How to create a raster unique value renderer

Creating a raster unique value renderer

1. Get the raster attribute table and table size.
2. Create colors for each unique value.
3. Create a unique value renderer.
4. Set the renderer properties.
   
   See the following code example:
   

[C#]

public IRasterRenderer UnqueValueRenderer(ESRI.ArcGIS.Geodatabase.IRasterDataset
    rasterDataset)
{
    try
    {
        //Get the raster attribute table and the size of the table.
        IRaster2 raster=(IRaster2)rasterDataset.CreateDefaultRaster();
        ITable rasterTable=raster.AttributeTable;
        if (rasterTable == null)
        {
            return null;
        }
        int tableRows=rasterTable.RowCount(null);
        //Create colors for each unique value.
        IRandomColorRamp colorRamp=new RandomColorRampClass();
        colorRamp.Size=tableRows;
        colorRamp.Seed=100;
        bool createColorRamp;
        colorRamp.CreateRamp(out createColorRamp);
        if (createColorRamp == false)
        {
            return null;
        }
        //Create a unique value renderer.
        IRasterUniqueValueRenderer uvRenderer=new RasterUniqueValueRendererClass();
        IRasterRenderer rasterRenderer=(IRasterRenderer)uvRenderer;
        rasterRenderer.Raster=rasterDataset.CreateDefaultRaster();
        rasterRenderer.Update();
        //Set the renderer properties.
        uvRenderer.HeadingCount=1;
        uvRenderer.set_Heading(0, "All Data Value");
        uvRenderer.set_ClassCount(0, tableRows);
        uvRenderer.Field="Value"; //Or any other field in the table.
        IRow row;
        ISimpleFillSymbol fillSymbol;
        for (int i=0; i < tableRows; i++)
        {
            row=rasterTable.GetRow(i);
            uvRenderer.AddValue(0, i, Convert.ToByte(row.get_Value(1))); 
                // Assuming the raster is 8-bit.
            uvRenderer.set_Label(0, i, Convert.ToString(row.get_Value(1)));
            fillSymbol=new SimpleFillSymbolClass();
            fillSymbol.Color=colorRamp.get_Color(i);
            uvRenderer.set_Symbol(0, i, (ISymbol)fillSymbol);
        }
        return rasterRenderer;
    }
    catch (Exception ex)
    {
        System.Diagnostics.Debug.WriteLine(ex.Message);
        return null;
    }
}

[VB.NET]

Public Function UnqueValueRenderer(ByVal rasterDataset As ESRI.ArcGIS.GeodataMyBase.IRasterDataset) As IRasterRenderer
    Try
    'Get the raster attribute table and the size of the table.
    Dim raster As IRaster2=CType(rasterDataset.CreateDefaultRaster(), IRaster2)
    Dim rasterTable As ITable=raster.AttributeTable
    If rasterTable Is Nothing Then
        Return Nothing
    End If
    Dim tableRows As Integer=rasterTable.RowCount(Nothing)
    
    'Create colors for each unique value.
    Dim colorRamp As IRandomColorRamp=New RandomColorRampClass()
    colorRamp.Size=tableRows
    colorRamp.Seed=100
    Dim createColorRamp As Boolean
    colorRamp.CreateRamp( createColorRamp)
    If createColorRamp=False Then
        Return Nothing
    End If
    
    'Create a unique value renderer.
    Dim uvRenderer As IRasterUniqueValueRenderer=New RasterUniqueValueRendererClass()
    Dim rasterRenderer As IRasterRenderer=CType(uvRenderer, IRasterRenderer)
    rasterRenderer.Raster=rasterDataset.CreateDefaultRaster()
    rasterRenderer.Update()
    
    'Set the renderer properties.
    uvRenderer.HeadingCount=1
    uvRenderer.set_Heading(0, "All Data Value")
    uvRenderer.set_ClassCount(0, tableRows)
    uvRenderer.Field="Value" 'Or any other field in the table.
    Dim row As IRow
    Dim fillSymbol As ISimpleFillSymbol
    Dim i As Integer
    For i=0 To tableRows - 1 Step i + 1
        row=rasterTable.GetRow(i)
        Dim ' Assuming the raster is 8-bit As uvRenderer.AddValue(0,i,Convert.ToByte(row.get_Value(1))).
        uvRenderer.set_Label(0, i, Convert.ToString(row.get_Value(1)))
        fillSymbol=New SimpleFillSymbolClass()
        fillSymbol.Color=colorRamp.get_Color(i)
        uvRenderer.set_Symbol(0, i, CType(fillSymbol, ISymbol))
    Next
    Return rasterRenderer
    Catch ex As Exception
    System.Diagnostics.Debug.WriteLine(ex.Message)
    Return Nothing
    End Try
End Function

}

See Also:

How to create a raster layer

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To use the code in this topic, reference the following assemblies in your Visual Studio project. In the code files, you will need using (C#) or Imports (VB .NET) directives for the corresponding namespaces (given in parenthesis below if different from the assembly name):

• ESRI.ArcGIS.System (ESRI.ArcGIS.esriSystem)
• ESRI.ArcGIS.Display
• ESRI.ArcGIS.Geometry
• ESRI.ArcGIS.DataSourcesGDB
• ESRI.ArcGIS.Geodatabase
• ESRI.ArcGIS.DataSourcesRaster
• ESRI.ArcGIS.Carto

Development licensing	Deployment licensing
ArcGIS Desktop Standard	ArcGIS Desktop Advanced
ArcGIS Desktop Standard	ArcGIS Desktop Standard
ArcGIS Desktop Basic	ArcGIS Desktop Basic
Engine Developer Kit	Engine