Raster statistics appear to be copied and not updated about taudem

[dtarb]

This is true and is an issue. A short term fix would be to fiddle in the tiffio library, but I am loath to do that as tiffio has significant limitations and is at a dead end. A longer term fix that we are working on is to replace the use of tiffio library with the GDAL library. Then hopefully this and other I/O issues will be resolved. I am hoping that we can get to this in the next few months. Until then the workaround of computing statistics afterwards will have to suffice, unless there is someone who can get to the implementation of GDAL as an IO library before us.

[mwtoews]

Great to hear plans to use GDAL; GDALRasterBand::ComputeStatistics is the function to do this.

[dtarb]

@nazmussazib please check if the GDAL implementation resolves this. Please evaluate whether GDALRasterBand::ComputeStatistics should be performed on each raster output by TauDEM and implement if necessary. The current strategy is

1. Python script is called by ArcGIS toolbox tools.
2. Python script calls TauDEM C++ command line function.
3. Python script runs compute statistics on result.

The limitation of this is that statistics are only evaluated automatically in the ArcGIS implementation.

Including ComputeStatistics in the C++ command line functions would make statistics available to all deployments, not only ArcGIS, however there may be a computational hit, and the parallel large grid performance is unknown and needs to be evaluated.

[dtarb]

Closing. GDAL implementation will have resolved the incorrect statistics from tiffio. Our C++ code does not compute statistics. It is unclear whether GDAL does this internally, but even if not I am loathe to fiddle without a pressing concern. There is always the option to run a separate GDAL function to compute statistics, and one could argue this is better anyway as not all codes need to be burdened by statistics evaluation.

[mwtoews]

GDAL does not automatically calculate statistics, and I think it's best to leave that to the users to figure out.