GDAL\OGR读取数据示例 C#版本
首先创建一个Windows窗体应用程序，然后拖几个按钮和文本框，如下图所示。第一行用来显示栅格数据的路径，点击浏览找到一个栅格文件，将路径显示在文本框中，然后点击读取，将图像的基本信息显示在最下方的富文本框中；第二行的类似，显示的是矢量数据的信息。
1、添加GDALC#版本的引用，注意只添加后面是_csharp.dll的四个文件。如下图所示。
2、添加浏览按钮的事件，代码如下：
private void buttonRaster_Click(object sender, EventArgs e)
{
OpenFileDialog ofd = new OpenFileDialog();
ofd.Title = "打开栅格文件";
ofd.Filter = @"Erdas Imagine (*.img)|*.img|
GeoTiff (*.tif *.tiff)|*.tif *.tiff|
PCIDSK (*.pix)|*.pix|
EarthWatch/DigitalGlobe (*.til)|*.til|
HDF (*.hdf *.h5 *he5)|*.hdf *.h5 *he5|
NITF (*.ntf *.nsf)|*.ntf *.nsf|
Spot DIMAP (metadata.dim)|metadata.dim|
位图文件 (*.bmp)|*.bmp|
Graphics Interchange Format (*.gif)|*.gif|
JPEG (*.jpg *.jpeg)|*.jpg *.jpeg|
Portable Network Graphics (*.png)|*.png|
Web Map Servers (*.xml)|*.xml|所有文件|*.*";
ofd.ShowDialog();
textBoxRaster.Text = ofd.FileName;
}
private void buttonVector_Click(object sender, EventArgs e)
{
OpenFileDialog ofd = new OpenFileDialog();
ofd.Title = "打开矢量文件";
ofd.Filter = @"ESRI Shapefile(*.shp)|*.shp|
MapInfo File(*.mid *.mif *.tab)|*.mid *.mif *tab|
Arc/Info .E00 (*.e00)|*.e00|
AutoCAD DXF(*.dxf)|*.dxf|
Comma Separated Value (.csv)|*.csv|
GML(*.gml)|*.gml|
KML(*.kml)|*.kml|
所有文件|*.*";
ofd.ShowDialog();
textBoxVector.Text = ofd.FileName;
}
3、添加读取栅格和矢量数据信息的代码，分别存在GDALReadFile.cs和OGRReadFile.cs文件中。具体代码见下面：
首先是GDALReadFile.cs
using OSGeo.GDAL;
using OSGeo.OSR;
using System;
namespace GDALTest
{
/// <summary>
/// 使用GDAL读取栅格数据信息类
/// </summary>
public class GDALReadFile
{
public static string GetRasterInfo(string strFilePath)
{
string strInfomation = "";
try
{
/* -------------------------------------------------------------------- */
/* Register driver(s). */
/* -------------------------------------------------------------------- */
Gdal.AllRegister();
/* -------------------------------------------------------------------- */
/* Open dataset. */
/* -------------------------------------------------------------------- */
Dataset ds = Gdal.Open(strFilePath, Access.GA_ReadOnly);
if (ds == null)
{
strInfomation = ("Can't open " + strFilePath);
return strInfomation;
}
strInfomation += ("Raster dataset parameters:\n");
strInfomation += (" Projection: " + ds.GetProjectionRef() + "\n");
strInfomation += (" RasterCount: " + ds.RasterCount.ToString() + "\n");
strInfomation += (" RasterSize (" + ds.RasterXSize.ToString() + "," + ds.RasterYSize.ToString() + ")" + "\n");
/* -------------------------------------------------------------------- */
/* Get driver */
/* -------------------------------------------------------------------- */
Driver drv = ds.GetDriver();
if (drv == null)
{
strInfomation += ("Can't get driver.");
return strInfomation;
}
strInfomation += ("Using driver " + drv.LongName);
/* -------------------------------------------------------------------- */
/* Get metadata */
/* -------------------------------------------------------------------- */
string[] metadata = ds.GetMetadata("");
if (metadata.Length > 0)
{
strInfomation += (" Metadata:");
for (int iMeta = 0; iMeta < metadata.Length; iMeta++)
{
strInfomation += (" " + iMeta.ToString() + ": " + metadata[iMeta] + "\n");
}
strInfomation += ("\n");
}
/* -------------------------------------------------------------------- */
/* Report "IMAGE_STRUCTURE" metadata. */
