Chaos Corona Forum
General Category => Gallery => Work in Progress/Tests => Topic started by: Majeranek on 2016-06-29, 09:59:21
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Hi guys,
I wanted to show you one of my last renderings I'm working on.
I like the mood of it. However, for some time all of my renderings have that "blurry feel" and I can't produce sharp images. Even when I'm using CoronaSun with sharp lighting I get that blur.
Maybe you can tell me what could be improved?
Cheers.
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I know that some people use a highpass in photoshop on overlay to try and sharpen up images. I'm not a fan of sharpening images that often but maybe it could help you?
attached a quick copy of your image with the highpass over the top.
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I know that Highpass technique but it's more about the lighting I think. When I render for 4K rendering it has his edges sharp enough but still got that blurry feel.
For example: Juraj Talcik in this project: https://www.behance.net/gallery/10048371/Parisian-apartment-by-Jessica-Vedel has really soft lighting and still images got that sharp feel.
I don't know, maybe I'm just oversensitive...
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Or maybe he just sharpened them a bit in post :)
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Or maybe he just sharpened them a bit in post :)
I never in my life did that to a render :- ) I only sharpen my photography.
To OP:
I am not sure if you mean more the "Haze" (from window glow) since you mention lighting, or Antialiasing, which does seem fine. It might be just that this particular angle gives such a feeling, but there might be no technical shortcoming.
Anyway, I personally, find anything less than 2.5k res soft. Which is why I render often pretty big renders, 5-8k, with soft (2-3px AA filter), which I keep in original resolution for printing, and downsample to 2k for Web&Social Media, which gives ultimately much nicer AA& Detail as if I rendered 2k originally. This might seem overkill for some, but for me it's utilitarian since I will need to high-res for nice print anyway.
I usually downsample using bicubic smooth, but our web I did exception and sharpened using bicubic sharpen, so I have 2.5k in sharpened state. You can see here : http://talcikdemovicova.com/classic-apartment-by-jessica-vedel/
Some few ideas:
1) Say no to high-pass. Never ever for archviz, it's the ugliest form of sharpening, it has very "thick" effect.
2)If you render anything under 2.5k, keep 1.5px Filter. Anything else might be too blurry.
2) Did you do denoising ? That can contribute a lot. I use denoising only for rather clean images, like under 2.5perc. of noise ratio. And even then, no more than 0.4 Blending.
3)Bump mapping. This is problematic with Corona, because too much will give you terminator artifacts, but too little will create unnaturally smooth surface. Everything has bump.
4)Texture filtering. Default 3dsMax is problematic. I am not sure if the CoronaBitmap is too much better...didn't do extensive test. But when you can, use the lowest (0.01) possible filtering. Even for bump, unless it gives you Terminator. Then write bug report, because we really need to get rid of it :- ).
5) Post-production that keeps local contrast. This can be done by few methods, we need the blacks to be black, not overall s-curve. Filmic mapping has "shadow richness" parameter that boosts blacks, CameraRaw has selective blacks, etc.
..
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Some few ideas:
1) Say no to high-pass. Never ever for archviz, it's the ugliest form of sharpening, it has very "thick" effect.
2)If you render anything under 2.5k, keep 1.5px Filter. Anything else might be too blurry.
2) Did you do denoising ? That can contribute a lot. I use denoising only for rather clean images, like under 2.5perc. of noise ratio. And even then, no more than 0.4 Blending.
3)Bump mapping. This is problematic with Corona, because too much will give you terminator artifacts, but too little will create unnaturally smooth surface. Everything has bump.
4)Texture filtering. Default 3dsMax is problematic. I am not sure if the CoronaBitmap is too much better...didn't do extensive test. But when you can, use the lowest (0.01) possible filtering. Even for bump, unless it gives you Terminator. Then write bug report, because we really need to get rid of it :- ).
5) Post-production that keeps local contrast. This can be done by few methods, we need the blacks to be black, not overall s-curve. Filmic mapping has "shadow richness" parameter that boosts blacks, CameraRaw has selective blacks, etc.
Thank you for this, Juraj.
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@Majeranek,
You can try lowering the image filter width down to something like 1,5, but probably not lower. (system > frame buffer > image filter > width)
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@Juraj_Talcik
Thanks for your answer.
Yes, I meant "haze"
1) I'm only using High-Pass, together with Chromatic Aberration added in ArionFX. This way I can regain some of the sharpness lost there. I use it on "Soft Light" blending mode and with about 25-50% opacity.
