Contour Charts

Overview

Contour charts represent three-dimensional data in two dimensions by drawing lines that connect points of equal value (isolines). Like topographic maps showing elevation, contour charts are ideal for visualizing continuous data fields, identifying patterns, and displaying areas of equal value. They can be displayed in 2D or 3D and often complement surface charts. Use cases:

Topographic and terrain mapping
Temperature and weather patterns
Scientific field data visualization
Stress and strain analysis
Density and concentration maps
Mathematical function visualization

Series Class

TContourSeries - The primary class for creating contour charts

Key Properties

Property	Type	Description
`NumLevels`	Integer	Number of contour levels to display
`YPosition`	Double	Y-axis position of contour plane in 3D
`YPositionLevel`	Boolean	Auto-position levels vertically
`ColorEachPoint`	Boolean	Use different colors per level
`AutomaticLevels`	Boolean	Automatically calculate level values
`OnGetLevel`	TContourLevelEvent	Customize individual level values and colors
`Pen`	TPen	Customize contour line appearance
`Marks`	TSeriesMarks	Configure level labels
`Pointer`	TSeriesPointer	Show data points
`SmoothSegments`	Integer	Number of segments for smooth curves

Code Examples

Basic Contour Chart

From VCL/TeeNew/SeriesType_Contour.pas:50:

uses
  TeEngine, TeeSurfa, TeeProcs, Chart, TeeTools;

procedure CreateBasicContour(ContourSeries: TContourSeries; Chart: TChart);
var
  X, Z: Integer;
begin
  // Add XYZ points to the Contour series
  with ContourSeries do
  begin
    Clear;
    for X := -10 to 10 do
      for Z := -10 to 10 do
        AddXYZ(X, CalculateValue(X, Z), Z, '', clTeeColor);
  end;
  
  // Specify how many contour levels
  ContourSeries.NumLevels := 10;
  
  // Set Y position to middle of data range
  with ContourSeries do
    YPosition := (YValues.MaxValue + YValues.MinValue) / 2.0;
  
  // Improve chart appearance
  Chart.Chart3DPercent := 100;
end;

function CalculateValue(X, Z: Integer): Double;
var
  AngleX, AngleZ: Double;
begin
  AngleX := ((X + 10) * 18.0) * Pi / 180.0;
  AngleZ := ((Z + 10) * 18.0) * Pi / 180.0;
  Result := 500.0 * (Sin(AngleX) + Sqr(Cos(AngleZ)));
end;

2D Contour View

From VCL/TeeNew/Contour_View2D.pas (example pattern):

procedure Setup2DContour(Chart: TChart);
begin
  // Switch to 2D view for map-like display
  Chart.View3D := False;
  
  // Optional: Hide walls in 2D
  Chart.View3DWalls := False;
end;

Contour with Surface

From VCL/TeeNew/SeriesType_Contour.pas:78:

procedure CombineContourWithSurface(ContourSeries: TContourSeries; 
  Chart: TChart);
var
  SurfaceSeries: TSurfaceSeries;
begin
  // Create surface series
  SurfaceSeries := TSurfaceSeries.Create(Chart);
  Chart.AddSeries(SurfaceSeries);
  
  // Use contour as data source for surface
  SurfaceSeries.DataSource := ContourSeries;
  
  // Toggle surface visibility as needed
  SurfaceSeries.Active := True;
end;

Custom Contour Levels

From VCL/TeeNew/SeriesType_Contour.pas:92:

procedure SetupCustomLevels(ContourSeries: TContourSeries);
begin
  ContourSeries.NumLevels := 10;
  ContourSeries.OnGetLevel := GetContourLevel;
end;

procedure GetContourLevel(Sender: TContourSeries; LevelIndex: Integer; 
  var Value: Double; var Color: TColor);
begin
  // Specify exact values for each level
  case LevelIndex of
    0: Value := 0;
    1: Value := 100;
    2: Value := 200;
    3: Value := 300;
    4: Value := 400;
    5: Value := 500;
    6: Value := 600;
    7: Value := 700;
    8: Value := 800;
    9: Value := 900;
  else
    Value := LevelIndex * 100;
  end;
  
  // Optional: Specify custom colors for specific levels
  if Value = 500 then
    Color := clRed;
end;

Filled Contours

From VCL/TeeNew/Series_ContourFilled.pas (example pattern):

procedure CreateFilledContour(ContourSeries: TContourSeries);
begin
  // Enable filled regions between contour lines
  ContourSeries.YPositionLevel := False;
  
  // Use color for each level
  ContourSeries.ColorEachPoint := True;
  
