[Bf-vfx] Focal length constraints usability

Wed Aug 28 14:09:46 CEST 2013

Great feedback, thanks! In some ways I like the idea of having a separate
"estimated focal length", but in addition to the UI inflation problem, it
also might be confusing as to whether the estimated or real focal length
property is being used. Would the estimated focal length be used when
refinement is enabled? Or only when the constraint is enabled?

I definitely agree that the default values shouldn't be 0.0 and 0.0 - that
was a mistake! If you hover over the fields, it tells you the units they're
in, which match the units chosen for the focal length in the properties
shelf. Is this also confusing? We preferred this to having separate unit
selections for each shelf.

Sergey - is your suggestion with the clamping that if, for example, min and
max are 18mm and 24mm but the focal length is given as 26mm, it would first
move it into the range to 24mm before starting the solve?

On 28 August 2013 12:37, Sebastian König <koenig.sebastian at gmx.net> wrote:

> I think I would prefer absolute.
> Because either I set a fixed focal length and solve for that, or I use
> focal length and let blender do refinement (both options are what we had
> until now).
> Or, and that would be the new one, I know the focal length must be
> something between 18 and 23 or so. In that case i would simply set these
> values and then let blender figure out the refined focal length.
> So actually Sergey is right and we can make it totally independent from
> focal length setting.
>
> And how about trying to save some space in the UI?
> Min/Max values could always with update with the focal length setting and
> display the same value. And if I want to use different min/max constraints,
> i simply change the values and they will be used. That way we could avoid a
> checkbox.
>
> Seb
>
>
>
> --
> Sebastian König
> Schenkendorfstrasse 45
> 04275 Leipzig
> Germany
> +49 176 20319318
> www.3dzentrale.com
> koenig.sebastian at gmx.net
>
> On 28. August 2013 at 13:25:33, Sergey Sharybin (sergey.vfx at gmail.com)
> wrote:
>
> Thanks for the feedback, Sebastian!
>
> We might do it so min/max are totally independent from focal length, an
> could be set to any value. Then, when we start solution, focal length gets
> clamped to hat range internally (no user action is needed for this).
>
> Also, you didn't tell your opinion about using relative option. Which
> mean, instead of having absolute min/max you'll define mm/px delta from
> focal length set in camera panel, and focal length would be refined in
> range of [ initial_focal_length - delta; initial_focal_length + delta ].
> Does it seem more clear for you?
>
>
> On Wed, Aug 28, 2013 at 4:23 PM, Sebastian König <koenig.sebastian at gmx.net
> > wrote:
>
>> Hey!
>>
>> Great to hear it is getting closer to be trunkified!
>> I just tried a test build from 3 days ago from graphicall and noticed a
>> few things, related to workflow.
>> Having never really tested your branch or really knew what it is about I
>> think it was a good test what a user would think if he first sees the
>> constraint options. :)
>>
>> So:
>> - Having the two values set to 0.000 first was a bit strange, because I
>> didn't know what the values represent. If the values will stay in mm, then
>> maybe it would be nice to have them at the default focal length at first.
>> 24mm for example
>>
>> - After I figured out what the min/max values are, I wanted to test how
>> they work. I have set the min value to 18, and then tried 23 for max value.
>> But because i didn't change the default setting of 24, I couldn't change it
>> to anything smaller than that, which makes sense of course, but felt a bit
>> weird. So I guess i would rather like the expanding way of dealing with
>> that.
>> Because let's suppose I know the focal length is something in between 18
>> and 22. If i see the constraint setting I would think that that's the place
>> where I can control the refinement. But if I don't touch the focal length
>> setting in properties panel, I cannot set the max value to 22. So I think
>> it would be nice if focal length in that case would just switch to 22, the
>> max setting.
>> Or, if i know it's something in between 30 and 35, the focal length would
>> switch to the 30, the min setting.
>>
>> - Right now I have to look in the toolshelf and the properties, to the
>> left and right of the screen for dealing with this. I think it would be
>> nice to have it all in one panel. So the camera data in properties could
>> still have all the settings for focal length etc, but since trying to guess
>> the right focal length and setting the constraints for it now becomes more
>> of a tool itself, there could be a setting for estimated focal length in
>> the solve panel. Below that you have the 2 min/max settings for upper/lower
>> threshold. If you set the estimated focal length bigger or smaller then the
>> min/max settings below, it could expand accordingly. Because the 3 settings
>> are then very close together it becomes more obvious to the user how they
>> relate and what happens.
>>
>> - the question is then still what happens if the user changes the focal
>> length value in the properties. But in that case I think it could just
>> override the estimated focal length.
>>
>> I agree with Sergey, it does get a bit crowded, and what I just suggested
>> would probably only make it worse. But rearranging the buttons is maybe not
>> that big of a problem.
>>
>> I hope that makes sense. Can also discuss with Sergey on irc, maybe I can
>> make these walls of text more clear there. ;)
>>
>> Cheers!!
>>
>> Seb
>>
>>
>>
>>
>> On 27. August 2013 at 20:58:18, Joseph Mansfield (sftrabbit at gmail.com)
>> wrote:
>>
>> Hey everybody,
>>
>> I'm getting my focal length constraints work ready to commit to trunk but
>> I have a couple of things to ask about how the interface should work before
>> doing so.
>>
>>    1. The current minimum and maximum fields take absolute values (in
>>    either mm or px). Would it be more useful to provide an interval (say ±5%
>>    or ±2mm)? If so, the next question is irrelevant. Perhaps both options
>>    should be available, if it would be useful.
>>    2. I currently have it so that, only if the constraint is enabled,
>>    the focal length intrinsic in the properties shelf cannot be adjusted
>>    outside of this constraint. Sergey has pointed out that the constraint is a
>>    tool property and shouldn't restrict any other property. So here are the
>>    other options:
>>
>>
>>    1. Expand the constraint whenever the focal length is changed to
>>       outside the range.
>>       2. Allow the focal length to go outside the constraint, but give
>>       an error if a solve with refinement is attempted.
>>       3. Don't have any restriction at all (if you attempt a refinement
>>       with the focal length outside the constraint, the given focal length
>>       doesn't really mean anything.
>>
>> So, please let me know what you think. Thanks!
>>
>> Joseph Mansfield
>>
>>
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>>
>
>
> --
> With best regards, Sergey Sharybin
>
>
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