Defocus is inacurate #24534

New Issue

Moolah Nasreddin · 2010-11-04T14:49:11+01:00

Moolah Nasreddin commented

2010-11-04 14:49:11 +01:00

%%%Blender 2.5 r32760

I tried to understand - what's wrong with Defocus. When I'm shooting in real life - (so called) super macro gives sharper "beginning" of the focused area if I set f=8.0 or closer and a nice smooth gradient to a blurred area. But when I tried numbers for fStop closer almost to 128 (127.8 or even 127.999) it gives unnatural results. It looks like grading between 127 and 128 is none.
Increasing or decreasing MaxBlur gives not better results - everything outside focus area is too blurred or too sharp.
I don't know what is it? Some approximation in formulae or something other?
Believe me - I don't care about trifles but this is a bit annoying then we can't get a better result for Defocus inside Blender yet.%%%

%%%Blender 2.5 r32760 I tried to understand - what's wrong with Defocus. When I'm shooting in real life - (so called) super macro gives sharper "beginning" of the focused area if I set f=8.0 or closer and a nice smooth gradient to a blurred area. But when I tried numbers for fStop closer almost to 128 (127.8 or even 127.999) it gives unnatural results. It looks like grading between 127 and 128 is none. Increasing or decreasing MaxBlur gives not better results - everything outside focus area is too blurred or too sharp. I don't know what is it? Some approximation in formulae or something other? Believe me - I don't care about trifles but this is a bit annoying then we can't get a better result for Defocus inside Blender yet.%%%

Moolah Nasreddin commented

2010-11-04 14:49:11 +01:00

Changed status to: 'Open'

A Saurus1 commented

2010-11-05 00:42:20 +01:00

%%%On a hunch, have you tried increasing the Threshold value?

Also, if you want more control, you could always map the output of the Z buffer to the size input for a blur node and control the blur that way...

I'm not sure this is a bug.%%%

%%%On a hunch, have you tried increasing the Threshold value? Also, if you want more control, you could always map the output of the Z buffer to the size input for a blur node and control the blur that way... I'm not sure this is a bug.%%%

Moolah Nasreddin commented

2010-11-05 01:25:26 +01:00

%%%Yes, I tried all, I think :) The threshold fixes blur bleeding - not gives a smooth gradient, quite the reverse - it gives very sharp edge between focused and blurred area. It's not fixing the issue that I described.
Of course - it's not a major thing but still may be very useful if will be working as expected.%%%

%%%Yes, I tried all, I think :) The threshold fixes blur bleeding - not gives a smooth gradient, quite the reverse - it gives very sharp edge between focused and blurred area. It's not fixing the issue that I described. Of course - it's not a major thing but still may be very useful if will be working as expected.%%%

Campbell Barton commented

2010-11-05 04:03:19 +01:00

%%%Confirmed this gives results which seem incorrect.
assigning to Ton.%%%

%%%Confirmed this gives results which seem incorrect. assigning to Ton.%%%

Ton Roosendaal commented

2010-11-09 18:58:50 +01:00

%%%Well; the defocus code was submitted by Matt, who got it from Eeshlo "as is", without maintenance. It works this way since the beginning, and afaik nobody managed to understand the code well (i gave up!).
I've asked Durian artists, and they confirmed this issue. They just work around it...

Note that this compositor effect is a post process, and not meant to give "real" focus effects. I think the issue is a built-in limitation of the code, which can only be solved with careful recode. Reason to mark the issue a "todo", and will post it on our wiki here http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Tools#Compositing

Thanks!%%%

%%%Well; the defocus code was submitted by Matt, who got it from Eeshlo "as is", without maintenance. It works this way since the beginning, and afaik nobody managed to understand the code well (i gave up!). I've asked Durian artists, and they confirmed this issue. They just work around it... Note that this compositor effect is a post process, and not meant to give "real" focus effects. I think the issue is a built-in limitation of the code, which can only be solved with careful recode. Reason to mark the issue a "todo", and will post it on our wiki here http://wiki.blender.org/index.php/Dev:2.5/Source/Development/Todo/Tools#Compositing Thanks!%%%

Ton Roosendaal commented

2010-11-09 18:58:50 +01:00

Changed status from 'Open' to: 'Archived'

Ton Roosendaal closed this issue

2010-11-09 18:58:50 +01:00

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Defocus is inacurate #24534