  // Use palette for automatic coloring
  ContourSeries.UseColorRange := False;
  ContourSeries.UsePalette := True;
  ContourSeries.PaletteStyle := psRainbow;
end;

Contour Level Marks

From VCL/TeeNew/Series_ContourLevelMarks.pas (example pattern):

procedure ShowLevelMarks(ContourSeries: TContourSeries);
begin
  // Display marks on contour lines
  with ContourSeries.Marks do
  begin
    Visible := True;
    Style := smsValue;  // Show level values
    BackColor := clYellow;
    Transparent := False;
    
    // Prevent overlap
    DrawEvery := 3;  // Draw every 3rd mark
  end;
end;

Contour with Pointers

From VCL/TeeNew/Series_ContourPointer.pas (example pattern):

procedure ShowDataPoints(ContourSeries: TContourSeries);
begin
  // Show original data points
  with ContourSeries.Pointer do
  begin
    Visible := True;
    Style := psCircle;
    HorizSize := 3;
    VertSize := 3;
    Pen.Color := clBlack;
    Brush.Color := clWhite;
  end;
end;

Customization Options

Contour Line Appearance

with ContourSeries.Pen do
begin
  Visible := True;
  Width := 2;
  Color := clBlack;
  Style := psSolid;  // psDot, psDash, etc.
end;

Color Each Level

From VCL/TeeNew/SeriesType_Contour.pas:87:

procedure ColorLevels(ContourSeries: TContourSeries);
begin
  ContourSeries.ColorEachPoint := True;
  
  // Colors will be assigned automatically based on palette or color range
end;

Y Position Control

From VCL/TeeNew/SeriesType_Contour.pas:128:

procedure SetContourPosition(ContourSeries: TContourSeries; Position: Double);
begin
  // Disable automatic positioning
  ContourSeries.YPositionLevel := False;
  
  // Set specific Y position
  ContourSeries.YPosition := Position;
end;

// Or use scrollbar for interactive positioning
procedure ScrollBarChange(Sender: TObject; ScrollPos: Integer);
begin
  ContourSeries.YPosition := 1000 - ScrollPos;
end;

Smooth Contours

From VCL/TeeNew/Contour_SmoothSegments.pas (example pattern):

procedure SmoothContourLines(ContourSeries: TContourSeries);
begin
  // Increase segments for smoother curves
  ContourSeries.SmoothSegments := 20;  // Default is 4
end;

Contour Palette

From VCL/TeeNew/Contour_Palette.pas (example pattern):

procedure SetContourPalette(ContourSeries: TContourSeries; Style: Integer);
begin
  ContourSeries.UsePalette := True;
  
  case Style of
    0: ContourSeries.PaletteStyle := psPale;
    1: ContourSeries.PaletteStyle := psStrong;
    2: ContourSeries.PaletteStyle := psGrayscale;
    3: ContourSeries.PaletteStyle := psRainbow;
    4: ContourSeries.PaletteStyle := psInvGray;
  end;
end;

Advanced Features

From VCL/TeeNew/Contour_Foot.pas (example pattern):

procedure AddContourLegend(Chart: TChart; ContourSeries: TContourSeries);
begin
  // Use chart footer to show level scale
  Chart.Foot.Visible := True;
  Chart.Foot.Text.Text := 'Contour Levels: ' + 
    FloatToStr(ContourSeries.YValues.MinValue) + ' to ' +
    FloatToStr(ContourSeries.YValues.MaxValue);
end;

OnBeforeDraw Event

From VCL/TeeNew/Contour_OnBeforeDraw.pas (example pattern):

procedure SetupBeforeDrawEvent(ContourSeries: TContourSeries);
begin
  ContourSeries.OnBeforeDrawValues := BeforeDrawContour;
end;

procedure BeforeDrawContour(Sender: TObject);
begin
  // Custom drawing code before contours are drawn
  // Useful for background effects or custom rendering
end;

Interactive Level Adjustment

procedure AdjustLevels(ContourSeries: TContourSeries; NewLevels: Integer);
begin
  ContourSeries.NumLevels := NewLevels;
  
  // Recalculate automatic levels
  ContourSeries.AutomaticLevels := True;
end;

Rotate Contour in 3D

uses
  TeeTools;

procedure EnableContourRotation(Chart: TChart);
var
  RotateTool: TRotateTool;
begin
  Chart.View3D := True;
  
  RotateTool := TRotateTool.Create(Chart);
  Chart.Tools.Add(RotateTool);
end;

Export Contour Levels

procedure ExportContourLevels(ContourSeries: TContourSeries; FileName: String);
var
  i: Integer;
  Data: TStringList;
  Value: Double;
  Color: TColor;
begin
  Data := TStringList.Create;
  try
    Data.Add('Level,Value,Color');
    
    for i := 0 to ContourSeries.NumLevels - 1 do
    begin
      Value := 0;
      Color := clNone;
      
