Hi Andreas,

Thanks for the fix.

I tried with your solution <Scale> and <Offset> with a simple source but
it didn't change anything in the arrow direction...

But Using the complex Source with <ScaleOffset> and <ScaleRatio> worked
fine for me.

Thanks again!

LP

On 03/05/2018 02:15 PM, Eichner, Andreas - SID wrote:
> Hi,
>
> since you're using GDAL VRT have you tried the "Scale" and "Offset" child 
> elements for a VRTRasterBand?
> I'd guess, using
>
> <VRTRasterBand band="1">
>   <Scale>-1.0</Scale>
>   <Offset>360.0</Offset>
>   ...
> </VRTRasterBand>
>
> might work for you.
>
>
> Regards,
> Andreas
>
>> -----Original Message-----
>> From: mapserver-users [mailto:[email protected]]
>> On Behalf Of Rousseau Lambert2, Louis-Philippe (EC)
>> Sent: Monday, March 05, 2018 2:46 PM
>> To: [email protected]
>> Subject: [mapserver-users] Wind direction files rotation using
>> CONNECTIONTYPE uvraster
>>
>> Hi all,
>>
>> What I'm trying to do:
>>
>> *    I want to display wind arrows using 2 files: wind direction and
>> wind speed. I am using the "CONNECTIONTYPE uvraster" feature to display
>> our arrows. Because we don't have U and V wind vectors in the North-
>> South direction for some models, we use the WIND and WDIR files which
>> are respectively wind speed and wind direction (in the North-South
>> direction, or Earth relative). So as input for my layer in MapServer I
>> have a VRT where band 1 is the wind direction (from 0 to 360 degres) and
>> band 2 is the wind speed. Instead of letting MapServer calculates the
>> resulting arrows speed and direction I'm using the raw value of u ([u])
>> as wind direction and the raw value of v ([v]) as my wind speed. So far
>> so good.
>>
>>
>> My problem is:
>>
>> *    The arrow rotation is done using the ANGLE keyword and [u] (wind
>> direction). But the ANGLE rotates the arrows in the counter clockwise
>> direction while the wind direction files increase in a clockwise
>> direction... Because we are using wind direction and wind speed files
>> (raw values of [u] and [v]) we can't use the [uv_minus_angle] and I know
>> that MapServer docs says that no processing can be done on the ANGLE
>> feature. I know that I would have to do some pre-processing (like 360-
>> [u]) and that would solve the problem. But I would have to do this for
>> hundreds of file per day and I'm trying to avoid as much as possible
>> pre-processing.
>>
>> Can you guys think of a solution that would not require pre-processing?
>> I tried playing with the arrow position and other little things but I
>> could not make it work correctly and I'm pretty much out of ideas...
>>
>>
>> Thanks
>>
>> LP
>>
>


-- 
Louis-Philippe Rousseau Lambert, B.Sc.
Géomaticien / Geomatician
Section des Données, Performances et Standards
Data, Performance and Standards Section
Service Météorologique du Canada
Meteorological Service of Canada
Environnement et Changement Climatique Canada
Environment and Climate Change Canada
[email protected]
(514) 421-5045

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