ARCMAP的编辑工具---草图工具-----弧线工具。在图形窗口定义第一点，作为圆弧的起点，定义第二点作为圆弧的轴线。在定义第三点做为圆弧的终点。请问定义终点的时候怎么确定圆弧的弧长？或者说怎么确定弧线的拱高？？ARCMAP里面有提供输入弧线数据的功能没有？？请教大吓。。。

arcmap提供几种arc的绘制方法

下面是例子里的一个东东

IEllipticArc Example

 Public Sub Test()

     ' Get the Application Handle and the display

     Dim pMxApp As IMxApplication, pSDisplay As IScreenDisplay

     Set pMxApp = MxApplication

     Set pSDisplay = pMxApp.Display

     'Use IEllipticArc.PutCoords to Input the Center, Start and End points to create an EllipticArc.

     Dim pCPt As IPoint, pSPt As IPoint, pEPt As IPoint

     Set pSPt = eCreatePoint(100, 100)

     Set pCPt = eCreatePoint(250, 100)

     Set pEPt = eCreatePoint(400, 100)

     Dim pEllipticArc As IEllipticArc

     Set pEllipticArc = New EllipticArc

     'Draw a Elliptic arc with Solid line symbol.

     pEllipticArc.PutCoords False, pCPt, pSPt, pEPt, 3.14, 1 / 3, esriArcClockwise

     DisplayArc pMxApp, pSDisplay, pEllipticArc, esriSLSSolid

     'Use IEllipticArc.QueryCoords to get the statistics of the elliptic arc.

     Dim pEArc As IEllipticArc

     Set pEArc = pEllipticArc

     Dim NL As String, TB As String

     NL = Chr(13) ; Chr(10)    ' Define newline.

     TB = Chr(9)    ' Define tab

     MsgBox "The statistics of the Elliptic arc are: " + NL + _

            "Center Point : " + NL + _

            "  X coord: " + TB + Str(pEArc.CenterPoint.x) + NL + _

            "  Y coord: " + TB + Str(pEArc.CenterPoint.y) + NL + _

            "IsCircular: " + TB + Str(pEArc.IsCircular) + NL + _

            "From Angle: " + TB + Str(pEArc.fromAngle(False)) + NL + _

            "Central Angle: " + TB + Str(pEArc.CentralAngle) + NL + _

            "To Angle: " + TB + Str(pEArc.ToAngle(False)) + NL + _

            "IsLine: " + TB + Str(pEArc.IsLine) + NL + _

            "IsPoint: " + TB + Str(pEArc.IsPoint) + NL + _

            "IsMinor: " + TB + Str(pEArc.isMinor) + NL + _

            "IsCCW: " + TB + Str(pEArc.IsCounterClockwise)

 End Sub

 Public Function eSimpleLine(currStyle) As ISimpleLineSymbol

     Set eSimpleLine = New SimpleLineSymbol

     eSimpleLine.Style = currStyle

 End Function

 Public Sub DisplayArc(pMxApp As IMxApplication, pSDisplay As IScreenDisplay, pEArc As IEllipticArc, currStyle)

     Dim lOldActiveCache As Long

     lOldActiveCache = pSDisplay.ActiveCache

     'Add the new arc to a segment collection.

     Dim pSeg As ISegment

     Set pSeg = pEArc

     Dim pPolyline As ISegmentCollection

     Set pPolyline = New Polyline

     pPolyline.AddSegment pSeg

     With pSDisplay

        .ActiveCache = esriNoScreenCache  ' esriNoScreenCache = -1

        .StartDrawing pMxApp.Display.hDC, esriNoScreenCache

        .SetSymbol eSimpleLine(currStyle)

        .DrawPolyline pPolyline

        .FinishDrawing

        .ActiveCache = lOldActiveCache

     End With

 End Sub

 Public Function eCreatePoint(x As Double, y As Double) As IPoint

     Set eCreatePoint = New Point

     eCreatePoint.PutCoords x, y

 End Function