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Home Jeff's Blog Let's help put an end to our low contrast renders!
Let's help put an end to our low contrast renders! PDF Print E-mail
Written by Jeff Patton   
Tuesday, 03 June 2008 13:44

Maybe it's just me, but it seems there's a movement towards low contrast, no burnt/overbright areas in renders these days. I know I've been guilty of it to some extent. Why? Well I think LWF has a lot to do with it.

For the longest time a lot of us created images with incorrect gamma settings. We often had too much contrast in our renders. Then this "LWF Revolution" came around and now IMHO the pendulum has swung the opposite direction. Now it's far more common to have little to no contrast in our renders.

So how do I get more contrast in my LWF renders? Well, if you're using the mr photographic exposure control a lot of that contrast will come from three simple settings: Highlights (Burn), Midtones, and Shadows.

Examples:

(click image to enlarge)
Alternate
Notice how the "Highlights (Burn)" value alters the output

(click image to enlarge)
alternate
Notice how the "Shadows" value alters the output

(click image to enlarge)
Alternante Text
Notice how the "Midtones" value alters the output

Also, if I've said it once, I've said it a thousand times...studying photography can really help us as 3d artists in our quest to recreate realism. Now I'm certainly not saying "go out right now and invest in an expensive DSLR camera". I'm just saying you may find it really beneficial to at least read some of the free photography tutorials/information online. And of course study photographs of lighting conditions (and textures), and then try to recreate that in your 3d application of choice.

Let's take a look at some photos now. These (and many other) reference images can be found on a quick Google image search for "exterior".

(click image to enlarge)
Alternate Text
Notice the warm/soft sun color in this image? Also pay attention to the overbright/burnt out sky and overall amount of contrast in the photo.

(click image to enlarge)
http://jeffpatton.net/Blog-images/Photo02-thb.jpg
High contrast again in this reference photo. Also some subtle over exposed/burnt highlights. Again, you can feel the warmth of the sun here which contrasts the cool blue sky.

(click image to enlarge)
http://jeffpatton.net/Blog-images/Photo03-thb.jpg
Burnt highlights again here...also notice the cool blue indirect lighting.

(click image to enlarge)
http://jeffpatton.net/Blog-images/Photo04-thb.jpg
Ahhhh, lens flare! ...I also keep this one for the pavement material reference. Notice the blue shadows & over exposed sky.

(click image to enlarge)
http://jeffpatton.net/Blog-images/Photo05-thb.jpg
I thought this was an excellent glass reference photo. And of course it's a good reference for soft indirect lighting. I also like the warm bounced light at the entrance. Again, the sky is blown out/over exposed.

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Joseph Harford wrote on September 25, 2008
 
Title: Great post
A good post, something i've been noticing around a lot recently.

I have one question I hope you can answer. -

Does the preview window in the exposure control in max 2009 include the gamma adjustments? When I alter my preview to be correct, the gamma in the rendered image( full size ) is much brighter.
Of course this could be becuase i've screwed up on importing my textures gamma correction. But is this so?

Thanks
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Jeff Patton wrote on September 25, 2008
 
Title: ...
Yes, the render preview window can look different from the actual render if you're using an adjusted gamma setting (like me). I don't use that preview window for this, and a few other reasons...like it's just too darn small.
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Alessio Erioli wrote on May 28, 2010
 
Title: pics don't show
Hi all,

I read this article first more than one years ago and I have to thank you for its total usefulness!

I looked for it once again but this time I'm not able to see the pictures. Is it just me experiencing this issue?

Thank you again for the helpful tips.

Regards,

Alessio
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Jeff Patton wrote on May 28, 2010
 
Title: ...
I think I fixed it. Be sure to refresh the page in your browser (F5). The other day I had enabled leech protection on my site and while I allowed mrmaterials.com and other CG sites access for some reason it still didn't allow the images through.
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Ricardo Arrifano wrote on January 05, 2011
 
Title: Outdoor scenes average values you use Jeff
Hi Jeff, thank you so much for this tip, i believe its the approach i needed to solve some "washed out" renders...i never thought of messing around with those 3 settings.

I've been doing some tests but couldn't find til now the ideal values for an outdoor scene i'm creating.

I would like to ask you something:

- each time you have a brand new project, do you change the values for each case?
- what values do you use the most for outdoor rendering (i know there's not a straight forward answer)?

Thank you once again and keep on coming with these smart tips n'tricks!

Cheers,

Ricardo Arrifano
Architect
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Jeff Patton wrote on January 06, 2011
 
Title: ...
"each time you have a brand new project, do you change the values for each case?" - I have several lighting templates that I typically start with:
Day_WarmMorning, Day_CoolMorning, Day_Cloudy, Day_WarmAfternoon, Day_CoolAfternoon, and Evening.

Sometimes I'll need to use those as a starting point, sometimes I can just use the template as is.

"what values do you use the most for outdoor rendering (i know there's not a straight forward answer)?" - I think this config probably sees the most usage for daylight exterior type scenes:

EV = 14
Highlights/Burn = 0.1
Midtones = 0.9
Shadows = 0.5
Color Saturation = 1.1
Whitepoint = 5400 Kelvin
Vignetting = 4.0

Of course as you said there isn't a magic bullet/single best exposure setting and I typically always make post adjustments.
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Ricardo Arrifano wrote on January 14, 2011
 
Title: HDRI issue
Jeff, thanks for the previous tip on the values, i rendered a test image and i'm very pleased with the results i got with daylight system (and after some PS curves corrections). Here it is: http://img407.imageshack.us/im...estxft.jpg

Now i wish to give a step forward with HDRI.
I downloaded your tutorial on Gnomon's website and understood the entire workflow, i haven't seen any other tutorial on the web so precise and well explained, so i thank you for that.

I tested your settings but i've got a problem i can't seem to solve:

- the HDRI used on the skylight (the other one's on the environment map)is not iluminating the scene objects, the difuse color of each material renders completely black except the reflections, that somehow are visible.

I set up a simple test scene using exactly the same settings (one skylight, a sphere with A&D orange color and two HDRI's on the environment and skylight maps), but i still can understand what am i doing wrong.

I would like to ask you to take a look at the screenshot i took from the test scene, i think it's self explanatory and it happens with the scene i showed you before: http://img808.imageshack.us/im...gblack.jpg

Thank you in advance on any hint you might give at such long distance.

Cheers,

Ricardo Arrifano
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Ricardo Arrifano wrote on January 16, 2011
 
Title: ...
The problem's solved, i got a hint from Russell to set the physical scale to unitless and bump the value to its maximum (200000,00)...and it worked, the difuse colors/maps were finally visible!

Thanks again Russell! =)

Screenshot: http://img716.imageshack.us/im...svalue.jpg
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Russell L Thomas wrote on January 16, 2011
 
Title: Glad to Help
Glad to help with an actual problem, usually the question is how do I install the material! LOL Looks good my friend!

In addition when you ask the question at the 3DA forums, I am more likely to see it and answer.

Cheers!

Russell
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