[Sidefx-houdini-list] Mantra crops

Simon Barrick simon at primalpictures.com
Sun Oct 29 07:11:55 EST 2006


Interesting idea, I'll have to have a play. Two questions immediately
spring to mind though.

1. Can you do this on a binary ifd file? If not then this is a no go as
non-binaries are too big.
2. This would still require making multiple copies of the ifd, it would
be nice to avoid this as that immediately brings its own management and
network issues.

We current do the m x n rop nodes method. And it works, its just a major
pain in the butt for anything other than single images.

Expect an rfe from me..... :)
Cheers!
Si

-----Original Message-----
From: sidefx-houdini-list-bounces at sidefx.com
[mailto:sidefx-houdini-list-bounces at sidefx.com] On Behalf Of Jeff Wagner
Sent: 28 October 2006 16:44
To: sidefx-houdini-list at sidefx.com
Subject: Re: [Sidefx-houdini-list] Mantra crops


What about a post-process directly on the single ifd using a simple 
shell script that modifies the generated ifd to do the same thing?

Just need to insert a ray_crop <x_min> <x_max> <y_min> <y_max> line 
after the ray_projection line (that's where it usually shows up if you 
have non-default crop settings).
Next generate a temp ifd and pass to mantra for as many times you crop 
up the image with appropriate ray_crop values as needed with two nested 
while loops.
I have done this in the past and it works just fine. You have two ifd's 
on disk at once and not all the necessary ones. Great if you have ifd's 
that are very large.

Post render script?
Could also use ROP script nodes after the main mantra node to simply 
execute scripts to do this visually. Would need m x n number of nodes...

I do agree that this would be nice as a built-in feature. Raise the crop

options to the mantra command options? Mark would know the best way.


-jeff

Peter Robbinson wrote:
> I would suppose then that you guys are building multi-camera hda's as
> a hack at the moment, while waiting for
> someone to build this properly into the renderer.
>
> PeterR
>
> Simon Barrick wrote:
>
>> Yeah that's basically the setup I have, but it's a pain when you have

>> 1000 of frames going through because each ifd is the same size and 
>> the content must be identical except for the cropping details. Its 
>> not too bad if everything is set to render from file but when it 
>> isn't just generating all the ifds takes a lot of time. Then there's 
>> the admin time to get all the bits comped together and find the bad 
>> bits, blah, blah... I have multiple scripts to handle all this but it

>> just struck me that mantra could just have a mode that did all this 
>> internally. Maybe its worth putting in an rfe. Si
>>
>> -----Original Message-----
>> From: sidefx-houdini-list-bounces at sidefx.com
>> [mailto:sidefx-houdini-list-bounces at sidefx.com] On Behalf Of Peter 
>> Bowmar
>> Sent: 26 October 2006 22:35
>> To: sidefx-houdini-list at sidefx.com
>> Subject: Re: [Sidefx-houdini-list] Mantra crops
>>
>>
>> R+H has a nice script that does this for you, and re-assembles it
>> afterwards too. For 20+ hour volumetric renders it saved the day many

>> times! I completely agree, there should be an option to output 
>> "slices" of an image, essentially one IFD per slice.
>>
>> Perhaps a HDA ROP could do this without any custom code, but someone 
>> would have to sit down and do it :)
>>
>> Cheers,
>>
>> Peter B
>>
>> On 26/10/06, Simon Barrick <simon at primalpictures.com> wrote:
>>  
>>
>>> Thought for the day....
>>>
>>> Whenever we are rendering really big print res frames with lots of
>>> geometry in we crop each frame up into 6-8 pieces and render each 
>>> bit seperately. This is unbelievably quicker than trying to do the 
>>> whole thing at once plus much less likely to fail. I've been doing 
>>> this for ages and now I've started thinking why the heck can't 
>>> mantra do this process internally? You'd think that it was doing 
>>> that with buckets anyway but yet cropping the frame always makes it 
>>> quicker and more stable. Has anyone else noticed this? If I'm not 
>>> imagining it surely this would be a nice feature for mantra....
>>>
>>> Ta
>>> Si
>>>
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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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