# demdiff

Compares rasters in ASC, BIL, TIF, IMG and RasterLAZ format and
reports differences.

If the input parameters are correct, the comparison result is reported as text output.

For identical files the output looks like:

rasters are identical. both have [n] value and [o] nodata cells.
done with '[p]'. total time [q] sec.
done with all files. total time for [r] files [s] sec.

For non-identical files the output looks like:

rasters are not identical. rasters have [m] different and [n] identical value cells. but both have [o] nodata cells
done with '[p]'. total time [q] sec.
done with all files. total time for [r] files [s] sec.

The text output can be parsed to get further information for automated processes.


## Warnings and Errors
If the input files or the arguments are not valid, an error output will be displayed:

    ERROR: cannot open raster1 with file name '...'.
The given filename was not found.

    ERROR: raster '...' has ... bands. not implemented.
Only files with 1 layers/bands are supported.

    ERROR: raster '...' has .. bits. not implemented.
Only files with 8,16 or 32 bits per pixel are supported.

    ERROR: raster '...' has no columns. skipping ...
    ERROR: raster '...' has no rows. skipping ... 
    ERROR: raster has no lower left x info
    ERROR: raster has no lower left y info
    ERROR: raster has no upper right x info
    ERROR: raster has no upper right y info
    ERROR: raster has no step x info
    ERROR: raster has no step y info
    ERROR: stepx_y of ... not supported
    ERROR: stepy_x of ... not supported
The input file should contain less then 1 data row or column.
Most likely the file is empty.

    ERROR: if more than two input rasters, they must all be in TIF, IMG, ASC, or BIL, not in LAZ format
When processing more than 2 input files they all have to be in the same format, and not LAZ files.
To compare LAZ files only an input of exact 2 files is supported.
    
    ERROR: raster '...' has ... bands. not implemented.
Only files with 1 color band (layers) are supported.
    
    ERROR: rasters have different ncols of ... and .... difference too big ...
    ERROR: rasters have different nrows of ... and .... difference too big ...
    WARNING: rasters have different nbits of ... and ...
The number of columns, rows and color bands of all files to compare has to be identical.


## Examples

    demdiff -i lake1.tif lake2.tif
    demdiff -i lake1.tif -i lake2.tif
Both commands compare the raster difference between file 'lake1.tif' and 'lake2.tif'.


## demdiff specific arguments

-i         : one or many input files to proceed
-cores [n] : process multiple inputs on [n] cores in parallel  

### Basics
-cpu64   : start 64 bit executable (instead of default 32 bit executable)  
-fail    : fail if license expired or invalid  
-gui     : start with files loaded into GUI  
-h       : print help output  
-help    : print help output  
-quiet   : nothing reported in console  
-v       : verbose output (print extra information)  
-verbose : verbose output (print extra information)  
-version : reports this tool's version number  
-vv      : very verbose output (print even more information)  


## License

Please send us an email to info@rapidlasso.de if you want to use the tool
commercially. You can carry out tests up to 3 mio points free of charge.
Please note that the unlicensed version may have output distortions 
(diagonal lines or added white noise to the coordinates).


## Support

To get more information about a tool, please visit 
[LAStools Google Group](http://groups.google.com/group/lastools/)
and enter the tool name in the search function.
You will find numerous examples of the corresponding tool.

For further support, please see
[rapidlasso service page](https://rapidlasso.de/service/)

Latest updates can be found at
https://rapidlasso.de/category/blog/releases/

If you have any suggestions, please let us know (info@rapidlasso.de).
We appreciate your feedback.