default to using the file's SRS info, not the tile index column, unle…

…ss the user overrides with the explicit 'srs_column' option (#3102)

* default to using the file's SRS info, not the tile index column, unless the user overrides with the explicit 'srs_column' option

* compilation fixes

io/TIndexReader.cpp

@@ -62,10 +62,8 @@ TIndexReader::FieldIndexes TIndexReader::getFields()
     if (indexes.m_filename < 0)
         throwError("Unable to find field '" + m_tileIndexColumnName +
             "' in file '" + m_filename + "'.");
-    indexes.m_srs = OGR_FD_GetFieldIndex(fDefn, m_srsColumnName.c_str());
-    if (indexes.m_srs < 0)
-        throwError("Unable to find field '" + m_srsColumnName + "' in file '" +
-            m_filename + "'.");
+    if (m_srsColumnName.size())
+        indexes.m_srs = OGR_FD_GetFieldIndex(fDefn, m_srsColumnName.c_str());
 
     indexes.m_ctime = OGR_FD_GetFieldIndex(fDefn, "created");
     indexes.m_mtime = OGR_FD_GetFieldIndex(fDefn, "modified");
@@ -90,8 +88,12 @@ std::vector<TIndexReader::FileInfo> TIndexReader::getFiles()
         FileInfo fileInfo;
         fileInfo.m_filename =
             OGR_F_GetFieldAsString(feature, indexes.m_filename);
-        fileInfo.m_srs =
-            OGR_F_GetFieldAsString(feature, indexes.m_srs);
+
+        if (m_srsColumnName.size())
+        {
+            fileInfo.m_srs =
+                OGR_F_GetFieldAsString(feature, indexes.m_srs);
+        }
         output.push_back(fileInfo);
 
         OGR_F_Destroy(feature);
@@ -105,7 +107,7 @@ void TIndexReader::addArgs(ProgramArgs& args)
 {
     args.add("lyr_name", "OGR layer name from which to read tile index layer",
         m_layerName, "pdal");
-    args.add("srs_column", "Column to use for SRS", m_srsColumnName, "srs");
+    args.add("srs_column", "Column to use to override a file's SRS", m_srsColumnName, "");
     args.add("tindex_name", "OGR column name from which to read tile "
         "index location", m_tileIndexColumnName, "location");
     args.add("sql", "OGR-compatible SQL statement for querying tile "
@@ -226,17 +228,19 @@ void TIndexReader::initialize()
         reader->setOptions(readerOptions);
         Stage *premerge = reader;
 
-        if (m_tgtSrsString != f.m_srs &&
-            (m_tgtSrsString.size() && f.m_srs.size()))
+        if (m_tgtSrsString.size() )
         {
             Stage *repro = m_factory.createStage("filters.reprojection");
             repro->setInput(*reader);
             Options reproOptions;
             reproOptions.add("out_srs", m_tgtSrsString);
-            reproOptions.add("in_srs", f.m_srs);
-            log()->get(LogLevel::Debug2) << "Repro = "
-                                         << m_tgtSrsString << "/"
-                                         << f.m_srs << "!\n";
+            if (m_srsColumnName.size())
+            {
+                reproOptions.add("in_srs", f.m_srs);
+                log()->get(LogLevel::Debug2) << "Repro = "
+                                             << m_tgtSrsString << "/"
+                                             << f.m_srs << "!\n";
+            }
             repro->setOptions(reproOptions);
             premerge = repro;
         }