[Qgis-user] Model designer: Using value from a Number input as a parameter in a Raster Calculator expression

[Bo Victor Thomsen]

Hi list -

I can't find a method to use a Number input as a part of raster 
calculator expression in Model Designer.

Using QGIS version 3.42, in Model Designer I've:

  * Defined a Number Input field: /my_number/
  * Defined a Raster Layer selector : /my_raster/
  * Defined a Rater Calculator algorithm: /multiplication/

Now the crucial question: How to use the number from my number input in 
an expression inside Raster Calculator?

Ex. for a simple multiplication: /"A at 1" * parameter('my_number')/ or 
/"A at 1" * @my_number/

Whatever I do, I get an error message like this:

Algorithm 'model' starting…

Input parameters:

{ 'my_number' : 22, 'my_raster' : 
'D:/gis/gis_analyser/flis_volumen/normaliseret.tif', 'resultat' : 
'TEMPORARY_OUTPUT' }

Prepare algorithm: native:modelerrastercalc_1

Running multiplication [1/1]

Input Parameters:

{ CELL_SIZE: None, CREATION_OPTIONS: None, CRS: None, EXPRESSION: '"A at 1" 
* parameter(\'my_number\')', EXTENT: None, LAYERS: 
['D:/gis/gis_analyser/flis_volumen/normaliseret.tif'], OUTPUT: 
'TEMPORARY_OUTPUT' }

Error encountered while running multiplication: Error parsing formula.

Execution failed after 0.04 seconds


The error message indicate an error in my expression: /"A at 1" * 
parameter('my_number')/

So, how do i declare and use a Number Input inside a raster calculator 
expression ??

-- 
Med venlig hilsen / Best regards

Bo Victor Thomsen
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