writers.copc: fix legacy point/return counts

According to the LAS 1.4 r15 spec (§2.4)
> Legacy Number of Point Records
> This field contains the total number of point records within the file
> if the file is maintaining legacy compatibility, the number of points
> is no greater than UINT32_MAX, and the Point Data Record Format is
> less than 6. Otherwise, it must be set to zero.

> Legacy Number of Points by Return
> These fields contain an array of the total point records per return if
> the file is maintaining legacy compatibility, the number of points is
> no greater than UINT32_MAX, and the Point Data Record Format is less
> than 6. Otherwise, each member of the array must be set to zero.

All COPC files are LAS1.4 & PDRF>=6, so alway set the legacy point
count and return count fields to zero to match the spec. PDAL#2235

* extend the LasTester class to access LasReader internal headers
* add the COPC tests to the issue2235 LAS test case

io/LasReader.cpp

@@ -138,6 +138,11 @@ const LasHeader& LasReader::header() const
     return d->apiHeader;
 }
 
+const las::Header& LasReader::lasHeader() const
+{
+    return d->header;
+}
+
 uint64_t LasReader::vlrData(const std::string& userId, uint16_t recordId, char const * & data)
 {
     const las::Vlr *vlr = las::findVlr(userId, recordId, d->vlrs);

io/LasReader.hpp

@@ -60,6 +60,8 @@ class LasHeader;
 
 class PDAL_DLL LasReader : public Reader, public Streamable
 {
+    friend class LasTester;
+
 protected:
     class LasStreamIf
     {
@@ -121,6 +123,8 @@ class PDAL_DLL LasReader : public Reader, public Streamable
     void loadExtraDims(LeExtractor& istream, PointRef& data);
     point_count_t readFileBlock(std::vector<char>& buf, point_count_t maxPoints);
 
+    const las::Header& lasHeader() const;
+
     struct Options;
     struct Private;
     std::unique_ptr<Private> d;

io/private/copcwriter/Output.cpp

@@ -80,6 +80,10 @@ Output::Output(const BaseInfo& b) : b(b)
     m_header.minz = b.stats[(int)stats::Index::Z].minimum();
     m_header.maxz = b.stats[(int)stats::Index::Z].maximum();
 
+    // legacy point counts are all zero, since COPC is LAS 1.4 only.
+    std::fill(std::begin(m_header.points_by_return), std::end(m_header.points_by_return), 0);
+    m_header.point_count = 0;
+
     for (int i = 1; i <= 15; ++i)
     {
         point_count_t count = 0;
@@ -91,18 +95,8 @@ Output::Output(const BaseInfo& b) : b(b)
         {}
 
         m_header.points_by_return_14[i - 1] = count;
-        if (i <= 5)
-        {
-            if (m_header.points_by_return_14[i] <= (std::numeric_limits<uint32_t>::max)())
-                m_header.points_by_return[i - 1] = m_header.points_by_return_14[i - 1];
-            else
-                m_header.points_by_return[i - 1] = 0;
-        }
     }
 
-    if (m_header.point_count_14 > (std::numeric_limits<uint32_t>::max)())
-        m_header.point_count = 0;
-
     // Note that only these VLRs go in the standard VLR area. The rest are written as
     // extended VLRs.
     setupVlrs();
@@ -231,7 +225,6 @@ uint64_t Output::newChunk(const VoxelKey& key, int32_t size, int32_t count)
     m_pointPos += size;
     assert(count <= (std::numeric_limits<int32_t>::max)() && count >= 0);
     m_chunkTable.push_back({(uint64_t)count, (uint64_t)size});
-    m_header.point_count += count;
     m_header.point_count_14 += count;
     m_hierarchy[key] = { chunkStart, size, count };
     return chunkStart;

test/unit/io/LasWriterTest.cpp

@@ -43,6 +43,7 @@
 #include <pdal/util/Algorithm.hpp>
 #include <pdal/util/FileUtils.hpp>
 #include <io/BufferReader.hpp>
+#include <io/CopcWriter.hpp>
 #include <io/LasHeader.hpp>
 #include <io/LasReader.hpp>
 #include <io/LasWriter.hpp>
@@ -66,6 +67,8 @@ class LasTester
 public:
     const las::Header& header(LasWriter& w)
         { return w.header(); }
+    const las::Header& header(LasReader& r)
+        { return r.lasHeader(); }
     SpatialReference srs(LasWriter& w)
         { return w.m_srs; }
     void addVlr(LasWriter& w, const std::string& userId, uint16_t recordId,
@@ -1989,4 +1992,39 @@ TEST(LasWriterTest, issue2235)
                 EXPECT_NE(h46.ePointsByReturn[i], 0);
         }
     }
+
+    // test for COPC too
+    {
+        Options copcWriterOps;
+        copcWriterOps.add("filename", Support::temppath("out_4_6.copc.laz"));
+
+        CopcWriter copcWriter;
+        copcWriter.setInput(reader);
+        copcWriter.setOptions(copcWriterOps);
+
+        PointTable tableCopc;
+        copcWriter.prepare(tableCopc);
+        copcWriter.execute(tableCopc);
+
+        Options copcReaderOpts;
+        copcReaderOpts.add("filename", Support::temppath("out_4_6.copc.laz"));
+
+        LasReader readerCopc;
+        readerCopc.setOptions(copcReaderOpts);
+
+        PointTable tableCopcR;
+        readerCopc.prepare(tableCopcR);
+
+        const las::Header& headerCopc = tester.header(readerCopc);
+
+        EXPECT_EQ(headerCopc.legacyPointCount, 0);
+        EXPECT_NE(headerCopc.pointCount(), 0);
+
+        for (int i=0; i<headerCopc.LegacyReturnCount; i++)
+        {
+            EXPECT_EQ(headerCopc.legacyPointsByReturn[i], 0);
+            if (i < returnsWithPoints)
+                EXPECT_NE(headerCopc.ePointsByReturn[i], 0);
+        }
+    }
 }