[Liblas-devel] Re: Writing Scan Angle Rank values

[Mateusz Loskot]

Howard Butler wrote:
> 
> On May 1, 2008, at 1:11 PM, Howard Butler wrote:
> 
>> Mateusz,
>>
>> The specification says the following for Scan Angle:
>>
>> Scan Angle Rank (-90 to +90) – Left side unsigned char 1 byte *
>>
>> We are doing the following:
>> int8_t GetScanAngleRank() const;
>> void SetScanAngleRank(int8_t const& rank);
>>
>> int8_t is defined as:
>>
>> typedef signed char     int8_t;
>>
>>
>> If I write the following:
>> p = point.Point()
>> p.scan_angle = -90
>>
>> The Scan Angle returned is:
>>
>> Scan Angle Rank:    166
>>
>>
>> Do you have any idea why the Scan Angle Ranks cannot be roundtripped?  
>> I would expect the Scan Angle Rank to be -90 in the file as I have set 
>> it.  The specification is unclear to me.  If we are supposed to store 
>> Scan Angle Rank as an unsigned char, how are  we to store negative 
>> values?  Are we supposed to determine +/- from the Scan Direction and 
>> then store 0-90 in the Scan Angle Rank?
> 
> 
> My dumb.  I was using uint8_t in the C API and clipping things off.  
> Sorry.  Fixed in r626 http://liblas.org/changeset/626/

Ah, OK.
Honestly, it was a big mystery to me why the value is wrong.

Greetings
-- 
Mateusz Loskot
http://mateusz.loskot.net