make filters.hag_dem streamable, improve docs

doc/stages/filters.hag_dem.rst

@@ -3,17 +3,6 @@
 filters.hag_dem
 ===============================================================================
 
- loads a GDAL readable raster
- specifying the DEM to calculate ``HeightAboveGround`` from. The ``Z`` value
- of each point is compared against the value at the corresponding X,Y point in
- the DEM raster.
-
- If `respect_ground_classification`_ is set, any points classified as ground will
- have their ``HeightAboveGround`` value set to 0 regardless of the raster.
-
- Any points that do not have a corresponding value in the raster DEM will not have
- a ``HeightAboveGround`` value set.
-
 The **Height Above Ground (HAG) Digital Elevation Model (DEM) filter** loads
 a GDAL-readable raster image specifying the DEM. The ``Z`` value of each point
 in the input is compared against the value at the corresponding X,Y location
@@ -27,6 +16,8 @@ opposed to its raw elevation value.
 
 .. embed::
 
+.. streamable::
+
 Example #1
 ----------
 
@@ -39,7 +30,8 @@ and a DEM generated from it
 
 ::
   
-  # pdal translate autzen.laz autzen-dem.tiff filters.smrf
+  # pdal translate autzen.laz autzen-dem.tiff filters.smrf \
+      --writers.gdal.resolution=1
 
 we execute the following pipeline
 

doc/stages/filters.rst

@@ -43,6 +43,7 @@ invalidate an existing KD-tree.
    filters.elm
    filters.ferry
    filters.hag
+   filters.hag_dem
    filters.info
    filters.lof
    filters.miniball
@@ -97,6 +98,9 @@ invalidate an existing KD-tree.
     Compute pointwise height above ground estimate. Requires points to be
     classified as ground/non-ground prior to estimating.
 
+:ref:`filters.hag_dem`
+    Compute pointwise height above GDAL-readable DEM raster.
+
 :ref:`filters.lof`
     Compute pointwise Local Outlier Factor (along with K-Distance and Local
     Reachability Distance).

filters/HAGDEMFilter.cpp

@@ -34,13 +34,8 @@
 
 #include "HAGDEMFilter.hpp"
 
-#include <pdal/KDIndex.hpp>
 #include <pdal/GDALUtils.hpp>
 
-#include <string>
-#include <vector>
-#include <cmath>
-
 namespace pdal
 {
 
@@ -96,33 +91,40 @@ void HAGDEMFilter::prepared(PointTableRef table)
 }
 
 void HAGDEMFilter::filter(PointView& view)
+{
+    PointRef point(view, 0);
+    for (PointId i = 0; i < view.size(); ++i)
+    {
+      point.setPointId(i);
+      processOne(point);
+    }
+}
+
+bool HAGDEMFilter::processOne(PointRef& point)
 {
     using namespace pdal::Dimension;
     static std::vector<double> data;
 
-    for (PointId i = 0; i < view.size(); ++i)
+    // If "zero_ground" option is set, all ground points get HAG of 0
+    if (m_zeroGround && point.getFieldAs<uint8_t>(Id::Classification) == ClassLabel::Ground)
     {
+        point.setField(Id::HeightAboveGround, 0);
+    }
+    else
+    {
+        double x = point.getFieldAs<double>(Id::X);
+        double y = point.getFieldAs<double>(Id::Y);
+        double z = point.getFieldAs<double>(Id::Z);
 
-        // If "zero_ground" option is set, all ground points get HAG of 0
-        if (m_zeroGround && view.getFieldAs<uint8_t>(Id::Classification, i) == ClassLabel::Ground)
+        // If raster has a point at X, Y of pointcloud point, use it. Otherwise the HAG
+        // value is not set.
+        if (m_raster->read(x, y, data) == gdal::GDALError::None)
         {
-            view.setField(Id::HeightAboveGround, i, 0);
+            double hag = z - data[m_band - 1];
+            point.setField(Dimension::Id::HeightAboveGround, hag);
         }
-        else
-        {
-          double x = view.getFieldAs<double>(Id::X, i);
-          double y = view.getFieldAs<double>(Id::Y, i);
-          double z = view.getFieldAs<double>(Id::Z, i);
-
-          // If raster has a point at X, Y of pointcloud point, use it. Otherwise the HAG
-          // value is not set.
-          if (m_raster->read(x, y, data) == gdal::GDALError::None)
-          {
-              double hag = z - data[m_band - 1];
-              view.setField(Dimension::Id::HeightAboveGround, i, hag);
-          }
-       }
     }
+    return true;
 }
 
 } // namespace pdal

filters/HAGDEMFilter.hpp

@@ -35,6 +35,7 @@
 #pragma once
 
 #include <pdal/Filter.hpp>
+#include <pdal/Streamable.hpp>
 
 #include <cstdint>
 #include <memory>
@@ -48,7 +49,7 @@ class Options;
 class PointLayout;
 class PointView;
 
-class PDAL_DLL HAGDEMFilter : public Filter
+class PDAL_DLL HAGDEMFilter : public Filter, public Streamable
 {
 public:
     HAGDEMFilter();
@@ -63,6 +64,7 @@ class PDAL_DLL HAGDEMFilter : public Filter
     virtual void prepared(PointTableRef table);
     virtual void ready(PointTableRef table);
     virtual void filter(PointView& view);
+    virtual bool processOne(PointRef& point);
 
     std::unique_ptr<gdal::Raster> m_raster;
     std::string m_rasterName;