilationScale value ="100000"/>
    <CompilationScale value ="75000"/>
    <CompilationScale value ="50000"/>
    <CompilationScale value ="25000"/>
    <CompilationScale value ="10000"/>
</ChartScale>

Tip:

This may be counterintuitive. Scale is a ratio, so the larger the number, the further the feature is from the actual size; hence, smaller scale.

M_CSCL features

M_CSCL features are used to indicate that a subset of features within the S-57 cell has a different compilation scale than the main portion of the dataset. Features spatially within these areas are evaluated based on the M_CSCL compilation scale.

The existence of an M_CSCL meta object impacts the behavior of the ArcGIS for Maritime: Charting SCAMIN tool. Features that are configured to use the Fixed Value method of factor calculation replace the main ENC compilation scale with the one provided by the M_CSCL feature. In addition, the chart scale used to determine whether features of a smaller scale takes the compilation scale from the Meta object. To support this, all features should be split along M_CSCL boundaries; those that are not are flagged in the SCAMIN log file.

The SCAMIN lock

The SCAMIN_LOCK attribute is a Boolean field at the feature level used to override the SCAMIN process.

SCAMIN_LOCK	Description
LOCKED	By setting the SCAMIN_LOCK equal to (1), the SCAMIN process will preserve the current SCAMIN attribute value on the feature and ignore settings in the selected SCAMIN.xml file.
UNLOCKED or Null	By setting the SCAMIN_LOCK equal to (0) or <Null>, the feature will be processed, and the SCAMIN will be set according to the selected SCAMIN.xml configuration.

SCAMIN Lock

Reviewing the SCAMIN log file

After the SCAMIN tool is run, you can review the SCAMIN log file. This file contains records of which features were modified and reports any issues the SCAMIN tool encountered.

Example: When a feature is not split as it crosses the main ENC cell into a MetaDataA (M_CSCL) feature or if a feature falls exactly on the MetaDataA boundary, then the feature is written to the log file.

The location of the log files generated by the tool is different depending on your operating system:

On Windows XP, log files are written to <Installation location>\Documents and Settings\<User Login>\Application Data\ESRI\Production10.1\Nautical\LogFiles\SCAMIN.
On Windows Vista, Windows 7, and Windows Server 2008, log files are written to <Installation location>\Users\<UserLogin>\AppData\Roaming\ESRI\Production10.1\NAUTICAL\LogFiles\SCAMIN.

If the location doesn't exist, the tool creates the directory for it. The log file is saved in XML format.

The name of the log file will be SCAMIN_<product name>_YYYYMMDDTHHMMSS.log. The log file will contain the following information:

What cell it ran on
The date and time it was run
SCAMIN method that was run, "Fixed Value" or "Radar Range" indicated by the "Method" tag in the header information
What features were modified
The NOID of features modified
The original SCAMIN value
The updated SCAMIN value
How long it took in HHMMSS

Example log entry:

Tool Name: SCAMIN 
Time: 11/19/2010 9:11:31 AM
Cell Name: US5MD14M 
Method: Fixed Value
  
Feature Class Name: SoundingsP 
Subtype: SOUNDG_Soundings
NOID: {00039A53-B97F-4A0B-84C1-1FB67FA56B27}
Original SCAMIN value: 79999
Updated SCAMIN value: 80000

SCAMIN ran successfully.

Time Interval: 3 Hrs 3 Mins 49 Secs

12/22/2014