Handle netcdf with defined lat/lon but NaN in the z val which can happen due to reprojecting nc files

Author: Chrismarsh

src/metdata.cpp

@@ -114,6 +114,8 @@ void metdata::load_from_netcdf(const std::string& path,std::map<std::string, boo
         // #pragma omp parallel for
         // hangs, unclear why, critical sections around the json and gdal calls
         // don't seem to help. Probably _dD_tree is not thread safe
+
+        int skipped = 0; // keep track of how many we skipped due to nans
         for (size_t y = 0; y < _nc->get_ysize(); y++)
         {
             for (size_t x = 0; x < _nc->get_xsize(); x++)
@@ -130,23 +132,16 @@ void metdata::load_from_netcdf(const std::string& path,std::map<std::string, boo
 
                 // Some Netcdf files have NaN grid squares, For these cases we will just insert a nullptr station and
                 // don't add the station to the dD list which is the only way it ever gets to modules
-                if ( std::isnan(latitude) &&
-                    std::isnan(longitude) )
+                if ( std::isnan(latitude) ||
+                    std::isnan(longitude) ||
+                    std::isnan(z))
                 {
                     _stations.at(index) = nullptr;
+                    ++skipped;
                     continue;
                 }
 
 
-
-                if( std::isnan(z))
-                {
-                    CHM_THROW_EXCEPTION(forcing_error,
-                                        "Elevation for x,y=" + std::to_string(x) + ","+ std::to_string(y)+
-                                            " is NaN. Regardless of the timestep the model is started from, it looks for timestep = 0 to define the elevations. Ensure it is defined then.");
-                }
-
-
                 std::string station_name = std::to_string(index); // these don't really have names
 
                 //need to convert the input lat/long into the coordinate system our mesh is in
@@ -176,6 +171,14 @@ void metdata::load_from_netcdf(const std::string& path,std::map<std::string, boo
             }
         }
 
+        if( skipped == _nstations)
+        {
+            CHM_THROW_EXCEPTION(forcing_error,
+                                "All forcing grid cells were skipped due to being NaN values. Elevation and lat/lon,"
+                                " regardless of the timestep the model is started from, are defined from timestep = 0 "
+                                ". Ensure it is defined then.");
+        }
+
     } catch(netCDF::exceptions::NcException& e)
     {
         OGRCoordinateTransformation::DestroyCT(coordTrans);