Sophie: blender-manual-2.49a-1ark i586

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>Blender Documentation Volume I - User Guide: Last modified April 29 2004 S68</TH
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>Motion Blur</H1
><P
>&#13;			Blender's animations are by default rendered as a sequence of
			<I
CLASS="emphasis"
>perfectly still</I
> images.
		</P
><P
>&#13;			This is unrealistic, since fast moving objects do appear
			to be 'moving', that is, blurred by their own motion, both in
			a movie frame and in a photograph from a 'real world camera'.
		</P
><P
>&#13;			To obtain such a Motion Blur effect, Blender can be made to
			render the current frame and some more frames, in between
			the real frames, and merge them all together to obtain
			an image where fast moving details are 'blurred'.
		</P
><DIV
CLASS="figure"
><A
NAME="BSG.REN.F.S68.701"
></A
><DIV
CLASS="mediaobject"
><P
><IMG
SRC="PartR/rendering/gfx/MBlur01.png"></P
></DIV
><P
><B
>Figure 18. Motion Blur buttons.</B
></P
></DIV
><P
>&#13;			To access this option select the <TT
CLASS="literal"
>MBLUR</TT
>
			button next to the <TT
CLASS="literal"
>OSA</TT
> button
			in the <TT
CLASS="literal"
>Render</TT
> Panel 
			(<A
HREF="x7845.html#BSG.REN.F.S68.701"
>Figure 18</A
>).
			This makes Blender render as many 'intermediate' 
			frames as the oversampling number is
			set to (5, 8, 11 or 16) and accumulate them, one over 
			the other, on a single frame.
			The number-button <TT
CLASS="literal"
>Bf:</TT
> or Blur Factor
			defines the length of the shutter time
			as will be shown in the example below.
			Setting the <TT
CLASS="literal"
>OSA</TT
> Button is unnecessary since the
			Motion Blur process adds some antialiasing anyway, but to
			have a really smooth image <TT
CLASS="literal"
>OSA</TT
> can be activated too.
			This makes  each accumulated image have anti-aliasing. 
		</P
><P
>&#13;			To better grasp the concept let's assume that we have a cube,
			uniformly moving 1 Blender unit to the right at each frame.
			This is indeed fast, especially since the cube itself
			has a side of only 2 Blender units.
		</P
><P
>&#13;			<A
HREF="x7845.html#BSG.REN.F.S68.702"
>Figure 19</A
> shows a render of frame
			1 without Motion Blur, <A
HREF="x7845.html#BSG.REN.F.S68.703"
>Figure 20</A
>
			shows a render of frame 2. The scale beneath the cube helps
			in appreciating the movement of 1 Blender unit.
		</P
><DIV
CLASS="figure"
><A
NAME="BSG.REN.F.S68.702"
></A
><DIV
CLASS="mediaobject"
><P
><IMG
SRC="PartR/rendering/gfx/MBlur02.png"></P
></DIV
><P
><B
>Figure 19. Frame 1 of moving cube without motion blur.</B
></P
></DIV
><DIV
CLASS="figure"
><A
NAME="BSG.REN.F.S68.703"
></A
><DIV
CLASS="mediaobject"
><P
><IMG
SRC="PartR/rendering/gfx/MBlur03.png"></P
></DIV
><P
><B
>Figure 20. Frame 2 of moving cube without motion blur.</B
></P
></DIV
><P
>&#13;			<A
HREF="x7845.html#BSG.REN.F.S68.704"
>Figure 21</A
> on the other hand
			shows the rendering of frame 1 when Motion Blur is set
			and 8 'intermediate' frames are computed. Bf is set to 0.5;
			this means that the 8 'intermediate' frames are computed on
			a 0.5 frame period starting from frame 1. This is very evident
			since the whole 'blurriness' of the cube occurs on half
			a unit before and half a unit after the main cube body.
		</P
><DIV
CLASS="figure"
><A
NAME="BSG.REN.F.S68.704"
></A
><DIV
CLASS="mediaobject"
><P
><IMG
SRC="PartR/rendering/gfx/MBlur04.png"></P
></DIV
><P
><B
>Figure 21. Frame 1 of moving cube with motion blur, 8 samples, Bf=0.5.</B
></P
></DIV
><P
>&#13;			<A
HREF="x7845.html#BSG.REN.F.S68.705"
>Figure 22</A
> and 
			<A
HREF="x7845.html#BSG.REN.F.S68.706"
>Figure 23</A
> show the effect of increasing Bf
			values. A value greater than 1 implies a very 'slow' camera shutter.
		</P
><DIV
CLASS="figure"
><A
NAME="BSG.REN.F.S68.705"
></A
><DIV
CLASS="mediaobject"
><P
><IMG
SRC="PartR/rendering/gfx/MBlur05.png"></P
></DIV
><P
><B
>Figure 22. Frame 1 of moving cube with motion blur, 8 samples, Bf=1.0.</B
></P
></DIV
><DIV
CLASS="figure"
><A
NAME="BSG.REN.F.S68.706"
></A
><DIV
CLASS="mediaobject"
><P
><IMG
SRC="PartR/rendering/gfx/MBlur06.png"></P
></DIV
><P
><B
>Figure 23. Frame 1 of moving cube with motion blur, 8 samples, Bf=3.0.</B
></P
></DIV
><P
>&#13;			Better results than those shown can be obtained
			by setting 11 or 16 samples rather than 8, but, of course,
			since as many <I
CLASS="emphasis"
>separate</I
> renders as samples 
			are needed a Motion Blur render
			takes that many times more than a non-motion blur one.
		</P
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>Better Anti-Aliasing</B
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>&#13;				If Motion Blur is active, even if nothing is moving
				on the scene, Blender actually 'jitters' the camera a little
				between an 'intermediate' frame and the next. This implies
				that, even if OSA is off, the resulting images have nice
				Anti-Aliasing. An MBLUR obtained Anti-Aliasing is comparable
				to an OSA Anti-Aliasing of the same level, but generally
				slower.
			</P
><P
>&#13;				This is interesting since, for very complex scenes
				where a level 16 OSA does not give satisfactory results,
				better results can be obtained using <I
CLASS="emphasis"
>both
				</I
> OSA and MBlur. This way you have
				as many samples per frame as you have 'intermediate' 
				frames, effectively giving oversampling
				at levels 25,64,121,256 if 5,8,11,16 samples
				are chosen, respectively.
			</P
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