ENH: Adding a complex derived dataset to allow for on-the-fly computa…

…tion of amplitude while reading

gdal/frmts/cderived/GNUmakefile

@@ -0,0 +1,11 @@
+
+include ../../GDALmake.opt
+
+OBJ	=	cderiveddataset.o
+
+default:	$(OBJ:.o=.$(OBJ_EXT))
+
+clean:
+	rm -f *.o $(O_OBJ)
+
+install-obj:	$(O_OBJ:.o=.$(OBJ_EXT))

gdal/frmts/cderived/cderiveddataset.cpp

@@ -0,0 +1,195 @@
+#include "../vrt/vrtdataset.h"
+#include "gdal_pam.h"
+#include "gdal_proxy.h"
+
+#include <iostream>
+
+CPLErr ModulePixelFunc(void **papoSources, int nSources, void *pData,
+                       int nXSize, int nYSize,
+                       GDALDataType eSrcType, GDALDataType eBufType,
+                       int nPixelSpace, int nLineSpace)
+{
+    int ii, iLine, iCol;
+    double dfPixVal;
+
+    /* ---- Init ---- */
+    if (nSources != 1) return CE_Failure;
+
+    if (GDALDataTypeIsComplex( eSrcType ))
+    {
+         double dfReal, dfImag;
+        void *pReal = papoSources[0];
+        void *pImag = ((GByte *)papoSources[0])
+                    + GDALGetDataTypeSize( eSrcType ) / 8 / 2;
+
+        /* ---- Set pixels ---- */
+        for( iLine = 0, ii = 0; iLine < nYSize; ++iLine ) {
+            for( iCol = 0; iCol < nXSize; ++iCol, ++ii ) {
+
+                /* Source raster pixels may be obtained with SRCVAL macro */
+                dfReal = SRCVAL(pReal, eSrcType, ii);
+                dfImag = SRCVAL(pImag, eSrcType, ii);
+
+                dfPixVal = sqrt( dfReal * dfReal + dfImag * dfImag );
+
+                GDALCopyWords(&dfPixVal, GDT_Float64, 0,
+                              ((GByte *)pData) + nLineSpace * iLine +
+                              iCol * nPixelSpace, eBufType, nPixelSpace, 1);
+            }
+        }
+    } else {
+        /* ---- Set pixels ---- */
+        for( iLine = 0, ii = 0; iLine < nYSize; ++iLine ) {
+            for( iCol = 0; iCol < nXSize; ++iCol, ++ii ) {
+
+                /* Source raster pixels may be obtained with SRCVAL macro */
+                dfPixVal = fabs(SRCVAL(papoSources[0], eSrcType, ii));
+
+                GDALCopyWords(&dfPixVal, GDT_Float64, 0,
+                              ((GByte *)pData) + nLineSpace * iLine +
+                              iCol * nPixelSpace, eBufType, nPixelSpace, 1);
+            }
+        }
+    }
+
+    /* ---- Return success ---- */
+    return CE_None;
+} /* ModulePixelFunc */
+
+
+class ComplexDerivedDatasetContainer: public GDALPamDataset
+{
+    public:
+        ComplexDerivedDatasetContainer() {}
+};
+
+
+class ComplexDerivedDataset : public VRTDataset
+{
+  public:
+  ComplexDerivedDataset(int nXSize, int nYSize);
+  ~ComplexDerivedDataset();
+
+    static GDALDataset *Open( GDALOpenInfo * );
+    static int          Identify( GDALOpenInfo * );
+};
+
+
+ComplexDerivedDataset::ComplexDerivedDataset(int nXSize, int nYSize) : VRTDataset(nXSize,nYSize)
+{
+  poDriver = NULL;
+  SetWritable(FALSE);
+}
+
+ComplexDerivedDataset::~ComplexDerivedDataset()
+{
+}
+
+int ComplexDerivedDataset::Identify(GDALOpenInfo * poOpenInfo)
+{
+  if(STARTS_WITH_CI(poOpenInfo->pszFilename, "DERIVED_SUBDATASET:COMPLEX_AMPLITUDE:"))
+    return TRUE;
+
+  return FALSE;
+}
+
+GDALDataset * ComplexDerivedDataset::Open(GDALOpenInfo * poOpenInfo)
+{
+  if( !Identify(poOpenInfo) )
+    {
+    return NULL;
+    }
+
+  /* Try to open original dataset */
+  CPLString filename(poOpenInfo->pszFilename);
