[ptx] HFOV, focal distance...

[Terje Mathisen]

ptx-bounces at email-lists.org wrote:

> manouchk schrieb:
> 
>> Le Lundi 30 Mai 2005 08:55, Emmanuel a écrit :
>>
>>> Hi,
>>>
>>> I'd like to know if providing a good value of the HFOV is sufficient
>>> to do
>>> a good stitching in hugin or if it is needed to adjust well the focal
>>> length and cropping ?
>>
>>
>>
>> As noone seems to know the answer of my previous question, I ask my
>> question in another way, what is the cropping factor?
> 
> 
> The difference of the 35 mm film diagonal (~43.5 mm) divided by the real
> sensor diagonal.
> 
> But this is only needed if you want to input the focal length and not
> the hfov directly.
> Leave the crop factor at 1, if you use the 35 mm film equivalent focal
> length (usually in the range of 35-90, or so).
> 
>> I have other questions is it possible to optimize HFOV in a 360° pano
>> in hugin? If yes how?
> 
> 
> I guess you mean the HFOV of the input images.
> Sure, by selecting an optimisation mode where the HFOV is optimized, for
> example "y,p,r and v", or with the custom settings.
> 
>> The HFOV of my camera (of poor guy) is a olympus C40 zoom if anyone
>> can help me for HFOV, cropping etc..?
> 
> 
> According to some info on the internet, the C40 has an equivalent focal
> length of 35-98 mm.
> 
> just enter 1 as the crop factor and 35 for the focal length, if your
> images where taken without zoom, and 98 mm if they where taken with zoom.

My previous camera was a D40Z (same camera, US model).

After literally days of calibration, I came up with the following
parameters:

Max wide angle (7,5 mm, Portrait mode):
  a: 0,006312, b: -0,028406, c: 0,011234, HFOV: 39,654

Max zoom (19,8 mm, Portrait):
  a: -0,000391, b: -0,002956, c: 0,003308, HFOV: 15,554


The tele parameters are particularly good, mosaics taken using those
usually show very close to zero residual control point errors after
optimization.

Terje
-- 
- <Terje.Mathisen at hda.hydro.com>
"almost all programming can be viewed as an exercise in caching"