Rotring Pen Renders

[swisscad]

Comments and critics welcomed

[Budy]

Re: Rotring Pen Renders

Cool ....why metal material like your's -me too- always jaggy :'( and your plane color is so bright.

[Paraglobal]

Re: Rotring Pen Renders

Hi

The first image seems a bit tool bright, but I like the renders.

Are you working with 2.2 gama? Your black seems lime my first renders with 1 gama.

Good work
Sergio Silva
www.Paraglobal-3d.com

[Travis Serio_cg]

Re: Rotring Pen Renders

Cool ....why metal material like your's -me too- always jaggy :'( and your plane color is so bright.

Turning on Sub Pixel will help that.

Nice renders! makes me want a mechanical pencil even though I just sit and break the lead in them >

[dalomar_cg]

Re: Rotring Pen Renders

The jaggedness is actually due to antialiasing of brighter pixels. V-Ray thinks of everything in float values, therefore colors are allowed to be brighter then white. When V-Ray has to compute antialiasing values it does so with those float values, so in between a value like 1.75 and .75 is 1.25, but that value is still brighter than white...hence the jaggedness.

The best way to get rid of those artifacts is do you're best to make sure you're colors aren't burned, or over bright. The other way is to use Clamp Output, which will limit the colors to just white nothing brighter. When using clamp output its best to also use subpixel mapping, as that is the most physically correct method when you clamp the output.

[Travis Serio_cg]

Re: Rotring Pen Renders

Damien. Am I correct in thinking that the only time you would need to disable clamp output would be for the creation of hdri images? I have my default visopt set to always enable clamp output and sub pixel which has always fixed the jagged edges problem, but I never knew if I was setting myself up for failure on other aspects like maybe a glowing surface here and there from luminosity.

[Micha_cg]

Re: Rotring Pen Renders

Most I don't use the "clamp output" because I like to use the framebuffer to fine adjust the color correction - black colors and simulation of an analog film curve (flat curve at the upper part to catch high contrasts).

The usage of the image sampler AA filter gaussian 1.3 .. 1.5 could help too. And render double size at lower noise quality and downsample is an other way.

I wish, the clamp output could be done at frame buffer level. Some months befor I ask here, but no answer yet. This jagged edges are realy a problem somtimes.
Or why not a special frame buffer filter, that add a blur at this high contrast jumps? This could look like a typical camera "glow" of Lens scattering.

[Travis Serio_cg]

Re: Rotring Pen Renders

Or why not a special frame buffer filter, that add a blur at this high contrast jumps? This could look like a typical camera "glow" of Lens scattering.

That would be a brilliant solution. I love the glow that metals have in photography. It's always been difficult to achieve without post processing.

[dalomar_cg]

Re: Rotring Pen Renders

There's nothing wrong with clamping the output if you don't need the information. In vfMax 1.5 the chaos group put in the ability to set the clamping point (ie have it at 1.5 or 2 instead of only 1) which is really the best of both worlds. I hope it will get in the SR, but I'll have to harass Joe a little more.

[Micha_cg]

Re: Rotring Pen Renders

;D Oh, yes please.

[dalomar_cg]

Re: Rotring Pen Renders

Yea very useful...as I said I'll be bugging Joe

[swisscad]

Re: Rotring Pen Renders

hi
well I'm lost in this conversation:
Travis: Where do you turn on Sub Pixel..?
What does "Clamp Out" mean or do... I see where to enable and disable but I don't understand what it does or mean...
@paraglobal:Are you working with 2.2 gama? Your black seems lime my first renders with 1 gama. I have no idea, what does gama do anyway?

Thanks

[dalomar_cg]

Re: Rotring Pen Renders

Sub Pixel Mapping and Clamp Output are both in the Color Mapping Rollout. I'll explain Clamp Output first, since its concept will make more sense when explaining Sub Pixel mapping.

When V-ray calculates and image, it does so with float values which allow colors to go beyond, or brighter than white (white in float is 1, so colors can be more that 1...like 1.4 or 3). This is potentially a lot of information that is "unnecessary", since our monitors or paper cannot display these colors. Also, vray will take longer to calculate brighter pixels that it will to calculate darker ones (this goes back to importance sampling...another explanation), so the brighter values have the potential to make a rendering take much longer. Clamping the output tells V-Ray that you don't want all of that overbright information, so V-Ray stops calculating it. This makes things like AA much smoother and also most calculations on the brighter parts of the image a little quicker.

Sub-Pixel Mapping basically looks at the individual samples of an image rather than the resulting pixel (ie the parts rather than the whole). Usually its better to leave this off, but with clamp output on, it is more efficient to have it on, and here's why. When you're clamping the output, you don't want that bright information and part of the reason is to decrease render time. With sub pixel mapping off, v-ray will only worry about whether a pixel is too bright, after all of the values have been calculated. In that case, you haven't saved too much time really since those values were still calculated to their full extent. With sub pixel mapping on, v-ray will understand the brightness of each sample and check to see how bright they are. As soon as a sample pushes the value of that pixel beyond white, then v-ray cuts off those calculations, since the information that they would add to the pixel would essentially be discarded anyway. So subpixel mapping is really more of a way to save time when using clamp output.

On to the other white elephant...Gamma (gamma correction is on by default, so if you haven't directly messed with it, then you're probably fine and you can read along if you'd like)
Gamma is referring to how colors are displayed on our monitors. Our monitors don't actually respond or display colors linearly (linear meaning essentially a direct relationship between the color a monitor is told to display and what it actually displays). Monitors have a Gamma response curves to colors, meaning that they actually darken the middle range of color values. This is known and accounted for, so pretty much everything on your screen has been corrected for this, so that you don't have to worry about it at all. Along comes V-Ray, which does all its calculations linearly. What happens is that when it does all of its calculations, v-ray doesn't take into account how the final image will be displayed. Thus a rendering is linear, but is displayed with the monitor's gamma response...leading to an image that has midtones that appear darker than what they really are. So if we tell v-ray that our image needs to be corrected for our monitors, then we won't have this problem...this is the Gamma 2.2 thing. One thing that we'll find when we do correct the output is that all of our colors and textures are washed out. This is because we are picking our colors and editing our textures in gamma corrected space, and when we correct the v-ray output we actually wind up correcting them again. We can get around this by applying an inverse gamma correction and every thing will look fine and dandy.

So all of that mumbo jumbo, and what does that mean to you. Well, all of the gamma correction is at the bottom right corner of the Global Switches rollout. We've set the defaults up so that it takes care of all of the gamma correction for you, so you should see the input and output gamma values at 2.2 as well as Correct Colors and Correct LDR textures enable. If you've got that, then you're fine, but if you import some of the older visopts, they may not have those values set. If you see a gamma of 1 and the two correction boxes unchecked, then you're not applying any gamma correction. Hopefully this makes sense. Below are two links...the first is a tutorial made by Gijs which is old, so its implementation of gamma correction is now obsolete, but his explanation of what it is and how it works is still good. The second is wikipedia's gamma page

http://asgvis.com/index.php?option=c...d=24&Itemid=55
http://en.wikipedia.org/wiki/Gamma_correction

[Micha_cg]

Re: Rotring Pen Renders

Also important for black materials, be careful with extrem values like 0. Most it is better to use 5 .. 11 for the lowest black. Black 0 means, that all light is absorbed, something like a black hole.

[fam_ark]

Re: Rotring Pen Renders

Hello,

really nice and clean renderings!

I like them!

Espacelly the second one with depth of field...

greetings

Jonas