[Sidefx-houdini-list] Compositing -> Deep Raster -> Targa

Jeff Wagner jeff at sidefx.com
Mon Mar 6 12:51:25 EST 2006


Fyi it isn't anti-aliased for a very good reason: it is very precise so 
you don't get rounding errors. There is an option to have it quantize if 
you want.  Generally Pz should NOT be quantized and left at 32 full 
float or run in to compositing issues later on.


-jeff

Andrew D Lyons wrote:

>Tiff should work - but aside from the file format - last time I
>looked, Pz out of Houdini wasn't anti-aliased. You end up with square
>(micro-polygon size) edges. For smoother zdepth you can create a vex
>shader and render an extra pass:
>
>1./ Global variables vop
>2./ length vop
>3./ shift vop
>
>* Wire "I" from Globals into length.
>* Wire length into val in the shift vop.
>* Work out the most distant object in your render, and set up new
>range in your shift vop. (Render all scene layers with this range.)
>
>>From here you can do two things to output:
>
>1./export a value using a parameter vop and set up a deep raster
>output for the exported depth value.
>
>2./ add a float to vec vop and wire shift into all three (or just one)
>value of the float2vec. From here you can wire straight into Cf and
>render a seperate color pass.
>
>Cheers
>
>
>
>On 06/03/06, Marshall Petersen <hfsidefx at gmail.com> wrote:
>  
>
>>Well I've been playing around with the Tiff's and I'm still having
>>problems. First I changed the renders to Tiffs, and the data types to
>>Float. However this was giving me blank results on the zDepth, so I
>>then changed the variable from Pz to just P, thinking that I could
>>then extract that data from the Blue channel of the tiff, but it still
>>seems to be clipping the data. Any other ideas??  Any help would be
>>great thanks.
>>
>>MP
>>
>>On 3/6/06, Mark Alexander <malexander at sidefx.com> wrote:
>>    
>>
>>>Targa only supports 8bit images, so what's happening is your depth,
>>>which is likely greater than 1, is being clipped to the 0-1 range. So
>>>you get 0 for pixels where no objects are, and your clipped depth (1)
>>>for your objects - which looks like an alpha matte.
>>>
>>>Try TIFF instead - it supports 32 bit floating point images, and should
>>>store your Z maps with ease.
>>>
>>>M.
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>>>      
>>>
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>>    
>>
>
>
>--
>=======================================
>Andrew D Lyons | Digital Artist | http://www.tstex.com
>=======================================
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-- 
Jeff Wagner, jeff at sidefx.com, Senior Technology Consultant
Side Effects Software, www.sidefx.com, Toronto, Ontario, M5V 3E7
tel: (416) 504-9876, fax: (416) 504-6648




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