/* -------------------------------------------------------------------- */
metadata = ds.GetMetadata("IMAGE_STRUCTURE");
if (metadata.Length > 0)
{
strInfomation += (" Image Structure Metadata:" + "\n");
for (int iMeta = 0; iMeta < metadata.Length; iMeta++)
{
strInfomation += (" " + iMeta.ToString() + ": " + metadata[iMeta] + "\n");
}
strInfomation += ("\n");
}
/* -------------------------------------------------------------------- */
/* Report subdatasets. */
/* -------------------------------------------------------------------- */
metadata = ds.GetMetadata("SUBDATASETS");
if (metadata.Length > 0)
{
strInfomation += (" Subdatasets:\n");
for (int iMeta = 0; iMeta < metadata.Length; iMeta++)
{
strInfomation += (" " + iMeta.ToString() + ": " + metadata[iMeta] + "\n");
}
strInfomation += ("\n");
}
/* -------------------------------------------------------------------- */
/* Report geolocation. */
/* -------------------------------------------------------------------- */
metadata = ds.GetMetadata("GEOLOCATION");
if (metadata.Length > 0)
{
strInfomation += (" Geolocation:\n");
for (int iMeta = 0; iMeta < metadata.Length; iMeta++)
{
strInfomation += (" " + iMeta.ToString() + ": " + metadata[iMeta] + "\n");
}
strInfomation += ("\n");
}
/* -------------------------------------------------------------------- */
/* Report corners. */
/* -------------------------------------------------------------------- */
strInfomation += ("Corner Coordinates:\n");
strInfomation += (" Upper Left (" + GDALInfoGetPosition(ds, 0.0, 0.0) + ")" + "\n");
strInfomation += (" Lower Left (" + GDALInfoGetPosition(ds, 0.0, ds.RasterYSize) + ")" + "\n");
strInfomation += (" Upper Right (" + GDALInfoGetPosition(ds, ds.RasterXSize, 0.0) + ")" + "\n");
strInfomation += (" Lower Right (" + GDALInfoGetPosition(ds, ds.RasterXSize, ds.RasterYSize) + ")" + "\n");
strInfomation += (" Center (" + GDALInfoGetPosition(ds, ds.RasterXSize / 2, ds.RasterYSize / 2) + ")" + "\n");
strInfomation += ("\n");
/* -------------------------------------------------------------------- */
/* Report projection. */
/* -------------------------------------------------------------------- */
string projection = ds.GetProjectionRef();
if (projection != null)
{
SpatialReference srs = new SpatialReference(null);
if (srs.ImportFromWkt(ref projection) == 0)
{
string wkt;
srs.ExportToPrettyWkt(out wkt, 0);
strInfomation += ("Coordinate System is:\n");
strInfomation += (wkt);
}
else
{
strInfomation += ("Coordinate System is:\n");
strInfomation += (projection);
}
}
/* -------------------------------------------------------------------- */
/* Report GCPs. */
/* -------------------------------------------------------------------- */
if (ds.GetGCPCount() > 0)
{
strInfomation += ("GCP Projection: " + ds.GetGCPProjection() + "\n");
GCP[] GCPs = ds.GetGCPs();
for (int i = 0; i < ds.GetGCPCount(); i++)
{
strInfomation += ("GCP[" + i.ToString() + "]: Id=" + GCPs[i].Id + ", Info=" + GCPs[i].Info + "\n");
strInfomation += (" (" + GCPs[i].GCPPixel.ToString() + "," + GCPs[i].GCPLine.ToString() + ") -> ("
+ GCPs[i].GCPX.ToString() + "," + GCPs[i].GCPY.ToString() + "," + GCPs[i].GCPZ.ToString() + ")" + "\n");
strInfomation += ("");
}
strInfomation += ("\n");
