/// <summary>
/// 计算最高点值
/// </summary>
/// <param name="envelope">计算范围</param>
/// <returns>最高点高程</returns>
/// <remarks>计算方式为在区域内按步长值依次选取采样点，求最大值</remarks>
protected double GetTopValue(IPolygon calcPolygon)
{
IPolygon polygon = calcPolygon.Clone2(gviVertexAttribute.gviVertexAttributeNone) as IPolygon;
IEnvelope envelope = polygon.Envelope;
// 采样点数量 可根据精度修改
const double pickCount = 10000;
// 高程计算模式
gviGetElevationType mode = gviGetElevationType.gviGetElevationFromDatabase;
// 最高点高程值和位置
double topValue = double.MinValue;
double topPointX = double.MinValue, topPointY = double.MinValue;
double step = Math.Sqrt(envelope.Width * envelope.Height / pickCount);
double xStart = envelope.MinX;
double yStart = envelope.MinY;
bool hasTopPoint = false;
while (xStart <= envelope.MaxX)
{
yStart = envelope.MinY;
while (yStart <= envelope.MaxY)
{
double elevatation = _AxRenderControl.Terrain.GetElevation(xStart, yStart, mode);
IGeometryFactory factory = new GeometryFactory();
IPoint point = factory.CreatePoint(gviVertexAttribute.gviVertexAttributeNone);
IVector3 vector = new Vector3();
vector.Set(xStart, yStart, 0);
point.Position = vector;
bool pointOnSurface = (polygon.IsPointOnSurface(point));
if (topValue < elevatation && pointOnSurface)
{
topValue = elevatation;
topPointX = xStart;
topPointY = yStart;
hasTopPoint = true;
}
yStart += step;
}
xStart += step;
}
//MessageBox.Show(string.Format("最高点高度：{0}。坐标为X:{1} Y:{2} Z:{3}：", topValue, topPointX, topPointY, topValue));
if (hasTopPoint)
{
DrawTableLabel(topPointX, topPointY, topValue);
DrawTopPoint(topPointX, topPointY, topValue);
}
return(topValue);
}
void axRenderControl1_RcMouseClickSelect(IPickResult PickResult, IPoint IntersectPoint, gviModKeyMask Mask, gviMouseSelectMode EventSender)
{
if (PickResult.Type == gviObjectType.gviObjectTerrain)
{
gviGetElevationType mode = gviGetElevationType.gviGetElevationFromMemory;
switch (this.toolStripGetElevationType.Text)
{
case "GetElevationFromMemory":
mode = gviGetElevationType.gviGetElevationFromMemory;
break;
case "GetElevationFromDatabase":
mode = gviGetElevationType.gviGetElevationFromDatabase;
break;
}
double elevatation = this.axRenderControl1.Terrain.GetElevation(IntersectPoint.X, IntersectPoint.Y, mode);
MessageBox.Show("当前位置高程为:" + elevatation.ToString());
}
}