Hi,
I've been using the raster calculator lately and bumped into some
unexpected behaviour issues. They are hard to isolate but I will create
issues
One of the things is the creation of empty output grids, resulting in
raster layers with a range as described earlier in this thread:
([-1.79769e+308 to 1.79769e+308] instead of [0 1].
Somehow this was fixed after changing the locale (!) from NL back to EN.
I was using a model that contained raster calculators and a python
script running it.
No clue what it could be, maybe parameter names being translated (I hope
not!) or locale settings for decimal point/comma.
Also, the names of the model parameter are like
'qgis:rastercalculator_4:sub_calc_sqrt', still containing the
'rastercalculator_4' part which can not be found or changed using the
model editor.
Besides, I'm wondering why very common functionality is missing in the
raster calculator. I need abs() and max() functions and they don't
exist. Or am I missing something?
My solutions / work arounds using creative high school math are:
abs(a):
sqrt(a * a)
or
((a >= 0) * a) + ((a < 0) * -1 * a)
max(a, b):
((a >= b) * a) + ((a < b) * b)
Hope someone has a clue here. Guess I'm not the only one using vector
more often than raster...
Kind regards,
Raymond
On 21-03-19 17:19, shalum HOUENOU wrote:
OK then
Maixent,
*De : *matteo <mailto:matteo.ghe...@gmail.com>
*Envoyé le :*jeudi 21 mars 2019 17:14
*À : *shalum HOUENOU <mailto:shalumhoue...@gmail.com>
*Objet :*Re: [Qgis-user] how to fix the raster calculator
please answer to all (so you question is forwarded also to the user
mailing list)
I think then the raster calculator has a bug. Could you please report it?
https://issues.qgis.org/projects/qgis
or try to upgrade to QGIS 3.6
On 3/21/19 5:13 PM, shalum HOUENOU wrote:
>
>
> Yes I did, as it was mentionned in the training manual, section 8.3.7
>
> You have the link below :
>
>
https://docs.qgis.org/testing/en/docs/training_manual/rasters/terrain_analysis.html#moderate-fa-using-the-raster-calculator
>
>
>
> Maixent,
>
> *De : *matteo <mailto:matteo.ghe...@gmail.com>
> *Envoyé le :*jeudi 21 mars 2019 17:07
> *À : *shalum HOUENOU <mailto:shalumhoue...@gmail.com>;
> qgis-it-user-ow...@lists.osgeo.org
> <mailto:qgis-it-user-ow...@lists.osgeo.org>
> *Objet :*Re: [Qgis-user] how to fix the raster calculator
>
>
>
> Hi Maixent,
>
>
>
>
>
>> Indeed the boundaries of my output layer have Strange values
>
>> ([-1.79769e+308 to 1.79769e+308] instead of [0 1].
>
>>
>
>> Thus the output layer is invisible.
>
>>
>
>> I’ve already tried to change the max and the min value : The layer is
>
>> still invisible.
>
>>
>
>> What else could I do to fix it ? Any idea ?
>
>
>
> did you also set the reference layer in the algorithm UI?
>
>
>
> Matteo
>
>
>
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