Hello,
Just a heads up that the JS bindings for GDAL now have an /ExprTk.js
/plugin that comes with a stand-alone CLI alternative of /gdal_calc.py/
- /gdal_calc.js/.
While it is geared mostly towards the Node.js GDAL user and it lacks
many of the features of /gdal_calc.py/, it has a number of interesting
advantages for everyone who is using it for Earth sciences:
* As Earth sciences datasets always have blank spots, when working
with floating-point data types, it automatically converts /NoData/
values to /NaN/ before applying the expression and then /NaN/ to
/NoData/ when writing the output - so you don't have to handle it in
any special way - any expression that uses at least one /NaN/ input
automatically produces a /NaN/ output that gets written as /NoData/
- and this is smart enough to let pass an unused input in an if/else
statement
* It is fully multithreaded, each input band and each output band
run in separate threads, and the expression evaluation can even use
fork to evaluate series of pixels in separate threads - though this
requires very complex expressions to be of any use - /gdal_calc/ is
mostly I/O bound
* It supports both JS functions and /ExprTk.js/ expressions that
allow for natural if/else expressions and complex control blocks
* It can write multi-band files applying a separate expression
on each band
https://www.npmjs.com/package/gdal-exprtk
--
Momtchil Momtchev<[email protected]>
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