-----------------------------------------------SampleMap.vbhtml-------------------------------------------------------

<div class="twelve columns" id="main" style="width: auto;">
    <div id="map" style="float: right; width: 100%; margin-top: 5px;">
        @Code                                                               
                        
            Dim i As Integer
            
            Dim connectString As String = ConfigurationManager.ConnectionStrings("Connection").ConnectionString.ToString
            Dim tableName As String = "TblName" 'Table Name for getting geo data
            Dim tableField As String = "id" 'Field from the table for display geo map
            Dim srid As Integer = "32723"
            
            'Initialize the map and it's properties
            Dim oid As Integer = 0
            Dim MapBuilder = Html.ThinkGeo.Map("Map1", New System.Web.UI.WebControls.Unit(100, System.Web.UI.WebControls.UnitType.Percentage), 530)
            MapBuilder.MapBackground(New BackgroundLayer(New GeoSolidBrush(GeoColor.FromHtml("#E5E3DF"))))
            MapBuilder.MapUnit(GeographyUnit.Meter)
            MapBuilder.MapTools(Sub(tools)
                                        tools.OverlaySwitcherMapTool().Enabled(true)
                                        tools.MouseCoordinateMapTool().Enabled(True)
                                        tools.KeyboardMapTool().Enabled(True)
                                        tools.LoadingImageMapTool().Enabled(True)
                                End Sub)
                                                
            MapBuilder.CurrentExtent(-5297892.20116, 7001997.4056, -2500796.18635, 3026987.386962)

            MapBuilder.CustomOverlays(Sub(overlays)
                                              overlays.GoogleOverlay("Google Map").JavaScriptLibraryUri(New Uri(ConfigurationManager.AppSettings("GoogleUriV3"))).GoogleMapType(GoogleMapType.Normal)
                                          
                                              '=========Load Images on Map
                                              Global.MvcGEO.MultiGeoRasterLayer.BuildReferenceFile(Server.MapPath("~\App_Data\6000\referenceFile.txt"), Server.MapPath("~\App_Data\6000\"))
                                              Dim multiGeoRasterLayer As Global.MvcGEO.MultiGeoRasterLayer = New Global.MvcGEO.MultiGeoRasterLayer(Server.MapPath("~\App_Data\6000\referenceFile.txt"))                                              
                                              overlays.LayerOverlay("multiGeoRasterLayer").Layer("multiGeoRasterLayer", multiGeoRasterLayer).IsBaseOverlay(False).TileType(TileType.MultipleTile).IsVisible(True)

					      '=========Load map for Mapa_Beiral
                                              Dim Mapa_Beiral As MsSql2008FeatureLayer = New MsSql2008FeatureLayer(connectString, "Mapa_Beiral", "geodb_oid", 32723)
                                              Mapa_Beiral.Open()
                                              Mapa_Beiral.ZoomLevelSet.ZoomLevel01.DefaultAreaStyle = AreaStyles.CreateSimpleAreaStyle(GeoColor.StandardColors.DarkBlue)
                                              Mapa_Beiral.ZoomLevelSet.ZoomLevel01.ApplyUntilZoomLevel = ApplyUntilZoomLevel.Level20
                                              
                                              Dim proj1 As Proj4Projection = New Proj4Projection()
                                              proj1.InternalProjectionParametersString = Proj4Projection.GetEpsgParametersString(32723)
                                              proj1.ExternalProjectionParametersString = Proj4Projection.GetGoogleMapParametersString()
                                              proj1.Open()
                                              Mapa_Beiral.FeatureSource.Projection = proj1                                              
                                              overlays.LayerOverlay("Mapa Beiral", False, TileType.SingleTile).Layer(Mapa_Beiral).IsVisible(False)

					      'I am using 6 overlays.Layeroverlay using above code

 End Sub).OnClientClick("mapClickToEdit").Render()

</div>

-------------------------------------------HomeController.vb------------------------------------------------------------------

'There is one more class in this file "HomeController" which Inherits System.Web.Mvc.Controller and other logic related to project are in this class

Public Class MultiGeoRasterLayer
    Inherits Layer

   Private rasterRefrencePathFileName1 As String
    Private spatialIndex As STRtree
    Private upperScale1 As Double
    Private lowerScale1 As Double
    Private boundingBox As RectangleShape

    Private Const upperLeftXPosition As Integer = 0
    Private Const upperLeftYPosition As Integer = 2
    Private Const lowerRightXPosition As Integer = 1
    Private Const lowerRightYPosition As Integer = 3
    Private Const pathFileNamePosition As Integer = 4

    Public Sub DrawImage(map As Map)
        Dim multiGeoRasterLayer As New MultiGeoRasterLayer("D:\Projects\App_Data\6000\referenceFile.txt")
        Dim overlay As New LayerOverlay("multiGeoRasterLayer", False, TileType.MultipleTile)
        overlay.IsBaseOverlay = False
        overlay.Layers.Add(multiGeoRasterLayer)
        map.CustomOverlays.Add(overlay)
    End Sub

    Public Sub New()
        Me.New(String.Empty, Double.MaxValue, Double.MinValue)
    End Sub

    Public Sub New(rasterRefrencePathFileName1 As String)
        Me.New(rasterRefrencePathFileName1, Double.MaxValue, Double.MinValue)
    End Sub

