Log Map Controller

The Log Map Controller is used to configure aspects of Log Mapping and auto mapping.  This view may be added from all the usual places - see Adding an Object, and is found under the following sub menu: Add Log Map Controller...

If you are trying to auto-map using a Lambda Log Map, you will typically want a negative feedback loop.  To configure this, set the Multiplier value to a negative number (e.g. -1).

The Log Map Controller is divided into sections:

Auto mapping

This section gives the user some feedback about the internal state of the log-mapping algorithm and can be useful for discovering reasons why auto mapping might not be working appropriately.

• Capturing is a percentage of the algorithm’s current logged weight compared to the weight before change. Once this reaches 100%, the algorithm will change the current cell’s value.

• Target Error is the current difference between the base map and target map.

• Map Adjustment shows the current expected change to the base map that the algorithm will make in real and percentage terms.

Targeting

Gives control over site filtering based on target accuracy and weight.

• Target Accuracy - This value defines how different the logged channel value should be from the target map value before it is considered for auto mapping.

• Weight Before Change - This defines the value that Confidence should reach before a site is considered for auto mapping. It has units of milliseconds.

Modifications

Gives control over how the Log Map modifies its base map when auto mapping.

• Modify Base Map By - Defines how the logged channel difference is used to adjust the base map by when auto mapping. This can either be:

  • Percentage: The channel difference value from the target map modifies the base map site value by a percentage of its current value. If using this mode, you can only perform auto mapping on non-zero base map cells.
  • Additive: The channel difference is added to the current map site value.

• Multiplier - The channel difference value is multiplied by this value.  For a negative feedback loop (common with Lambda), use a negative value here.

• Offset - This value is added to the channel difference after the multiplier has been applied.

Limit Changes to Map

Allows you to define the maximum amount that auto mapping may modify the base map by. The maximum change is defined for each direction, so subtractions from the base map value can have a different limit to additions.

These two changes are denoted by the ‘+’ and ‘-’ boxes. Max Absolute Change Is the maximum difference that can be applied to the base map as an offset from the original site value.

Max Percent Change Is the maximum percentage difference that may be applied to a map site. This is based on the original map value multiplied by the percentages given in the boxes.

Restart Capturing

Click this button to reset the weight of the currently selected cell(s).  This can be useful if the system has not yet reached stability and you want to restart the weight calculations for the current site(s).

Apply One Adjustment

Clicking this button will calculate and adjust the a single selected site according to the current weight. The weight will then be reset to zero.

Start Auto Mapping

Once you are happy with the Log Map Controller settings, click the ‘Start Auto Mapping’ button. GWv4 will then begin to auto map the base map to the target map.

View Properties

Properties editable via the properties editor.