+
+  // TODO: check starts with
+
+  /* DERIVED_SUBDATASET should be first domain */
+  size_t dsds_pos = filename.find("DERIVED_SUBDATASET:");
+
+  if (dsds_pos == std::string::npos)
+    {
+    /* Unable to Open in this case */
+    return NULL;
+    }
+
+  /* DERIVED_SUBDATASET should be first domain */
+  size_t alg_pos = filename.find(":",dsds_pos+20);
+  if (alg_pos == std::string::npos)
+    {
+    /* Unable to Open in this case */
+    return NULL;
+    }
+
+  VRTDerivedRasterBand::AddPixelFunction("mod",ModulePixelFunc);
+
+  CPLString odFilename = filename.substr(alg_pos+1,filename.size() - alg_pos);
+
+  GDALDataset * poTmpDS = (GDALDataset*)GDALOpen(odFilename, GA_ReadOnly);
+
+   if( poTmpDS == NULL )
+     return NULL;
+
+   int nbBands = poTmpDS->GetRasterCount();
+
+   int nRows = poTmpDS->GetRasterYSize();
+   int nCols = poTmpDS->GetRasterXSize();
+
+   ComplexDerivedDataset * poDS = new ComplexDerivedDataset(nCols,nRows);
+
+   // Transfer metadata
+   poDS->SetMetadata(poTmpDS->GetMetadata());
+
+   for(int nBand = 1; nBand <= nbBands; ++nBand)
+     {
+
+
+     VRTDerivedRasterBand * poBand;    
+
+     GDALDataType type  = GDT_Float64;
+
+     poBand = new VRTDerivedRasterBand(poDS,nBand,type,nCols,nRows);
+     poBand->SetPixelFunctionName("mod");
+     poBand->SetSourceTransferType(poTmpDS->GetRasterBand(nBand)->GetRasterDataType());
+     poDS->SetBand(nBand,poBand);
+
+     GDALProxyPoolDataset* proxyDS;
+     proxyDS = new GDALProxyPoolDataset(         odFilename,
+                                                 poDS->nRasterXSize,
+                                                 poDS->nRasterYSize,
+                                                 GA_ReadOnly,
+                                                 TRUE);
+     proxyDS->AddSrcBandDescription(poTmpDS->GetRasterBand(nBand)->GetRasterDataType(), 128, 128);
+
+     poBand->AddComplexSource(proxyDS->GetRasterBand(nBand),0,0,nCols,nRows,0,0,nCols,nRows);
+     proxyDS->Dereference();     
+     }
+
+   // TODO: do this earlier ?
+   delete poTmpDS;
+
+   return poDS;
+}
+
+void GDALRegister_ComplexDerived()
+{
+    if( GDALGetDriverByName( "COMPLEXDERIVED" ) != NULL )
+        return;
+
+    GDALDriver *poDriver = new GDALDriver();
+
+    poDriver->SetDescription( "COMPLEXDERIVED" );
+#ifdef GDAL_DCAP_RASTER
+    poDriver->SetMetadataItem( GDAL_DCAP_RASTER, "YES" );
+#endif
+    poDriver->SetMetadataItem( GDAL_DCAP_VIRTUALIO, "YES" );
+    poDriver->SetMetadataItem( GDAL_DMD_LONGNAME, "Complex derived bands" );
+    poDriver->SetMetadataItem( GDAL_DMD_HELPTOPIC, "frmt_sentinel2.html" );
+    poDriver->SetMetadataItem( GDAL_DMD_SUBDATASETS, "YES" );
+
+    poDriver->pfnOpen = ComplexDerivedDataset::Open;
+    poDriver->pfnIdentify = ComplexDerivedDataset::Identify;
+
+    GetGDALDriverManager()->RegisterDriver( poDriver );
+}

gdal/frmts/gdalallregister.cpp

@@ -68,6 +68,7 @@ void CPL_STDCALL GDALAllRegister()
 
 #ifdef FRMT_vrt
     GDALRegister_VRT();
+    GDALRegister_ComplexDerived();
 #endif
 
 #ifdef FRMT_gtiff

gdal/gcore/gdal_frmts.h

@@ -187,6 +187,7 @@ void CPL_DLL GDALRegister_SAFE(void);
 void CPL_DLL GDALRegister_SENTINEL2(void);
 void CPL_DLL GDALRegister_mrf(void);
 void CPL_DLL GDALRegister_RRASTER(void);
+void CPL_DLL GDALRegister_ComplexDerived(void);
 CPL_C_END
 
 #endif /* ndef GDAL_FRMTS_H_INCLUDED */