See Also
Functional Description of the Contour Options
The previous help topics discussed basic contour options in the order they are arranged on the dialog. The dialog is arranged so that the most important options are on the first tab and other on the Contour Type Options tab. This help topic discusses the options in a manner which better describes how the contour is actually created. A contour is calculated generally by a five-step process
- Build a list of all possible data points (graphical locations)
- Remove items that meet criteria from the list of data points
- Assign a value to each data point
- Calculate "virtual values" on a grid of points
- Convert each "virtual values" into a color to create the contour image
Step 1: Build a list of data points (graphical locations)
The following options determine a list of potential data points (could also be called graphical locations) which will be used to calculate the contour image.
Object - Simulator can contour several different values. To specify what Simulator should contour, first choose the type of object. This corresponds to the type of display object that is drawn on the oneline diagram. For instance if you want to contour a substation value, then you must have substations drawn on your diagram. This selection narrows the set of quantities that can be contoured, which is specified in the Value dropdown box.
Data points Per Line - The contouring algorithm for lines is no different than for points, except that each line is represented by several points. For objects which are represented by graphical lines, this option will specify the number of data point which should be used to represent the line.
Step 2: Remove items that meet criteria from the list of data points
After a complete list of potential data points is made, there are then several options for filtering out things from this list which you do not want to effect the calculation of the contour image.
Filter - If you wish for the contour to be limited to only certain devices that meet specific criteria, click on this button to define an Advanced Filter for the contour
Ignore Above Max - Check this check-box to completely ignore values above the maximum percentage. This means that data which is larger than the Max % will not be used in calculating the contour image
Ignore Above Min - Check this check-box to completely ignore values below the minimum percentage. This means that data which is smaller than the Min % will not be used in calculating the contour image
Ignore Zero Values - Check this check-box to completely ignore values that are zero.
Step 3: Assign a value to each data point
After Step 2, a list of potential data points has been created and a value must now be assigned to each data point. The following options specify how this is done.
Value - select the quantity to contour from the Value dropdown box or click the Find Value button to find the desired field.
Use absolute value - This check-box will modify the Value specified so that it uses the absolute value.
Interpretation – When interpretation is set to either Standard Deviations or Percentiles, then the value of the data point will be modified.
If Standard Deviations is chosen, then all the data point values will be used to determine a mean and standard deviation. The data point values will then be converted to represent the number of standard deviations they are from the mean. Thus a value equal to the mean will be changed to a 0, a value 1.5 standard deviations higher than the mean will be changed to 1.5, and so on. Similar,
If Percentiles is chosen, then all the data point values will be sorted from lowest to highest. The value will then be set equal to the 100 times the sort location divided by the number of data points. Thus the highest value will be given a value of 100 and the lowest a value of 1.
Step 4. Calculate "virtual values" on a grid of points
After Step 3, we now have a list of data points and a value assigned to each data point. We now must create a grid of points that represents "virtual values" throughout the entire graphical space. The values on this grid will be calculated based on the data point values
Contour Resolution - setting determine the size of the grid of points which will be superimposed on the present oneline diagram. The higher the resolution the more number of grid points will be used to represent the contour (and thus make the calculation of the contour image slower)
Influence Region - each data point value will effect only the grid locations that are "near" it. The distance that is considered "near" is determined by the Influence Region. Setting the influence region higher will result in each data point effecting a larger portion of the contour image (and thus making the calculation of the contour image slower)
Kind of Value - The calculation of the virtual value at a particular grid point is done by first building a list of data points that are within the "influence distance" of the grid point. The Kind of Value setting determines what process is used to calculate the virtual value from this list of values.
Actual Value (Weighted Average) - The virtual value is calculated as the weighted average value, weighted by the distance from the grid point. This means that virtual value half-way between two data points will be the average of the two data point values.
Density of Values (Weighted Sum) - The virtual value is calculated as the sum of value that within the influence region. This means that virtual value half-way between two data points will be the sum of the two data point values.
Actual Value (Only Closest) - The virtual value is assigned as the value of the closest data point.
Fade to Value and Begin Fade Percentage - In the middle of a contour image the colors look consistent because the virtual values are calculated using a good number of data points which surround it. Sometimes at the edge of a contour image however, the colors can become skewed because there are very few data points influencing it. Using a fade to value can help this situation, but will skew the entire contour image in general instead. Without using the fade to value, the raw data point values will be used when calculating virtual value.
When using the fade to value, while moving away from a data point, the data point’s value decays towards the "Fade to" Value. The Begin Fade Percentage specifies when the contour starts to fade as a percentage of the largest distance for which this data point influences the contour.
Step 5. Convert each "virtual values" into a color to create the contour image
After Step 4, a grid of virtual values has been calculated. At this point, must specify how these numbers map to colors. This done through the user of a Color Map.
Color Map - Choose from various predefined color maps using the color map combo-box. A color map, along with the values specified, defines how values are mapped to a color on the contour image. A user may also define additional color maps by going to the Custom Color Map Tab.
Brightness - this value is used to brighten or darken the colors specified in the color map.
Values - These values along with the color map define how to convert your values into a color for the contour. The values are:
Maximum - The largest value allowed in the contour. All values above this will be mapped to the highest color. This value corresponds to 100% in the color map.
Break High - This value is used by some color maps to highlight a lower limit. This value corresponds to 75% in the color map.
Nominal - This value is the nominal value for the contour. Values around this will be mapped to the middle color. This value corresponds to 50% in the color map.
Break Low - This value is used by some color maps to highlight a lower limit. This value corresponds to 25% in the color map.
Minimum - The smallest value allowed in the contour. All values below this will be mapped to the lowest color. This value corresponds to 0% in the color map.
Interpretation - Most frequently this option will be set to Fixed Values meaning values for maximum, break high, etc… are entered directly in the units of the value being contoured. If Interpretation is set to Standard Deviations or Percentiles then as mentioned earlier the values mean something different. The options Dynamic Values will process this list of data point values and automatically set the values as follows: Maximum = Maximum data point value; Minimum = Minimum data point value; Nominal = Average data point value; Break High = (Max + Average)/2; and Break Low = (Min + Average)/2.
No Data Color - It is likely that some the grid points will not be within the influence of any of the data points. The color of these points is determined by no data color setting.