Nuke Workflow for visual effects and grading

[Louis Eguchi]

Hi

I am making a short visual effects film using the red one as part of an assignment at university. So we have a lot of visual effects to do within Nuke X stuff like merging the raw footage with CGI renders, doing match moving etc. I am now starting to think about the grade (haven't touched the footage yet) i originally did the edit in Premiere pro and exported used 720p tiff sequences for use in nuke for faster workflow.

Now i have got that edit in Red Cine X Pro and want to be able to out put raw redtrim files but at a smaller resolution say 720p. it doesn't seem this is possible?
The reason i want to be able to do this is because Nuke Does support changing all the raw data just like in RCXP and would be useful because i could change the grade in context of our CG elements. however 4K is too big for my computer to handle compositing 4k and its painful to work with. and as a student i do not have access to a red rocket!

additionally Ive heard that red cine x offers really just preliminary grade options, and basically having forked out a lot of money to be able to shoot RED one footage i am looking to get the best results using as much raw data as possible. is there a better workflow say for doing a preliminary grade in red cine x and then say moving to something like davinci for a final grade? if so what format should i use? open EXR, PDX?

any suggestions or advice would be fantastic!

[Adam Clark]

i don't believe you can change resolution in redcine-x for r3d trims, nor would you want to even if your machine can't comp 4k.

here's why:
we're doing vfx for a show right now that was shot 4k, but will be mastered at 2k. we're pulling the 4k r3d trims from the source footage and bringing into eyeon fusion, which like nuke, is node based and very similar. for most of the shots, we use a 2k resize and crop node straight off the file load node effectively making it 2k computationally for the rest of the comp pipeline. but when we need the resolution (tricky keys, exporting a sequence to a 3d tracking app, reframing, etc) we have it. the same would be true for lower master resolutions.

good luck.

[Louis Eguchi]

Thanks for getting back to me!
Your right. i can do this in nuke too, drop a reformat node straight after reading the file and after an initial slow cache i can work with the a lower res version down the pipeline. but i did wonder oh well it would be great to use the 4k for keys but surely not because the pixals on the edges change a lot. a alpha matte produced from a key on a 4k would not turn out well when used on 2k? baring in mind im keying hair and close up shallow depth of field.
Maybe im just complicating this and should pick a resolution and go for it.

additionally my reasoning for wanting 720p r3d files is because when i used 720p tiffs made from the 4k r3d files playback after changing something small down the node network runs pretty much 5 times faster than the tests im doing now - using 4k r3d then reformatting to 720p then making a change it takes about 0.8 frames a secound to cache to be able to play back at max 24fps. maybe i will just have to accept this.

[Adam Clark]

most of the time i'll be able to get away with keying after the resize, but depending on source (blond hair on greenscreen, grime on windshields, etc), i'll key off the 4k and then resize after to match the rest of the comp. the difference is that for things like hair, the resize/resample will anti-alias and introduce color contamination into delicate areas where it otherwise should not be, especially dealing with fine hair where every clean pixel counts. resizing after the key is better clearly in this case as you are resizing a clean alpha vs pulling a key from a resized/resampled source.

as far as using 720p for speed of processing. create a 720 proxy sequence and pipe in for proxy mode for fast working then turn off proxy to see full rez.