[R-sig-Geo] read error after mosaic_rasters

[Dijk, Michiel van]

Hi,

I am using mosaic_rasters from gdalUtils to combine different raster files. More specifically, I am using the 12 tiles that cover Southern Africa from the well-known Hansen et al. (2013) forest map (1.1) that can be downloaded here: http://earthenginepartners.appspot.com/science-2013-global-forest/download_v1.1.html. I am using the tree cover, forest gain and forest loss data. All is working fine for the forest gain and forest loss files but I receive an error when combing the tree cover files (which are the largest). 

Below you will find my code. Note that "tree_cover_files" is a vector that points towards the 12 tiles stored in a local folder. I am receiving the following error after some time:

Checking gdal_installation...
Scanning for GDAL installations...
Checking the gdalUtils_gdalPath option...
GDAL version 2.2.4
GDAL command being used: "C:\OSGeo4W64\bin\gdalbuildvrt.exe" -input_file_list "c:\Temp\RtmpkRd30l\file4687024480a.txt" "c:\Temp\RtmpkRd30l\file4684596162f.vrt" 
Checking gdal_installation...
Scanning for GDAL installations...
Checking the gdalUtils_gdalPath option...
GDAL version 2.2.4
GDAL command being used: "C:\OSGeo4W64\bin\gdal_translate.exe" -of "GTiff" "c:\Temp\RtmpkRd30l\file4684596162f.vrt" "P:/globiom/Projects/ISWEL/data/forest/combined_tiles/tree_cover.tif"
Input file size is 120000, 1600000...10...20...30...40...
ERROR 1: TIFFFillStrip:Read error at scanline 39921; got 3204 bytes, expected 10047
ERROR 1: TIFFReadEncodedStrip() failed.
ERROR 1: P:/globiom/Projects/ISWEL/data/forest/tree_cover/Hansen_GFC2014_treecover2000_10S_030E.tif, band 1: IReadBlock failed at X offset 0, Y offset 39922
ERROR 1: GetBlockRef failed at X block offset 0, Y block offset 39922

I understand that this might be thread error, related to how the files are read and intermediate vrt file is constructed (https://github.com/mapnik/node-mapnik/issues/437 ) and could be solved by setting "VRT_SHARED_SOURCE" to 0. I tried to do this using setCPLConfigOption("VRT_SHARED_SOURCE", "0") in R but still receive the same error. Is this really the way to solve this or is the file perhaps corrupt (unlikely as this dataset is used by many people - I also downloaded them twice)? I hope somebody can give me advice on how to make this work.

Many thanks,
Michiel



# prepare and save template for mosaic
e <- extent(20, 40, -20, -10)
template <- raster(e)
proj4string(template) <- CRS("+proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0") writeRaster(template, file = file.path(proj_path, "data/forest/combined_tiles/tree_cover.tif"), format="GTiff", overwrite = T)

# create mosaic
setCPLConfigOption("VRT_SHARED_SOURCE", "0") mosaic_rasters(gdalfile = tree_cover_files,
               dst_dataset = file.path(proj_path, "data/forest/combined_tiles/tree_cover.tif"), of="GTiff",
               verbose = T)
 


M. (Michiel) van Dijk, PhD
Research scholar | Ecosystems Services and Management (ESM) | International Institute for Applied Systems Analysis (IIASA) Senior researcher (out of office) | International Policy Division (IB) | Wageningen Economic Research