PanoTools NG:
Re: best practise for straight line control points?
Jim Watters 2008-Nov-25 17:03:50
paul womack wrote:
> Jim Watters wrote:
>
>> paul womack wrote:
>>
>>> I want the pano to be exactly square, so I need to set horizontal and vertical control points - of course, being a map, there are grid lines, ideally suited to placing such points.
>>>
>>> But what's best?
>>>
>>>
>> Horizontal and vertical control points are evaluated in single pairs.
>> Their order does not matter. I would place them as far apart as possible.
>>
>
> You mean (in my example) a 1-5 pair would be good?
>
Yes
> At one stage in my pano I had a square(ish) pano
> with (what I can only describe) as severe barrel
> distortion.
>
> I assume I'd need at least horiz line controls
> on 1-3 and 3-5 to control that, in addition to a 1-5
>
If the lens and camera has not already been calibrated for fov and abcde
values then yes it will be neccessary to add the additional control points.
>> For straight lines the first pair of points are compared to the other
>> pairs of points. It is best to place the first pair of points as far
>> apart as possible. Then add additional pair of points for that line.
>>
>> Straight line points are mostly a substitute when there is not enough
>> detail to add normal points.
>>
>
> Sorry to confuse - I'm not using "ordinary" straight lines at all.
>
If you do need to calibrate the lens then adding the straight points
will help this.
>> To keep the result square it probably is only necessary to add 2 of both
>> hor and vert lines. Three of each will not hurt. And only add the
>> straight lines if there is not enough detail to add other points.
>>
>
> BugBear
>
> ------------------------------------
>
>
--
Jim Watters
jwatters @ photocreations . ca
http://photocreations.ca
------------------------------------
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