double[] transform = new double[6];
Gdal.GCPsToGeoTransform(GCPs, transform, 0);
strInfomation += ("GCP Equivalent geotransformation parameters: " + ds.GetGCPProjection() + "\n");
for (int i = 0; i < 6; i++)
strInfomation += ("t[" + i + "] = " + transform[i].ToString() + "\n");
strInfomation += ("\n");
}
/* -------------------------------------------------------------------- */
/* Get raster band */
/* -------------------------------------------------------------------- */
for (int iBand = 1; iBand <= ds.RasterCount; iBand++)
{
Band band = ds.GetRasterBand(iBand);
strInfomation += ("Band " + iBand.ToString() + " :\n");
strInfomation += (" DataType: " + Gdal.GetDataTypeName(band.DataType) + "\n");
strInfomation += (" ColorInterpretation: " + Gdal.GetColorInterpretationName(band.GetRasterColorInterpretation()) + "\n");
ColorTable ct = band.GetRasterColorTable();
if (ct != null)
strInfomation += (" Band has a color table with " + ct.GetCount().ToString() + " entries.\n");
strInfomation += (" Description: " + band.GetDescription() + "\n");
strInfomation += (" Size (" + band.XSize.ToString() + "," + band.YSize.ToString() + ")" + "\n");
int BlockXSize, BlockYSize;
band.GetBlockSize(out BlockXSize, out BlockYSize);
strInfomation += (" BlockSize (" + BlockXSize.ToString() + "," + BlockYSize.ToString() + ")" + "\n");
double val;
int hasval;
band.GetMinimum(out val, out hasval);
if (hasval != 0) strInfomation += (" Minimum: " + val.ToString());
band.GetMaximum(out val, out hasval);
if (hasval != 0) strInfomation += (" Maximum: " + val.ToString());
band.GetNoDataValue(out val, out hasval);
if (hasval != 0) strInfomation += (" NoDataValue: " + val.ToString());
band.GetOffset(out val, out hasval);
if (hasval != 0) strInfomation += (" Offset: " + val.ToString());
band.GetScale(out val, out hasval);
if (hasval != 0) strInfomation += (" Scale: " + val.ToString());
for (int iOver = 0; iOver < band.GetOverviewCount(); iOver++)
{
Band over = band.GetOverview(iOver);
strInfomation += (" OverView " + iOver + " :" + "\n");
strInfomation += (" DataType: " + over.DataType + "\n");
strInfomation += (" Size (" + over.XSize + "," + over.YSize + ")" + "\n");
strInfomation += (" PaletteInterp: " + over.GetRasterColorInterpretation().ToString() + "\n");
}
}
}
catch (Exception e)
{
strInfomation += ("Application error: " + e.Message);
}
return strInfomation;
}
private static string GDALInfoGetPosition(Dataset ds, double x, double y)
{
double[] adfGeoTransform = new double[6];
double dfGeoX, dfGeoY;
ds.GetGeoTransform(adfGeoTransform);
dfGeoX = adfGeoTransform[0] + adfGeoTransform[1] * x + adfGeoTransform[2] * y;
dfGeoY = adfGeoTransform[3] + adfGeoTransform[4] * x + adfGeoTransform[5] * y;
return dfGeoX.ToString() + ", " + dfGeoY.ToString();
}
}
}
接着是OGRReadFile.cs文件：
using OSGeo.OGR;
using OSGeo.OSR;
using System;
/// <summary>
/// 使用OGR读取矢量数据信息类
/// </summary>
public class OGRReadFile
{
public static string GetVectorInfo(string strFilePath)
{
string strInfomation = "";
/* -------------------------------------------------------------------- */
/* Register format(s). */
/* -------------------------------------------------------------------- */
Ogr.RegisterAll();
/* -------------------------------------------------------------------- */
