Syntax for ImageMath expressions

[Agustin Lobo]

There is no documentation in

https://enmap-box.readthedocs.io/en/latest/usr_section/usr_manual/applications.html#imagemath

and just 2 examples in https://enmap-box.readthedocs.io/en/latest/usr_section/usr_cookbook/imagemath.html

Where could I find doc on the syntax that is needed?

My current need is just to calculate a layer of probability maxima from a multiband probability raster that is output from Predict Class Probability.

(Andreas Rabe kindly provided the way to calculate a mask for those pixels below a certain threshold in Issue #298, but we prefer to explore first the actual values to decide the threshold)

[Andreas Janz]

Unfortunately, we are missing a proper documentation for now. Regarding the NDVI example, enmap is a 3d numpy array, red and nir is a 2d sub-array of the enmap array.

As syntax, you can use any Numpy operators (+, -, /, *, …) or methodes, see https://numpy.org/doc/stable/reference/

In fact, the code snippet can be arbitrary Python code.

Sidenote: for debugging/testing, it may also be helpful to use print outputs, that will show up in the log widget: e.g. print(enmap.shape) will output the array dimensions of the EnMAP raster.

Hope that helps for now.

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[Agustin Lobo]

I understand documentation is a huge effort. Perhaps there could be an organized way for users to contribute examples.

[Andreas Janz]

Having an example section is a good idea. If you have an interesting example to begin with, just provide it here and I will add it to the docs.

[Andreas Janz]

Hi Agus,

we overhauled ImageMath, which is now called RasterMath. I still want to do a usage tutorial on ReadTheDocs soon. So stay tuned.

Regards
Andreas

[Andreas Janz]

resolves #475

→ <<cset dc110280f76b>>

[Andreas Janz]

https://enmap-box.readthedocs.io/en/latest/usr_section/usr_cookbook/raster_math.html