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Physical correct??
Posted: Thu Jul 19, 2012 12:43 am
by Rich_Art
Hi All,
See attached image/chart.
When I use this chart the lighting in the scene is waaaaay to bright.
In my best knowledge I thought Indigo is a Physical correct engine but when I use physical correct setting in a cam, it does not look really cool.
See my current cam settings with those settings it renders ok (see attached c4d file)
But when I use the settings as seen on the chart it is way to bright.
For example:
F-stop: 16
Exposure duration: 1/4s
EV: 10
ISO: 100
Anybody an idea?
Or do I see things wrong on the chart?
The scene is in cm....
Re: Physical correct??
Posted: Thu Jul 19, 2012 1:07 am
by Rich_Art
Attached another example.
It looks like the EV setting in Indigo is the opposite as seen on this chart..
When I have a bright sunny day and I set the EV to 16... you understand it will blow out the scene complete.
On the chart you can see that a night shot (moon) has to have an EV of -2 or -3 !!!!
Peace,
Rich_Art.
Re: Physical correct??
Posted: Thu Jul 19, 2012 1:20 am
by Zom-B
For EV the technical manual references it like that:
tonemapping :: camera :: ev_adjust
ev_adjust is exposure-value adjustment; increasing this value by 1 will effectively double the 'sensor output'.
It is a pure Tonemapping value, not interacting with fstop and shutter speed as in real world cameras:
http://en.wikipedia.org/wiki/Exposure_value
But anyway, I hope I didn't mixed up stuff here ^^
Re: Physical correct??
Posted: Thu Jul 19, 2012 1:38 am
by fused
Hi Rich_Art,
I think you might be misunderstanding the charts/EV adjust.
The settings you used(fstop 16, exposure 1/100) correspond to an EV of 15-16, which is, as you can see on the second chart you posted a "Typical scene in full or slightly hazy sunlight".
The EV in the camera tonemapping is for adjusting the EV (therefore the name, "EV adjust"). For recreating an EV from the charts you should leave it on 0.0.
You can also verify (via eyeballing) that Indigo's brightness is more or less correct if you try out the sunny 16 rule:
http://en.wikipedia.org/wiki/Sunny_16_rule
Re: Physical correct??
Posted: Thu Jul 19, 2012 2:24 am
by Rich_Art
Thanks guy's..
I'm using the sunny 16 rule..
I thought the EV in Indigo is the same EV as seen on those charts but apparently that is not the case.
Anyway thanks for the clarification..
Peace,
Rich_Art.
Re: Physical correct??
Posted: Thu Jul 19, 2012 5:22 am
by pixie
Rich_Art wrote:Thanks guy's..
I'm using the sunny 16 rule..
I thought the EV in Indigo is the same EV as seen on those charts but apparently that is not the case.
Anyway thanks for the clarification..
Peace,
Rich_Art.
I do use this rule without any problem, 16 is on the f-stop (aperture) 100 is on time (since I have 100 on iso) and ev is set to 0 so it doesn't it interfere. Work always as a charm.
Code: Select all
The basic rule is, "On a sunny day set aperture to f/16 and shutter speed to the [reciprocal of the] ISO film speed [or ISO setting] for a subject in direct sunlight."
The EV on indigo for C4D is the same as on the first table, you have the aperture in the row on top and have the time in the cells, which gives you the EV on the collumn on the left.
Re: Physical correct??
Posted: Thu Jul 19, 2012 8:02 pm
by StuDIO
Hi - the test scene you uploaded renders quite alright
this is what I saw straight from your file -
Re: Physical correct??
Posted: Thu Jul 19, 2012 8:03 pm
by StuDIO
ignore me - I havn't has my coffee yet...
(RTFM)
Re: Physical correct??
Posted: Thu Jul 19, 2012 9:03 pm
by Rich_Art
pixie wrote:
The EV on indigo for C4D is the same as on the first table, you have the aperture in the row on top and have the time in the cells, which gives you the EV on the collumn on the left.
Yes I see but have you test it??
If I look at the chart and pick the following F-stop and time,
F-stop: 16
shutter speed: 1/125
Then the EV should be set to 15, that is not correct of course because the scene will be way to bright..
As fused stated,
The EV in the camera tonemapping is for adjusting the EV (therefore the name, "EV adjust"). For recreating an EV from the charts you should leave it on 0.0.
So i'll leave it as it is and only make minor adjustments...
better play with Fstop, iso and shutter speed..
Peace,
Rich_Art.
Re: Physical correct??
Posted: Thu Jul 19, 2012 10:45 pm
by pixie
Well, now that I look more into it I've got to say that somehow your chart is wrong or at least meaningless, if you could post it in context, one might try understand where it came from.
Pick any manual camera you'll see it will have the same problems you're getting with indigo...
Re: Physical correct??
Posted: Thu Jul 19, 2012 11:08 pm
by Rich_Art
Yeah that is what I thought as well.
The chart is from wiki.
http://en.wikipedia.org/wiki/Exposure_value
Peace,
Rich_Art.