/* Open data source. */
/* -------------------------------------------------------------------- */
DataSource ds = Ogr.Open(strFilePath, 0);
if (ds == null)
{
strInfomation = ("Can't open " + strFilePath);
return strInfomation;
}
/* -------------------------------------------------------------------- */
/* Get driver */
/* -------------------------------------------------------------------- */
Driver drv = ds.GetDriver();
if (drv == null)
{
strInfomation = ("Can't get driver.");
return strInfomation;
}
// TODO: drv.name is still unsafe with lazy initialization (Bug 1339)
strInfomation += ("Using driver " + drv.name);
/* -------------------------------------------------------------------- */
/* Iterating through the layers */
/* -------------------------------------------------------------------- */
for (int iLayer = 0; iLayer < ds.GetLayerCount(); iLayer++)
{
Layer layer = ds.GetLayerByIndex(iLayer);
if (layer == null)
{
strInfomation = ("FAILURE: Couldn't fetch advertised layer " + iLayer);
return strInfomation;
}
strInfomation += ReportLayer(layer);
}
return strInfomation;
}
public static string ReportLayer(Layer layer)
{
string strInfomation = "";
FeatureDefn def = layer.GetLayerDefn();
strInfomation += ("Layer name: " + def.GetName());
strInfomation += ("Feature Count: " + layer.GetFeatureCount(1).ToString());
Envelope ext = new Envelope();
layer.GetExtent(ext, 1);
strInfomation += ("Extent: " + ext.MinX.ToString() + "," + ext.MaxX.ToString() + "," +
ext.MinY.ToString() + "," + ext.MaxY.ToString());
/* -------------------------------------------------------------------- */
/* Reading the spatial reference */
/* -------------------------------------------------------------------- */
OSGeo.OSR.SpatialReference sr = layer.GetSpatialRef();
string srs_wkt;
if (sr != null)
{
sr.ExportToPrettyWkt(out srs_wkt, 1);
}
else
srs_wkt = "(unknown)";
strInfomation += ("Layer SRS WKT: " + srs_wkt);
/* -------------------------------------------------------------------- */
/* Reading the fields */
/* -------------------------------------------------------------------- */
strInfomation += ("Field definition:");
for (int iAttr = 0; iAttr < def.GetFieldCount(); iAttr++)
{
FieldDefn fdef = def.GetFieldDefn(iAttr);
strInfomation += (fdef.GetNameRef() + ": " +
fdef.GetFieldTypeName(fdef.GetFieldType()) + " (" +
fdef.GetWidth().ToString() + "." +
fdef.GetPrecision().ToString() + ")");
}
/* -------------------------------------------------------------------- */
/* Reading the shapes */
/* -------------------------------------------------------------------- */
strInfomation += ("");
Feature feat;
while ((feat = layer.GetNextFeature()) != null)
{
strInfomation += ReportFeature(feat, def);
feat.Dispose();
}
return strInfomation;
}
public static string ReportFeature(Feature feat, FeatureDefn def)
{
string strInfomation = "";
strInfomation += ("Feature(" + def.GetName() + "): " + feat.GetFID().ToString());
for (int iField = 0; iField < feat.GetFieldCount(); iField++)
{
FieldDefn fdef = def.GetFieldDefn(iField);
strInfomation += (fdef.GetNameRef() + " (" +
fdef.GetFieldTypeName(fdef.GetFieldType()) + ") = ");
if (feat.IsFieldSet(iField))
{
if (fdef.GetFieldType() == FieldType.OFTStringList)
