Nevron .NET Vision Documentation
Triangulated Heat Map

The triangulated heat map is a type of chart which represents a set of points with three values (X, Y and Z) as a heat map. The input set is used to build a triangulation map which can be filled using a specified palette. The following images show a triangulated heat map:

 

Creating a Triangulated Heat Map

You create a triangulated heat map series by creating an instance of the NTriangulatedHeatMapSeries class and then adding it to the series collection of the chart. The following code shows how to create a triangulated heat map series and add it to the chart:

C#
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// get the cartesian chart created by default
NChart chart = nChartControl1.Charts[0];

// create a triangulated heat map series
NTriangulatedHeatMapSeries heatMap = new NTriangulatedHeatMapSeries();

chart.Series.Add(heatMap);

Visual Basic
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' get the cartesian chart created by default
Dim chart As NChart = NChartControl1.Charts(0)

' create a triangulated heat map series
Dim heatMap As New NTriangulatedHeatMapSeries()

chart.Series.Add(heatMap)

Adding Data
       

Once the Triangulated Heat Map series is created you can add some data in it. Triangulated Heat Map series use the Values data series for y (elevation) values, the XValues data series - for x position values and the YValues data series for y position values. You should add at least three distinct points in order to display a heatmap.

C#
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// add some dummy data (pyramid in this case)
heatMap.Values.Add(0);
heatMap.XValues.Add(0);
heatMap.YValues.Add(0);

heatMap.Values.Add(0);
heatMap.XValues.Add(1);
heatMap.YValues.Add(0);

heatMap.Values.Add(0);
heatMap.XValues.Add(1);
heatMap.YValues.Add(1);

heatMap.Values.Add(0);
heatMap.XValues.Add(0);
heatMap.YValues.Add(1);

heatMap.Values.Add(1);
heatMap.XValues.Add(0.5);
heatMap.YValues.Add(0.5);

Visual Basic
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' add some dummy data (pyramid in this case)
heatMap.Values.Add(0)
heatMap.XValues.Add(0)
heatMap.YValues.Add(0)

heatMap.Values.Add(0)
heatMap.XValues.Add(1)
heatMap.YValues.Add(0)

heatMap.Values.Add(0)
heatMap.XValues.Add(1)
heatMap.YValues.Add(1)

heatMap.Values.Add(0)
heatMap.XValues.Add(0)
heatMap.YValues.Add(1)

heatMap.Values.Add(1)
heatMap.XValues.Add(0.5)
heatMap.YValues.Add(0.5)

Heat Map Palette

The color assigned to each heat map vertex (xyz point ) is computed using the palette assigned to the triangulated heat map series, which is accessible from the Palette property. The following code shows how to create a simple custom palette which maps the values from 0 to 10 to shades of gray, where 0 is mapped to black and 10 to white:

C#
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heatMap.Palette.Mode = PaletteMode.Custom;

heatMap.Palette.Clear();

heatMap.Palette.SmoothPalette = true;

heatMap.Palette.Add(0, Color.Black);

heatMap.Palette.Add(10, Color.White);

Visual Basic
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heatMap.Palette.Mode = PaletteMode.Custom

heatMap.Palette.Clear()

heatMap.Palette.SmoothPalette = True

heatMap.Palette.Add(0, Color.Black)

heatMap.Palette.Add(10, Color.White)

The double.NaN value is always mapped to transparent color. This allows you to define holes or missing values in the heat map grid.
Contour Lines

The triangulated heat map series has the ability to show contour lines. In order to show contour lines for different value levels you need to first assign a proper palette - usually this is a palette in custom mode like in the above code examples.

Then you need to enable contour lines using the ContourDisplayMode property:

C#
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heatMapSeries.ContourDisplayMode = ContourDisplayMode.Contour;

Visual Basic
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heatMapSeries.ContourDisplayMode = ContourDisplayMode.Contour

The following table shows the available options:

ContourDisplayMode Description
None Contour lines are not shown. This is the default.
Contour Displays the connected contours.
Dots Displays the contour points as dots. The dot size is controlled from the ContourDotSize property.

When contour lines are visible you can also control their stroke and color. This is achieved from the ContourStroke and ContourColorMode properties. The latter accepts values from the ENContourColorMode enum:

ENContourColorMode Description
Uniform The contours are displayed with stroke style taken from the ControurStrokeStyle property.
Palette The contours are displayed with stroke taken from the ControurStroke property and color taken from the associated palette for the controur level.

 

Contour Labels

The triangulated heat map series can display labels at the contour lines that show their value. The contour labels functionality is controlled from the ContourLabelStyle property of the control. The following code shows how to enable contour labels:

C#
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heatMap.ContourLabelStyle.Visible = true;
Visual Basic
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heatMap.ContourLabelStyle.Visible = True

In addition you can modify other parameters of the controur labels such as whether they should clip the contour, whether to allow flipping, their formatting and others. The following code snippet shows how to modify several commonly used contour label properties:

C#
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heatMap.ContourLabelStyle.Visible = true;
heatMap.ContourLabelStyle.AllowLabelToFlip = false;
heatMap.ContourLabelStyle.LabelDistance = new NLength(50);
heatMap.ContourLabelStyle.Format = "<value>";
heatMap.ContourLabelStyle.TextStyle.FillStyle = new NColorFillStyle(Color.Red);

Visual Basic
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heatMap.ContourLabelStyle.Visible = True
heatMap.ContourLabelStyle.AllowLabelToFlip = False
heatMap.ContourLabelStyle.LabelDistance = New NLength(50)
heatMap.ContourLabelStyle.Format = "<value>"
heatMap.ContourLabelStyle.TextStyle.FillStyle = New NColorFillStyle(Color.Red)
Heat Map Legend

As with all series the heat map has an associated legend. It provides special treatment for the SeriesLegendMode.SeriesLogic legend mode. When set in this mode the heat map can display information about the coloring in table or gradient axis legend mode. For example:

C#
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heatMap.Legend.Mode = SeriesLegendMode.SeriesLogic;

heatMap.Legend.PaletteLegendMode = PaletteLegendMode.GradientAxis;

heatMap.Legend.PaletteScaleStepMode = PaletteScaleStepMode.SynchronizeWithScaleConfigurator;

Visual Basic
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heatMap.Legend.Mode = SeriesLegendMode.SeriesLogic;

heatMap.Legend.PaletteLegendMode = PaletteLegendMode.GradientAxis;

heatMap.Legend.PaletteScaleStepMode = PaletteScaleStepMode.SynchronizeWithScaleConfigurator;

Related Examples

Windows forms: Chart Gallery\Triangulated Heat Map\

Wpf: Chart Gallery\Triangulated Heat Map\

Web Forms: Chart Gallery\Triangulated Heat Map\

 

See Also

 

 


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