Hi Pedro,
I did the same for 5 pixels in the test raster I shared with you yesterday.
The different seems to be a little bit greater.
See the attached sheet.
I don't know if the version of saga, 2.3.1 the mine vs 2.3.2 the yours could
generate this error,
or if the problem is in qgis process model.
E.
________________________________
Da: Pedro Venâncio <pedrongvenan...@gmail.com>
Inviato: mercoledì 31 maggio 2017 22:16
A: Eugenio Trumpy
Cc: qgis-user; qgis-developer
Oggetto: Re: [Qgis-user] Wrong result with Saga Raster calculator
Hi Eugenio,
I've created a sample processing model (attached), that works ok, except a
small error in the result (decimals).
For instance:
Raster ID Pixel value
Z_top_res a 1202,03510276
t_top_res b 53,6123428345
topo c1 -182,584899902
SAGA Result 1 c 15,1783676147
SAGA Result 2 d 31,9437332153 Diff
Expected Result 1
15,1783679504 0,000000335741
Expected Result 2
31,9740872222 0,0303540069
Formula
1 ifelse(c1>0,-(0.0065*c1-16),(0.0045*c1+16))
2 ifelse(a<500,0,((b-c)/a)*1000)
Using SAGA GUI there is no error.
Could this be because of some roundings in the input / output? (I'm sending for
the developer's list also).
Thanks!
Best regards,
Pedro Venâncio
2017-05-31 10:56 GMT+01:00 Eugenio Trumpy
<frippe12...@hotmail.com<mailto:frippe12...@hotmail.com>>:
Hi Pedro,
thank you very much to have tested the computation with my test data!
You are right, I checked again the computation and actually it works.
However, I was using Saga raster calculation in a processing modeler, and one
of the layer I share with you
is the resulting from a previous computation.
In other word the raster layer c=temp_recal.tif comes from a previous
computation (raster calculator):
ifelse(a>0,-(0.0065*a-16),(0.0045*a+16))
where a is the layer attached, and hence c of the previous formula is the
resulting of this first computation.
E.
________________________________
Da: Pedro Venâncio <pedrongvenan...@gmail.com<mailto:pedrongvenan...@gmail.com>>
Inviato: mercoledì 31 maggio 2017 11:37
A: frippe12573; qgis-user
Oggetto: Re: [Qgis-user] Wrong result with Saga Raster calculator
Hi Eugenio,
The result with SAGA Raster Calculator seems ok here, on QGIS 2.18.9, SAGA
2.3.2, both from OSGeo4W64 (result attached).
Z_top_res.tif have values from 724.403 to 1423.553, and so, the first condition
is never true. Then, it always make ((b-c)/a)*1000, and the result seems ok to
me.
Pedro
2017-05-31 10:19 GMT+01:00 frippe12573
<frippe12...@hotmail.com<mailto:frippe12...@hotmail.com>>:
Hi Paolo,
the raster have the same size and origin.
The pixels are precisely overlapped.
I tried also r.mapcalc, but I got a worst result.
Here the output of the log:
https://pastebin.com/jNyyzHgf
E.
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