ENH: Inject `nodata` automatically in image metadata

app/otbExtractNormalVector.cxx

@@ -23,7 +23,7 @@
 #include "otbRepack.h"
 #include "otbPositionHelpers.h"
 
-#include "otbWrapperApplication.h"
+#include "otbApplicationWithNoData.h"
 #include "otbWrapperApplicationFactory.h"
 #include "otbFunctorImageFilter.h"
 #include "otbDEMHandler.h"
@@ -184,7 +184,7 @@ namespace Wrapper
  * \ingroup App???
  * \ingroup SARCalibrationExtended
  */
-class ExtractNormalVector : public Application
+class ExtractNormalVector : public ApplicationWithNoData
 {
 public:
   /** Standard class typedefs. */
@@ -226,10 +226,7 @@ private:
     AddParameter(ParameterType_OutputImage, "out",  "Image of normal vectors");
     SetParameterDescription("out",  "Image of normal vectors");
 
-    AddParameter(ParameterType_Float, "nodata", "NoData value");
-    SetParameterDescription("nodata", "DEM empty cells are filled with this value (optional -32768 by default)");
-    SetDefaultParameterFloat("nodata", -32768);
-    MandatoryOff("nodata");
+    DoInit_NoData();
 
     AddRAMParameter();
 
@@ -249,6 +246,7 @@ private:
 
     auto const nodata = GetParameterFloat("nodata");
     // std::cout << "nodata      => " << nodata << std::endl;
+    AddNodataInMetadata(nodata);
 
     auto const spacing = inputImage->GetSignedSpacing();
     FloatType const x_spacing = spacing[0];

app/otbSARComputeLocalIncidenceAngle.cxx

@@ -19,7 +19,7 @@
  */
 
 #include "otbSARComputeLocalIncidenceAngle.h"
-#include "otbWrapperApplication.h"
+#include "otbApplicationWithNoData.h"
 #include "otbWrapperApplicationFactory.h"
 
 // #define DOUBLES_EVERYWHERE
@@ -47,7 +47,7 @@ namespace Wrapper
  * \ingroup App???
  * \ingroup SARCalibrationExtended
  */
-class SARComputeLocalIncidenceAngle : public Application
+class SARComputeLocalIncidenceAngle : public ApplicationWithNoData
 {
 public:
   /** Standard class typedefs. */
@@ -109,6 +109,7 @@ private:
 #endif
     SetParameterDescription(k_out_sin, "Output image with abs(sin LIA)");
 
+    DoInit_NoData();
     AddParameter(ParameterType_Float, "nodata", "NoData value");
     SetParameterDescription("nodata", "DEM empty cells are filled with this value (optional -32768 by default)");
     SetDefaultParameterFloat("nodata", -32768);
@@ -139,6 +140,8 @@ private:
     // filter->ShallComputeLIASign(true);
 
     auto const nodata = GetParameterFloat("nodata");
+    AddNodataInMetadata(nodata, k_out_lia);
+    AddNodataInMetadata(nodata, k_out_sin);
     filter->SetNoData(nodata);
 
     SetParameterOutputImage(k_out_sin, filter->GetSinOutputImage());

include/otbApplicationWithNoData.h

+/*
+ * Copyright (C) 2005-2022 Centre National d'Etudes Spatiales (CNES)
+ *
+ * This file is part of Orfeo Toolbox
+ *
+ *     https://www.orfeo-toolbox.org/
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef otbApplicationWithNoData_h
+#define otbApplicationWithNoData_h
+
+#include "otbWrapperApplication.h"
+
+namespace otb
+{
+
+namespace Wrapper
+{
+
+/** Helper parent class for application that need to inject `&nodata=` in
+ * metadata.
+ *
+ * This class provides two services:
+ * - `DoInit_NoData()` meant to be called from `DoInit()` specialisation.
+ * - `AddNodataInMetadata()` meant to be called from `DoExecute()`
+ * specialisation.
+ *
+ * \author Luc Hermitte
+ * \copyright CS Group
+ * \ingroup App???
+ * \ingroup SARCalibrationExtended
+ */
+class ApplicationWithNoData : public Application
+{
+protected:
+  /**
+   * Registers a `-nodata` parameter.
+   */
+  void DoInit_NoData()
+  {
+    AddParameter(ParameterType_Float, "nodata", "NoData value");
+    SetParameterDescription("nodata", "DEM empty cells are filled with this value (optional -32768 by default)");
+    SetDefaultParameterFloat("nodata", -32768);
+    MandatoryOff("nodata");
+  }
+
+  /**
+   * Appends `&nodata={value}` at the end of the extended filename to force
+   * nodata to be added in metadata.
+   */
+  template <typename FloatType>
+  void AddNodataInMetadata(FloatType nodata, std::string const& out_param = "out")
+  {
+    std::string origin_FileName = GetParameterString(out_param);
+    std::ostringstream oss;
+    oss << origin_FileName;
+
+    // Check if FileName is extended (with the ? caracter)
+    // If not extended then override the FileName
+    auto const extension_start = origin_FileName.find('?');
+    if (extension_start == std::string::npos && !origin_FileName.empty())
+      oss << '?';
+    else
+    {
+      auto const nodata_start = origin_FileName.find("&nodata=");
+      if (nodata_start > extension_start)
+      {
+        // Let's trust the end-user. Even if the value doesn't match
+        otbLogMacro(Warning, <<"Trusting the nodata value required in extended filename. User specified " << nodata << " value won't be propagated in image metadata");
+        return ;
+      }
+    }
+    oss << "&nodata="<<nodata;
+    // Set the new FileName with extended options
+    SetParameterString(out_param, oss.str());
+  }
+};
+
+} //end namespace Wrapper
+} //end namespace otb
+
+#endif  // otbApplicationWithNoData_h