Author Topic: Render size  (Read 6009 times)

2016-03-18, 09:01:49

K u r a i

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I always doubt what render size to render at.

I render at 3840 x 2160p. I have read that animators render at double the size and then reduce by 50% for the final image (1920x1080).
This softens the hard edges and helps in Photoshop if you want to doctor things.

I am not talking about print. I am concerned about what size to render at for web.

At the end of the day, rendering at 4K takes alot of time and the file sizes are big.

Can someone educate me on this subject?




2016-03-18, 12:28:04
Reply #1

SairesArt

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I always doubt what render size to render at.

I render at 3840 x 2160p. I have read that animators render at double the size and then reduce by 50% for the final image (1920x1080).
This softens the hard edges and helps in Photoshop if you want to doctor things.

I am not talking about print. I am concerned about what size to render at for web.

At the end of the day, rendering at 4K takes alot of time and the file sizes are big.

Can someone educate me on this subject?
What you describe is the use of supersampling.
This may be true for media where you cannot control the varibles that determine softness, edges and general quality. For instance in games, that cannot do multisampled antialiasing, because deffered render structures dont allow it, Cameras where sharpness can be pushed that way.

But for pathtracing this does not make any sense.

This softens the hard edges
This is where filters come into play, which work at subpixel level. Jurai preaches 3px filters especially for higher resolution images. Samples are interpreted as having a 3px influence and thus dont generate the hard "Computery" look when dealing with photorealistic renders.

Everything else can be tuned, without supersampling. It really is not the right choise, unless you need the high res for print or something else.

Stay with the resolution you try to finilize for, if you got questions how to achive a certain look feel free to ask.

2016-03-18, 14:15:59
Reply #2

K u r a i

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So, you are saying I should stick with my present render size of 4K?

But, you mention 3px filter that Juraj uses. How do I do this?
Where is this located and recommended setting? Are you talking about the TENT FILTER?

I always find the image looks best when you first start rendering and it has abit of noise in it.
Slowly though, as the image gets clearer over time, the image becomes too sharp and looks computer generated.
I really dislike this.... and would prefer a softer edge.

2016-03-18, 18:12:14
Reply #3

Juraj Talcik

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But for pathtracing this does not make any sense.


This is partially true imho :- )

It's true for anti-aliasing yes (with exception of hdr 'jaggies', which look smoother if glow and tonemapping is applied at higher-res and then down-sampled, or, Corona's "internal resolution".

But it's less so for detail. At higher resolution, shadow and texture detail (and effects, like bump/normal) converges to higher detail, shadows are bit more precise and textures are better filtered. When downsampling, this detail is preserved compared to rendering at native res.
Also, post-production is much less destructive at higher resolution, you don't have to be pixel-perfect with masking and worry so much about introducing additional noise and loss of detail.

Displays are getting bigger, almost every laptop on market is 3200 to 3840px. Lot of web imagery will start to be at this resolution soon (it's not size problem, because even currently, it's better to upload high-res but very compressed, then small res but good compression, same visual effect).

If you can, go high-res, it always looks better. Stuff I do gets always printed so for me it's not even choice.
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2016-03-18, 19:32:39
Reply #4

K u r a i

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Yes, well, that's all very fine and dandy.... and I admire the patting yourselves on the back routine ....but, getting back to my question...

What's this 3px theory.... and can it help my renders?

2016-03-18, 20:44:57
Reply #5

SairesArt

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So, you are saying I should stick with my present render size of 4K?
No, my point is, if you render for 1080p, render 1920x1080
To get rid of computer sharpness use higher than 1,5px tent image filter, for instance 3px.

Yes, higher res gives you finer control for masking, painting etc., but rendering 4k too get less computer look is wrong.

Edit: yes, 3px will make it less sharp
Also this is no back patting, this is important context to why he makes his point ;]

2016-03-18, 21:31:45
Reply #6

K u r a i

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Many thanks for the reply.

I often get confused at some of the terminology used in rendering... which in turn makes me upset, cos when you
want to get good at something... you really get eager to know more. There is always something more to learn.... and the rabbit hole gets deeper.

I am really happy about finding out the Tent filter info... increase from 1.5 to 3px will yield softer results. I will try it out. Great.
I did a Z depth pass (for the first time) and hope I can soften things with this in Photoshop.

I will stick with 4k even though it takes forever. If I use 1920 x 1080p I will always have a seed of doubt in my mind.




2016-03-18, 22:06:07
Reply #7

Juraj Talcik

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increase from 1.5 to 3px

This also has a context though.

I use higher filters (btw the new default filter size in 1.4 Corona will be 2.0 ) with higher resolution.
If you use 3px for 1920px, it will only be super blurry. It's ok for artistic renders, but not for crisp product shots and archviz.

There is no set value. It's personal preference. Some people prefer, or occasion calls for....perfect sharpness and clarity. On other, softness blends the scene for eye, and looks more photorealistic.
It's not better or worse.


Yes, well, that's all very fine and dandy.... and I admire the patting yourselves on the back routine ....but, getting back to my question...

What's this 3px theory.... and can it help my renders?

Also,....Kurai, I would suggest to curb these "smart" remarks or literally nobody will reply to you. There is fine line between being sharp and humorous...and being obnoxiously rude.
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2016-03-18, 22:55:39
Reply #8

K u r a i

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I am neither obnoxious or rude. And I feel sad that you should think that :(
I should have put a smiley face at the end of the comment to disarm it :)

But, I am impatient and have a dry humour. ...which could be easily misconstrued by someone straight laced ;-]
Thanks for your reply though. To the point and no tech talk. Great :))))