{
string[] sList = feat.GetFieldAsStringList(iField);
foreach (string s in sList)
{
strInfomation += ("\"" + s + "\" ");
}
strInfomation += ("\n");
}
else if (fdef.GetFieldType() == FieldType.OFTIntegerList)
{
int count;
int[] iList = feat.GetFieldAsIntegerList(iField, out count);
for (int i = 0; i < count; i++)
{
strInfomation += (iList[i] + " ");
}
strInfomation += ("\n");
}
else if (fdef.GetFieldType() == FieldType.OFTRealList)
{
int count;
double[] iList = feat.GetFieldAsDoubleList(iField, out count);
for (int i = 0; i < count; i++)
{
strInfomation += (iList[i].ToString() + " ");
}
strInfomation += ("\n");
}
else
strInfomation += (feat.GetFieldAsString(iField));
}
else
strInfomation += ("(null)");
}
if (feat.GetStyleString() != null)
strInfomation += (" Style = " + feat.GetStyleString());
Geometry geom = feat.GetGeometryRef();
if (geom != null)
{
strInfomation += (" " + geom.GetGeometryName() +
"(" + geom.GetGeometryType() + ")");
Geometry sub_geom;
for (int i = 0; i < geom.GetGeometryCount(); i++)
{
sub_geom = geom.GetGeometryRef(i);
if (sub_geom != null)
{
strInfomation += (" subgeom" + i + ": " + sub_geom.GetGeometryName() +
"(" + sub_geom.GetGeometryType() + ")");
}
}
Envelope env = new Envelope();
geom.GetEnvelope(env);
strInfomation += (" ENVELOPE: " + env.MinX + "," + env.MaxX + "," +
env.MinY + "," + env.MaxY);
string geom_wkt;
geom.ExportToWkt(out geom_wkt);
strInfomation += (" " + geom_wkt);
}
strInfomation += ("\n");
return strInfomation;
}
}
4、写完读取代码，然后编写读取按钮的响应事件，具体代码如下：
private void buttonRasterRead_Click(object sender, EventArgs e)
{
string strRasterPath = textBoxRaster.Text;
if (strRasterPath == "")
{
MessageBox.Show("请先选择文件路径", "提示");
return;
}
string strInfomation = GDALReadFile.GetRasterInfo(strRasterPath);
richTextBoxInfo.Text = strInfomation;
}
private void buttonVectorRead_Click(object sender, EventArgs e)
{
string strVectorPath = textBoxVector.Text;
if (strVectorPath == "")
{
MessageBox.Show("请先选择文件路径", "提示");
return;
}
string strInfomation = OGRReadFile.GetVectorInfo(strVectorPath);
richTextBoxInfo.Text = strInfomation;
}
5、做完上面的步骤，你就可以编译了，编译很顺利，直接编译过去了（如果你不能编译过去，请查看错误并修改）。然后点击运行，选择一个栅格数据，然后点击读取，期待将图像信息写入下面的富文本框中，结果很悲剧的发现，出现了一个异常。群里很多人都遇到过这个异常，这个异常就是“Application error: “OSGeo.GDAL.GdalPINVOKE”的类型初始值设定项引发异常。”，截图如下：
下面就开始解决这个异常，按照下面的步骤进行解决：
首先：确定自己引用的GDAL库是正常的，检验正常的一个很方便的就是双击GDAL库中bin文件夹里面的exe，如果一闪而过，基本上就正常的。如果提示错误信息，比如，应用程序无法正常启动啥的，就先安装编译GDAL库的VS对应版本的C++分发库（也叫C++运行库，名字叫vcredist_x86.exe或者vcredist_x64.exe，注意还有SP1之分）。
第二：假设通过安装这个运行库，GDAL库可以正常启动了，接下来把GDAL库的C#版本里面的dll全部拷贝到C#程序编译的exe所在目录，比如我的是在【F:\Work\GDALTest\bin\Debug】，然后再次启动程序，看看还抛出异常不，如果不抛出异常，那么恭喜你，下面的不用看了（我的电脑到这步结束后就正常了）；如果还是抛出异常，不要着急，按照下面的步骤继续。
第三：通过上面的步骤还是不行的话，将整个工程的【配置管理器】中改成与GDAL库的版本一致，这里的版本指的是操作系统是32位还是64位，如果GDAL是32位的，那么在配置管理器中创建一个x86的平台，然后编译整个工程；如果GDAL版本是64位的，那么创建一个x64的平台进行编译。（这个步骤一般是会出现在使用32位的GDAL库在64位的系统上开发会用到）。
第四：如果你通过上面三个步骤还是没有解决的话，那我也不知道了……
最后截个图，看看输出的图像信息和矢量信息，初学者可以参考这个来读取栅格数据和矢量数据。程序的代码打包在我的CSDN资源里面，下载地址是：http://download.csdn.net/detail/liminlu0314/4653881
—————————————华丽的分割线 下面的修改于2012年10月17日—————————————
昨天忘记测试中文路径，发现果然中文路径不支持，具体说明参考下一篇博客。不想看的请在上面的打开数据的代码下面加下面的一句代码。至于原因查看下一篇博文。
[csharp] view plaincopyprint?
- OSGeo.GDAL.Gdal.SetConfigOption("GDAL_FILENAME_IS_UTF8", "YES");
