.gdalWriteFormats: no visible global function definition for
  'gdalDrivers'
aiObsEx: no visible global function definition for 'readGDAL'
aiObsMe: no visible global function definition for 'readGDAL'
assessment: no visible global function definition for 'writeGDAL'
assessment: no visible global function definition for 'readGDAL'
batchPetHgsm: no visible global function definition for 'readGDAL'
batchPetHgsm: no visible global function definition for 'writeGDAL'
editr2dRfile : canReadRgf: no visible global function definition for
  'readGDAL'
monitoring: no visible global function definition for 'writeGDAL'
monitoring: no visible global function definition for 'readGDAL'
r2dRplot: no visible global function definition for 'readGDAL'
r2dRplot: no visible global function definition for 'spplot'
rasterStack: no visible global function definition for 'GDALinfo'
rasterStack: no visible global function definition for 'GDAL.open'
rasterStack: no visible global function definition for 'GDAL.close'
readr2dRfile: no visible global function definition for 'GDALinfo'
regStepRaster: no visible global function definition for 'GDALinfo'
regStepRaster: no visible global function definition for 'readGDAL'
regStepRaster: no visible global function definition for 'writeGDAL'
rgf.summarize: no visible global function definition for 'readGDAL'
rgf.summary: no visible global function definition for 'readGDAL'
rgf.summary: no visible global function definition for 'writeGDAL'
rgf.summary: no visible global function definition for 'GDALinfo'
rgf.summary: no visible global function definition for 'GDAL.open'
rgf.summary: no visible global function definition for 'GDAL.close'
rgf.summary: no visible global function definition for 'rowMedians'
rgf.summary: no visible global function definition for 'rowRanges'
rgf.summary: no visible global function definition for 'rowSds'
rgf.summary: no visible global function definition for 'rowVars'
rgf.summary: no visible global function definition for 'rowCounts'
rgf.when: no visible global function definition for 'readGDAL'
rueObsEx: no visible global function definition for 'readGDAL'
rueObsMe: no visible global function definition for 'readGDAL'
solarRad: no visible global function definition for 'is.projected'
solarRad: no visible global function definition for 'coordinates'
solarRad12M: no visible global function definition for 'writeGDAL'
summarize: no visible global function definition for 'writeGDAL'