      // Get level info
      if Assigned(ContourSeries.OnGetLevel) then
        ContourSeries.OnGetLevel(ContourSeries, i, Value, Color);
      
      Data.Add(Format('%d,%.2f,%s', [i, Value, ColorToString(Color)]));
    end;
    
    Data.SaveToFile(FileName);
  finally
    Data.Free;
  end;
end;

Highlight Specific Level

procedure HighlightLevel(ContourSeries: TContourSeries; TargetLevel: Integer);
begin
  ContourSeries.OnGetLevel := 
    procedure(Sender: TContourSeries; LevelIndex: Integer; 
              var Value: Double; var Color: TColor)
    begin
      if LevelIndex = TargetLevel then
      begin
        // Make this level stand out
        Color := clRed;
        // Width would need custom drawing
      end;
    end;
end;

Contour from Grid Data

procedure LoadGridData(ContourSeries: TContourSeries; GridData: array of array of Double);
var
  X, Z: Integer;
begin
  ContourSeries.Clear;
  
  for X := Low(GridData) to High(GridData) do
    for Z := Low(GridData[X]) to High(GridData[X]) do
      ContourSeries.AddXYZ(X, GridData[X][Z], Z);
  
  ContourSeries.NumLevels := 10;
end;

Polar Contour

From VCL/PolarContour/UPolarContour.pas (example pattern):

uses
  TeePolar;

procedure CreatePolarContour;
var
  PolarSeries: TPolarSeries;
  ContourSeries: TContourSeries;
begin
  // Contour in polar coordinates
  PolarSeries := TPolarSeries.Create(Chart1);
  ContourSeries := TContourSeries.Create(Chart1);
  
  Chart1.AddSeries(PolarSeries);
  Chart1.AddSeries(ContourSeries);
  
  // Configure for polar display
  // ... (requires polar coordinate transformation)
end;

Best Practices

Choose appropriate number of levels - Too few miss detail, too many create clutter (8-12 typically)
Use 2D for clarity - 2D view is often clearer for contour interpretation
Color code thoughtfully - Rainbow for progression, grayscale for technical
Label key levels - Don’t label every contour line
Provide scale reference - Include legend or footer with value range
Combine with surface - Show both contour and surface for complete picture

Surface Charts - 3D representation of the same data
Heat Maps - Color-coded intensity without contour lines
Isometric Charts - Alternative 3D visualization
Polar Charts - Contours in polar coordinates

Get Started

VCL Samples

FMX Samples

Chart Types

Features

Advanced

Overview

Series Class

Key Properties

Code Examples

Basic Contour Chart

2D Contour View

Contour with Surface

Custom Contour Levels

Filled Contours

Contour Level Marks

Contour with Pointers

Customization Options

Contour Line Appearance

Color Each Level

Y Position Control

Smooth Contours

Contour Palette

Advanced Features

Contour with Footer/Legend

OnBeforeDraw Event

Interactive Level Adjustment

Rotate Contour in 3D

Export Contour Levels

Highlight Specific Level

Contour from Grid Data

Polar Contour

Best Practices

Build docs developers (and LLMs) love

Get Started

VCL Samples

FMX Samples

Chart Types

Features

Advanced

​Overview

​Series Class

​Key Properties

​Code Examples

​Basic Contour Chart

​2D Contour View

​Contour with Surface

​Custom Contour Levels

​Filled Contours

​Contour Level Marks

​Contour with Pointers

​Customization Options

​Contour Line Appearance

​Color Each Level

​Y Position Control

​Smooth Contours

​Contour Palette

​Advanced Features

​Contour with Footer/Legend

​OnBeforeDraw Event

​Interactive Level Adjustment

​Rotate Contour in 3D

​Export Contour Levels

​Highlight Specific Level

​Contour from Grid Data

​Polar Contour

​Best Practices

​Related Chart Types

Build docs developers (and LLMs) love

Overview

Series Class

Key Properties

Code Examples

Basic Contour Chart

2D Contour View

Contour with Surface

Custom Contour Levels

Filled Contours

Contour Level Marks

Contour with Pointers

Customization Options

Contour Line Appearance

Color Each Level

Y Position Control

Smooth Contours

Contour Palette

Advanced Features

Contour with Footer/Legend

OnBeforeDraw Event

Interactive Level Adjustment

Rotate Contour in 3D

Export Contour Levels

Highlight Specific Level

Contour from Grid Data

Polar Contour

Best Practices

Related Chart Types