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 Taming The Dimensions
Marie Brown
Marie Brown
Marie Brown is an experienced writer and a less experienced 3D artist. Her interests include creating 3D content, experimenting with different software and render engines, and learning how to make 3D imagery so fabulous that no one will question whether it's art or not.

Playing With Render Settings: Pixel Filters

 
May 26th, 2014 by Marie Brown

When I first started using DAZ Studio, I freely confess that render settings meant nothing to me. I’d used Bryce casually for years, but generally left it on its default render settings, because I was kind of afraid to change anything lest I break the program. But using DAZ Studio forced me to get over that silly fear in a hurry, because the default render settings in Studio are pretty lousy. Here’s an example render using the default settings:

olympia_daz_default DAZ Default Settings

Max Ray Trace Depth: 1

Pixel Samples (X,Y): 4

Shadow Samples: 10

Gain: 1

Gamma Correction: Off

Gamma: 1

Shading Rate: 2

Pixel Filter: Sinc

Pixel Filter Width (X,Y): 6

Not the greatest image ever, I think you’ll agree. The default settings produce very blah and disappointing renders, especially when you’ve been looking through galleries and seeing all the amazing things people can do with this free program (and all the paid content they lure you into buying). After doing a bit of research into why my renders looked so bad compared to everyone else’s, I found out all sorts of interesting things about ray tracing, pixel and shadow samples, and shading rates. Those are the basic settings that need to change to produce a decent render. So here’s an example of a render done with my preferred final settings:

olympia_my_defaultMy  Default Settings

Max Ray Trace Depth: 4

Pixel Samples (X,Y): 12

Shadow Samples: 32

Gain: 1

Gamma Correction: On

Gamma: 1

Shading Rate: 0.1

Pixel Filter: Sinc

Pixel Filter Width (X,Y): 6

Olympia now looks sharper, more in focus, not blown out. Her hair looks better, and the details on her dress are more visible. Still not absolutely fabulous, but definitely getting better.

All right, there you have a baseline for this experiment. That last pair of settings, Pixel Filter and Pixel Filter Width, are what snagged my attention this time. I’ve messed around with pixel filters in LuxRender enough to know that they change the quality of the image, but not how or why. I’ve also ran across comments online that indicate using a pixel filter width higher than six is crazy, but again, I don’t know why. So here it goes.

Box Pixel Filter

olympia_boxYuck! She’s gone all blurry and out of focus. Okay, try again.

Triangle Pixel Filter

olympia_triangleOkay, not as bad, but still not nice and crisp like I want. Next one I have high hopes for, because I’ve used it in Bryce and been happy with it.

Catmull-Rom Pixel Filter

olympia_CR

Whew, she’s looking like herself again. Okay, one more try, and I know this one will be blurry, simply because of its name.

Gaussian Pixel Filter

olympia_gaussian

Yep, more blur, although still not as bad as that box filter.

So, why do the box and triangle filters look so horrible? This entailed a bit of research. I went online and read up on pixel filters. A pixel filter turns out to be the calculation used to determine what each rendered pixel filter will look like. If you want the technical details, sorry, you’re on your own. Math makes my head hurt. But take the box filter for an example. It looks at a single pixel, then it takes all the pixels around that one in a box shape and calculates an average of all the values. Voila! Now I understand why the image is so blurry! Because the filter is looking at its surroundings and averaging them out, resulting in mush.

Now how to fix the mush problem? There has to be a way, otherwise nobody would ever use the box filter for anything. Hmm… calculates surrounding pixels… What about pixel filter width? Aha! That tells the render engine how many pixels to look at. So, if I’m right, modifying the pixel filter width will transform the box filter into something usable for purposes other than producing a nice blurry background to composite with another image and simulate depth of field, which is about the only use I can think of for something that blurry. So. Here we go.

Box Filter, Width 3

olympia_3x3_box

That’s it, then. There’s a visible improvement in the image, just by changing the pixel filter width.

Box Filter, Width 1

olympia_1x1_box

There you have it, folks. Olympia is back to looking like herself again.  Just to make certain, I tried the triangle filter out with different filter widths, and the same result happened.

Hopefully you learned something from my little experiments. I know I sure did. Happy rendering!

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