为什么不一样的标，生成的点竟然在同一个位置？

<P>请教大家一个问题，我想把经纬度的两个坐标，生成点，有什么需要特别设置的地方吗？ 比如点113.7833333,40.2833333和点113.8833333,40.0500000生成的两个点是一个位置，这是什么原因呢？ </P>

没什么特别设置,最好把你代码贴出来看看

<P>Private Sub Command3_Click()<BR>On Error GoTo ErrorHandler:</P>
<P>   filename = "PointLayer"<BR>   Set pFeatureWorkspace = SDEConnect("xuye", "5151", "DB_GWS_SDE", "sde", "sde")<BR>    CreateFeature pFeatureWorkspace, filename, esriGeometryType.esriGeometryPoint<BR>    MsgBox "Create Layer OK"<BR> <BR>  Set pClass = pFeatureWorkspace.OpenFeatureClass(filename)</P>
<P>  '''''''''''''''''''''''''''''''''''''<BR>    Set pLayer = New FeatureLayer<BR>    Set pLayer.FeatureClass = pClass<BR>    Set pWorkspaceEdit = pFeatureWorkspace  <BR>''''''''''''''''''''''''''''''开始编辑<BR>    pWorkspaceEdit.StartEditing True<BR>'''''''''''''''''''''''''''''''<BR>   <BR>''''''''''''''''''''''''''''''''循环添加点<BR> ReadPoint App.Path ; "\output\ToPoint.txt", esriGeometryType.esriGeometryPoint<BR>    <BR>    Dim i As Integer<BR>    For i = 0 To UBound(X) - 1<BR>       Set pFeature = pClass.CreateFeature<BR>        Set pPoint = New Point<BR>        pPoint.X = CDbl(Trim(X(i)))<BR>        pPoint.Y = CDbl(Trim(Y(i)))<BR>        <BR>        Set pFeature.Shape = pPoint<BR>        pFeature.Store<BR>    Next<BR>    MsgBox "create Point OK"<BR>    <BR>    Dim m_pFeatureLayer As IFeatureLayer<BR>    Set m_pFeatureLayer = New FeatureLayer<BR>    Set m_pFeatureLayer.FeatureClass = pClass<BR>    m_pFeatureLayer.Name = pClass.AliasName<BR>    '装载要素层<BR>    MapControl1.ClearLayers<BR>    MapControl1.AddLayer m_pFeatureLayer<BR>    MsgBox "Load Layer OK"<BR>ErrorHandler:<BR>        MsgBox Err.Description<BR>End Sub<BR></P>
<P>'创建新图层</P>
<P>Public Sub CreateFeature(pFeatureWorkspace As IFeatureWorkspace, className As String, geomType As esriGeometryType)</P>
<P>Dim pFields As IFields<BR>Dim pFieldsEdit As IFieldsEdit<BR>Set pFields = New esriGeoDatabase.Fields<BR>Set pFieldsEdit = pFields</P>
<P>Dim pField As IField<BR>Dim pFieldEdit As IFieldEdit</P>
<P>' 添加一个几何字段<BR>Set pField = New esriGeoDatabase.Field<BR>Set pFieldEdit = pField<BR>pFieldEdit.Name = "Shape"<BR>pFieldEdit.Type = esriFieldTypeGeometry</P>
<P>Dim pGeomDef As IGeometryDef<BR>Dim pGeomDefEdit As IGeometryDefEdit</P>
<P>Dim pSR As ISpatialReference<BR>Set pSR = New UnknownCoordinateSystem</P>
<P>Set pGeomDef = New GeometryDef<BR>Set pGeomDefEdit = pGeomDef<BR>With pGeomDefEdit<BR>    .GeometryType = geomType<BR>    .GridCount = 2<BR>    .GridSize(0) = 10000<BR>    .AvgNumPoints = 0<BR> Set .SpatialReference = pSR<BR>End With</P>
<P><BR>'在创建孤立的要素类时必须指定<BR> <BR>Set pFieldEdit.GeometryDef = pGeomDef<BR>pFieldsEdit.AddField pField</P>
<P>Set pField = New esriGeoDatabase.Field<BR>Set pFieldEdit = pField<BR>With pFieldEdit<BR>.length = 30<BR>.Name = "FID"<BR>.Type = esriFieldTypeOID<BR>End With<BR>pFieldsEdit.AddField pField</P>
<P>Set pField = New esriGeoDatabase.Field<BR>Set pFieldEdit = pField<BR>With pFieldEdit<BR>.length = 30<BR>.Name = "ID"<BR>.Type = esriFieldTypeString<BR>End With<BR>pFieldsEdit.AddField pField</P>
<P>'创建要素类<BR>Dim pOutFeatureClass As IFeatureClass<BR>Set pOutFeatureClass = pFeatureWorkspace.CreateFeatureClass(className, pFieldsEdit, Nothing, Nothing, esriFTSimple, "shape", "")<BR>End Sub</P>
<P>经纬度的点集生成的图层</P>
<P><IMG src="http://bbs.esrichina-bj.cn/ESRI/attachments/forumid_26/snap_FYyfhvJwx9Pg.gif" border=0></P>
<P>直角坐标生成的图层</P>

<P><IMG src="http://bbs.esrichina-bj.cn/ESRI/attachments/forumid_26/snap1_V8hpab8fHncb.gif" border=0></P>
<P>它们的数据源是相同的，经纬度的点集生成的图明显就不对，好多点都是叠在一起的</P>

我觉得没有什么不对，可能是它们的坐标比较接近，在一定的比例下在屏幕上显示起来好像叠在一起，你放大看一下试试

<P>可能是你数据转换过程中的问题；</P>
<P>在vb中将前台录入的文本数据用cdbl转换为double类型存储,在转换大数时会发生数据精度溢出的问题 <BR>如cdbl(99999999999999.999999)后数据变为了100000000000000.000000</P>