[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[THREDDS #XRG-961762]: Questions about the OPeNDAP DataSet Access Form



Jasmine,

Yes, that is what you should do with the scale and offset. The data returned by 
opendap for any of the radar data variables (like reflectivity) should be 
single byte
*unsigned* values in the range 0 to 255. Applying the scale and offset will 
convert them to values in the range -33 to 94.5 by the formula:

scaled_value = byte_value * 0.5 + -33.

If the values look weird, it's possible the opendap client you're using isn't 
handling the unsigned values properly and is instead giving you byte values in 
the range
-128 to 127; in this case the negative values won't scale properly using the 
above formula.

Ryan

> Good afternoon,
> Thank you for your previous answer.
> 
> I do have another question please.
> Indeed, in the reflectivity variable, it is said
> - scale factor = 0.5
> - add offset = -33.0
> Are we supposed to divide each reflectivity value per 2 and add an offset
> of -33dbZ per value ?
> 
> Because, when we take a look at the reflectivity value with a scale of the
> reflectivity meaning it does match so well.

Ticket Details
===================
Ticket ID: XRG-961762
Department: Support THREDDS
Priority: Normal
Status: Closed


NOTE: All email exchanges with Unidata User Support are recorded in the Unidata inquiry tracking system and then made publicly available through the web. If you do not want to have your interactions made available in this way, you must let us know in each email you send to us.