2) I need to remember that.
2) I used denosing but only 0.1
3) Bump mapping is one of my worst nightmares in Corona. I'm always struggling with setting right value. Sometimes 0,01 is too much and another 1 is not enough. Weird thing...
4) Maybe that's a thing. Most of the time I'm using values between 1,0 and 0,1.
5) I think that it can be second major source of my problem. I'm used to doing some simple corrections with "Brightness and Contrast", "Curves" and some "Color Lookup", so probably when I'm boosting up image to be lighter then that "Haze" comes out.
@maru
I've tried to but it only gave me problems with AA.
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Sometimes 0,01 is too much and another 1 is not enough. Weird thing...
Yeah I don't get this either sometimes :- ) I never get the bump I want on micro-level (fabrics), anything else is fine. The way filtering works is largely affected by resolution at which you see it, which is finicky to deal with.
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There is no need to lower filter radius.
option 1 - render 4k
option 2 - tweak contrast in post
And most definetly do not use sharpen.
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I disagree with the sentiment of lowering image filter being a necessarily bad idea. Just for funsies, try just turning the image filter off. This way a sample does not have a 2 px influence when being rasterized, but will only affect the pixel it samples. This will sharpen it, without "actually" sharpening.
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@Juraj_Talcik
What kind of software are you using to achieve that filmic mapping and local contrasts?
Most of the time I'm using ArionFX for 32bit .exr files and then some simple adjustments.
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@Juraj_Talcik
What kind of software are you using to achieve that filmic mapping and local contrasts?
Most of the time I'm using ArionFX for 32bit .exr files and then some simple adjustments.
I didn't like Arion too much, I use VFB+ plugin. Also, I don't need to wait for post-production or keep doing PS tests to see how it's gonna look. I like my framebuffer to show good looking image, easier to work with for me.
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Too bad there isn't anything comparable for C4D...
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Do you think this will work well even for video ?
I mean, traditionaly film rendering need to be blurrier than static images.
Red cameras for example have a low pass filter before the sensor (basically a glass plate to make the image less sharp) to eliminate moire and other artifacts given by too sharp pictures which in motion tend to flicker and stand out.
Some started to take out that low pass plate to have sharper images from the red camera.
I disagree with the sentiment of lowering image filter being a necessarily bad idea. Just for funsies, try just turning the image filter off. This way a sample does not have a 2 px influence when being rasterized, but will only affect the pixel it samples. This will sharpen it, without "actually" sharpening.
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Do you think this will work well even for video ?
I mean, traditionally film rendering need to be blurrier than static images.
Red cameras for example have a low pass filter before the sensor (basically a glass plate to make the image less sharp) to eliminate moire and other artifacts given by too sharp pictures which in motion tend to flicker and stand out.
Some started to take out that low pass plate to have sharper images from the red camera.
If moire happens, you will not cure it by giving samples a higher radius influence. You can only make it less obvious. The only way to truly get rid of moire is to increase resolution. Yes, no image filter works for video no problem, but it does give a less realistic feel. Video does not, by any stretch of the imagination, need to be more blurry. That's bad info. Besides compression already heavily scratching sharpness, the likes of V-Ray's Video filter will always be a mystery for me and a relic of past times, where Renderes out put a 768×576 NTSC resolution image and had to be blurred to a pulpy mess to be intune with TV images.
The thing is, no camera in the world can deliver the sharpness of a mathematically perfect 1 pixel - 1 sample of a renderer, so we intentionally let samples have a larger than 1 to 1 influence when rasterizing to make it more realistic and in-tune with real images.
All of the options above are valid. However, one thing is debatable: Sharpening a mathematically perfect representation of geometry. If you sharpen, you throw out the window the work, that has gone into the subtle differences to make the image seem more real. (unless you do it for artistic effect) So before anyone sharpens, take out the filter of the renderer first.
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technical sidenote: the "1 sample influence 1 pixel" "ideal" thing is also incorrect when rendering - because even rendering into image with finite resolution can be viewed as applying a filter on reality and can lead to artifacts such as moire. And you need to compensate that with another filter the way Corona does it
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rendering into image with finite resolution can be viewed as applying a filter on reality
Damn, that's some deep philosophy we got into.
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I know that some people use a highpass in photoshop on overlay to try and sharpen up images. I'm not a fan of sharpening images that often but maybe it could help you?
attached a quick copy of your image with the highpass over the top.
Highpass on softlight and or hardlight with different opacity's is used a lot for print 3D.