C++、GDAL创建shapefile,并向矢量文件中添加网格

Posted on 2013-07-30 18:16  冰天雪域  阅读(897)  评论(0编辑  收藏  举报
//总体来说这个过程就是构建数据源->构建层->构建要素->构建形状->关闭数据源。
//要包含的GDAL头文件
#include <gdal_priv.h>
#include <ogrsf_frmts.h>
#include <iostream>
using namespace std;

#pragma comment(lib,"gdal_i.lib")
bool Creatshape(const char* pszFileName ,int line,int row);

#include <tchar.h>  //_TCHAR* 类型在该头文件里
int _tmain(int argc, _TCHAR* argv[])
{
	const char *pszFileName="C:\\Users\\Public\\Pictures\\Sample Pictures\\srtm_51_03.tif";
	Creatshape(pszFileName,7,9);
	system("pause");
	return 0;
}
/************************************************************************/
/*创建过程:构建数据源->构建层->构建要素->构建形状->关闭数据源
/* 参数pszFileName 为输入的文件名
参数linenum为划分的行数
参数rows为划分的列数*/
/************************************************************************/
bool Creatshape(const char* pszFileName ,int linenum,int rows)
{
	//获取影像信息
	GDALDataset *poDataSet;
	GDALAllRegister();  
	CPLSetConfigOption("GDAL_FILENAME_IS_UTF8","NO");
	poDataSet=(GDALDataset*)GDALOpen(pszFileName,GA_ReadOnly); //打开数据集
 	if (poDataSet==NULL)
	{
		"Failed to open this dataset!"; //代开失败的话则给出提示并退出
		exit(1);
	}
	double Trans[6];//坐标转换参数数组,作为GetGeoTransform()函数的参数
	int width,height; //影像的像行列数;
	width=poDataSet->GetRasterXSize(); //获取影像列数,为后续划分网格做准备
	height=poDataSet->GetRasterYSize();//获取影像行数,为后续划分网格做准备
	poDataSet->GetGeoTransform(Trans);

	for (int i=0;i<6;i++)
	{
		cout<<Trans[i]<<endl;  //循环输出仿射变换参数;
	}
	//注册shape文件驱动
	const char* pszDriverName="ESRI Shapefile";
	OGRSFDriver *poDriver;
	OGRRegisterAll();
	poDriver=OGRSFDriverRegistrar::GetRegistrar()->GetDriverByName(pszDriverName);
	if (poDriver==NULL)
	{
		printf("%s driver is not available!",pszDriverName);
		exit(1);
	}
	//创建shape文件;
	OGRDataSource *poDS;
	//创建一个叫myshapefile的目录,存放生成的文件;
	//如果名字有.shp后缀,则直接在当前目录下生成文件;
	poDS=poDriver->CreateDataSource("myshapefile.shp",NULL); 
	if (poDS==NULL)
	{
		printf("Create my shape file failed!");
		exit(1);
	}
	//创建输出图层;
	OGRLayer *poLayer;;
	const char *prj=poDataSet->GetProjectionRef(); //获取栅格影像的空间参考信息
	cout<<"栅格数据空间参考信息为:\n"<<prj<<endl<<endl;
	OGRSpatialReference oSRS;  
	oSRS.SetFromUserInput(prj);  //将获得的空间参考信息字符串做为文本一次性赋给矢量数据的OGRSpatialReference对象;
	poLayer=poDS->CreateLayer(pszFileName,&oSRS, wkbUnknown, NULL);
	if (poLayer==NULL)
	{
		printf("Creat layer failed!");
		exit(1);
	}
	//创建层数据的属性fields;
	OGRFieldDefn oField("Point",OFTString);
	oField.SetWidth(10);
	if (poLayer->CreateField(&oField)!=OGRERR_NONE)
	{
		printf("Create Point Field Failed!");
		exit(1);
	}
	//创建features,写入feature到磁盘;
	OGRFeature *poFeature;
	poFeature=OGRFeature::CreateFeature(poLayer->GetLayerDefn());
	//绘制外边框
	OGRLineString Line;
	OGRPoint Point1(Trans[0],Trans[3]); 
	OGRPoint Point2(Trans[0]+width*Trans[1],Trans[3]);
	OGRPoint Point3(Trans[0]+width*Trans[1],Trans[3]+width*Trans[4]+height*Trans[5]);
	OGRPoint Point4(Trans[0],Trans[3]+width*Trans[4]+height*Trans[5]);//四个角点的地理坐标,通过行列号计算地理坐标,是通过六参数得到的;
	Line.addPoint(&Point1);
	Line.addPoint(&Point2);
	Line.addPoint(&Point3);
	Line.addPoint(&Point4);
	Line.addPoint(&Point1);
	//水平方向加线;
	OGRLineString SubHline[50];
	OGRPoint PointLeft[50],PointRight[50];
	for (int i=1;i<linenum;i++)
	{
		PointLeft[i].setX(Trans[0]); //设置左边框上要加线的起点X坐标
		PointLeft[i].setY((Point4.getY()-Trans[3])/linenum*i+Trans[3]);//设置左边框上要加线的起点Y坐标
		PointRight[i].setX(Point2.getX());//设置右边框上要加线的起点X坐标
		PointRight[i].setY((Point4.getY()-Trans[3])/linenum*i+Trans[3]);//设置右边框上要加线的起点Y坐标
	}
	for (int i=1;i<linenum;i++)
	{  
		SubHline[i].addPoint(&PointLeft[i]); //左边框上加点;
		SubHline[i].addPoint(&PointRight[i]);//右边框上加点;
		if (i<linenum-1)
		{
			SubHline[i].addPoint(&PointRight[i+1]); //从右边框的上一点转到下一点,避免交叉斜线的出现;
		}
		Line.addSubLineString(&SubHline[i]);//将SubHline数组中的每一个线做为子线段添加到Line对象中;
	}
	Line.addPoint(&Point2);
	//垂直方向加线
	OGRLineString SubVline[50];
	OGRPoint PointUp[50],PointDown[50];
	for (int j=1;j<rows;j++)
	{
		//添加上边框上的点;
		PointUp[j].setX((Point2.getX()-Trans[0])/rows*j+Trans[0]);
		PointUp[j].setY(Trans[3]);
		//添加下边框上的点;
		PointDown[j].setX((Point2.getX()-Trans[0])/rows*j+Trans[0]);
		PointDown[j].setY(Point4.getY());
	}
	for (int j=1;j<rows;j++)
	{
		SubVline[j].addPoint(&PointUp[j]);
		SubVline[j].addPoint(&PointDown[j]);
		if (j<rows-1)
		{
			SubVline[j].addPoint(&PointDown[j+1]); //从下边框的前一点转到后一点,避免交叉斜线的出现;
		}
		Line.addSubLineString(&SubVline[j]);
	}
	//poFeature->SetGeometryDirectly(&Line);//问题出在这啊!!用SetGeometryDirectly报错,要用SetGeometry
	poFeature->SetGeometry(&Line);
	if (poLayer->CreateFeature(poFeature)!=OGRERR_NONE)
	{
		printf("Failed create feature in shapefile!");
		exit(1);
	}
	OGRFeature::DestroyFeature(poFeature);
	OGRDataSource::DestroyDataSource(poDS);
	printf("创建矢量数据成功!\n");
	system("pause");
	return TRUE;
}


用ENVI打开生成的shp文件:

 

 

 

注意:在计算四个角点的坐标时,用到了六参数,参考博客:http://blog.csdn.net/ivanljf/article/details/9226463

 

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