support selection of dimension for writers.gdal #1325

doc/stages/writers.gdal.rst

@@ -20,13 +20,10 @@ potentially contributes to the raster's value.
     it is possible that some points will not be considered at all, including
     those that may be within the bounds of the raster cell.
 
-The GDAL writer creates rasters using the data in the 'Z' dimension of the
-points.  In a :ref:`pipeline_command` one can precede the GDAL writer with
-the ferry filter (:ref:`filters.ferry`) in order to copy data from some
-other dimension to the 'Z' dimension if desired.
-
-The writer will creates up to six rasters based on different statistics in
-the output dataset.  The order of the layers in the dataset is as follows:
+The GDAL writer creates rasters using the data specified in the ``dimension``
+option (defaults to `Z`).The writer will creates up to six rasters based on
+different statistics in the output dataset.  The order of the layers in the
+dataset is as follows:
 
 min
     Give the cell the minimum value of all points within the given radius.
@@ -125,3 +122,5 @@ window_size
     the fallback interpolation method.  See the stage description for more
     information. [Default: 0]
 
+dimension
+  A dimension name to use for the interpolation. [Default: ``Z``]

io/gdal/GDALWriter.cpp

@@ -71,6 +71,7 @@ void GDALWriter::addArgs(ProgramArgs& args)
     args.add("window_size", "Cell distance for fallback interpolation",
         m_windowSize);
     args.add("nodata", "No data value", m_noData, -9999.0);
+    args.add("dimension", "Dimension to use", m_interpDimString, "Z");
 }
 
 
@@ -105,6 +106,10 @@ void GDALWriter::initialize()
     }
 
     gdal::registerDrivers();
+
+    m_interpDim = Dimension::id(m_interpDimString);
+    if (m_interpDim == Dimension::Id::Unknown)
+        throw pdal_error("Dimension name is not known!");
 }
 
 void GDALWriter::ready(PointTableRef table)
@@ -134,7 +139,7 @@ void GDALWriter::write(const PointViewPtr view)
             m_bounds.minx;
         double y = view->getFieldAs<double>(Dimension::Id::Y, idx) -
             m_bounds.miny;
-        double z = view->getFieldAs<double>(Dimension::Id::Z, idx);
+        double z = view->getFieldAs<double>(m_interpDim, idx);
 
         m_grid->addPoint(x, y, z);
    }

io/gdal/GDALWriter.hpp

@@ -73,6 +73,9 @@ class PDAL_DLL GDALWriter : public Writer
     int m_outputTypes;
     GDALGridPtr m_grid;
     double m_noData;
+    Dimension::Id m_interpDim;
+    std::string m_interpDimString;
+
 };
 
 }