    Public Sub New(rasterRefrencePathFileName As String, upperScale As Double, lowerScale As Double)
        Me.RasterRefrencePathFileName = rasterRefrencePathFileName
        Me.UpperScale = upperScale
        Me.LowerScale = lowerScale
        boundingBox = New RectangleShape()
    End Sub

    Public Property RasterRefrencePathFileName() As String
        Get
            Return rasterRefrencePathFileName1
        End Get
        Set(value As String)
            rasterRefrencePathFileName1 = value
        End Set
    End Property

    Public Property UpperScale() As Double
        Get
            Return upperScale1
        End Get
        Set(value As Double)
            upperScale1 = value
        End Set
    End Property

    Public Property LowerScale() As Double
        Get
            Return lowerScale1
        End Get
        Set(value As Double)
            lowerScale1 = value
        End Set
    End Property

    Protected Overrides Sub OpenCore()
        If File.Exists(RasterRefrencePathFileName) Then
            Dim rasterFiles As String() = File.ReadAllLines(RasterRefrencePathFileName)
            spatialIndex = New STRtree(rasterFiles.Length)

            Dim boundingBoxes As New Collection(Of ThinkGeo.MapSuite.Core.BaseShape)()

            For Each rasterLine As String In rasterFiles
                Dim parts As String() = rasterLine.Split(New String() {","}, StringSplitOptions.None)
                Dim rasterBoundingBox As New RectangleShape(New PointShape(Double.Parse(parts(upperLeftXPosition)), Double.Parse(parts(upperLeftYPosition))), New PointShape(Double.Parse(parts(lowerRightXPosition)), Double.Parse(parts(lowerRightYPosition))))
                Dim envelope As New Envelope(Double.Parse(parts(upperLeftXPosition)), Double.Parse(parts(lowerRightXPosition)), Double.Parse(parts(upperLeftYPosition)), Double.Parse(parts(lowerRightYPosition)))
                spatialIndex.Insert(envelope, parts(pathFileNamePosition))
            Next
            spatialIndex.Build()
            boundingBox = ExtentHelper.GetBoundingBoxOfItems(boundingBoxes)
        Else
            Throw New FileNotFoundException("The Raster reference file could not be found.", RasterRefrencePathFileName)
        End If
    End Sub

    Protected Overloads Sub CloseCore()
        spatialIndex = Nothing
    End Sub

    Protected Overrides Sub DrawCore(canvas As GeoCanvas, labelsInAllLayers As Collection(Of SimpleCandidate))     
      
        Dim currentScale As Double = ExtentHelper.GetScale(canvas.CurrentWorldExtent, canvas.Width, canvas.MapUnit)

        If currentScale >= LowerScale AndAlso currentScale <= UpperScale Then
            Dim currentExtent As RectangleShape = canvas.CurrentWorldExtent
            Dim currentExtentEnvelope As New Envelope(currentExtent.UpperLeftPoint.X, currentExtent.LowerRightPoint.X, currentExtent.UpperLeftPoint.Y, currentExtent.LowerRightPoint.Y)
            Dim rasters As ArrayList = DirectCast(spatialIndex.Query(currentExtentEnvelope), ArrayList)

            For Each file As String In rasters
                Dim rasterRasterLayer As New GdiPlusRasterLayer(file)
                rasterRasterLayer.Open()
                rasterRasterLayer.Draw(canvas, labelsInAllLayers)
                rasterRasterLayer.Close()
               
            Next
        End If
    End Sub

    Public Overrides ReadOnly Property HasBoundingBox() As Boolean
        Get
            Return True
        End Get
    End Property

    Protected Overrides Function GetBoundingBoxCore() As RectangleShape
        Return boundingBox
    End Function

    Public Shared Sub BuildReferenceFile(newReferencepathFileName As String, pathOfRasterFiles As String)
        Try
            If Directory.Exists(pathOfRasterFiles) Then
                Dim files As String() = Directory.GetFiles(pathOfRasterFiles, "*.tif")
                Dim streamWriter As StreamWriter = Nothing

                Try
                    streamWriter = System.IO.File.CreateText(newReferencepathFileName)

                    For Each file As String In files
                        If System.IO.File.Exists(file) Then
                            Dim rasterRasterLayer As New GdiPlusRasterLayer(file)
                            rasterRasterLayer.Open()
                            Dim boundingBox As New RectangleShape()
                            boundingBox = rasterRasterLayer.GetBoundingBox()
                            rasterRasterLayer.Close()
                            streamWriter.WriteLine(String.Format("{0},{1},{2},{3},{4}", boundingBox.UpperLeftPoint.X, boundingBox.LowerRightPoint.X, boundingBox.UpperLeftPoint.Y, boundingBox.LowerRightPoint.Y, file))
                        End If
                    Next
                    streamWriter.Close()
                Catch ex As Exception

                Finally
                    If streamWriter IsNot Nothing Then
                        streamWriter.Dispose()
                    End If
                End Try
            Else
                Throw New DirectoryNotFoundException("The path containing the Raster files could not be found.")
            End If
        Catch ex As Exception

        End Try
    End Sub

    Private Overloads Sub DrawCore(map As Map)
        Throw New NotImplementedException
    End Sub   

End Class