exterior lighting approach

[SgWRX]

i've just been playing with lighting exterior. has anyone used this approach with MR - 1 mr omni with an ambient-occlusion light shader set to ambient only (maybe the shader overrides that). and 1 mr spot/directional with a light-infinite base shader.

 

this is in response to my getting frustrated over the fact that materials in the material editor need to be extremely dark (unviewable) using mrsun/mrsky at my current skill level. frustration=learning opportunity

[Dave Buckley]

try to continue using the mrsun and mr sky

 

you should then be using the mrphotographic exposure control if you are unsure of how to use this then just use the preset for outdoor daylight

 

then you will need final gather turned on use a preset of medium (neve go higher or times will be far beyond worth it)

 

if the materials are still to dark or the scene in general is too dark then go back into the exposure controls and lower the EV value (you can find it under the drop down list where you selected outdoor daylight preset)

 

also in the exposure controls you will probably find that you need to increase the shadows value to around 0.6 - 1.0 in order to get some more contrast in the scene.

 

if the materials still need to be really dark then i am guessing you have got the gamma settings at default. if this is the case then go back into the exposure controls and you will find a gamma settings button, click it and enable the checkbox next to gamma correction to turn it on, then change the gamma value to around 2.2, and also the input value to around 2.2, hit ok, and then give the scene a render

 

 

also post some screenshots of your settings so that i can try and pick up other areas where you may be going wrong.

 

post exposure settings, render settings

 

but that should really be everything you need, and don't do what i have done for a year and wonder why your renders don't look like the professionals. i have been told numerous occasions that investing in photoshop is the answer to livening up your renders and believe me it does.

 

anyway let me know how you get on with the settings i have given you and hope it helps, it should be a good start for you and you can tweak the values i have given you until it looks good for you

[Macer]

Yep, as Dave said - look into your gamma setup. 2.2 is the way forward...

[SgWRX]

thanks. i'm using max 9 so i don't have the photographic exp ctl. i will have to wait until next year to get it, then probably a subscription. that may end this conversation. attached are 3 images. mrSpot and mrOmni. granted, the white sphere is blown out, but sometimes... then default mrSun/Sky with final gather draft. third, mrSun/Sky with 65 brightness (default) and contrast 95. contrast helps, but there's an obvious lack of whiteness to the trim around the lighter shaded building. i do agree, there's more a realness to the mrsun/sky with the contrast cranked up render. but then i loose brightness under the patio too.

 

after comparing these renders, i think i just realized something, exposure control prevents you from blowing out your highlights, which i would think contrast would allow you to do. mid-tones and brightness allow for blowing highlights, but they also do the same thing imo, and just brighten the scene overall as opposed to allowing you to change the tone curve.

 

i'm about to get a couple of modules from mentalboutmax that have this subject in them. overall i'm probably beating my head against the wall. i'd like try out the photographic control. maybe download the demo program.

 

anyway... there's trade offs anyway you look at it.

 

the grass, now that's a blend of bitmaps. everything is is a noise or tiles etc...with the colors from the color picker.

 

i've gone over gamma settings a several times over the last several months (or longer) and that hasn't gotten me anywhere. i tend to slam my head against the wall until i learn something new. ha!

 

(mr omni & spot)

 

 

(actual mrsun/sky with fg, contrast 100)

 

 

(standard daylight system with mr physical sky background, contrast 100)

 

 

(standard daylight with default exp cntl settings and mr physical sky)

Edited September 2, 2008 by SgWRX

[Crazy Homeless Guy]

the second image looks the best. the the first looks faked, and the third is under-exposed.

[SandmanNinja]

There's a GOOD THREAD here that pretty much covers Gamma.

 

Here are my notes from that thread - change 1.8 to 2.2 if you're in that school of thought:

The gamma correction depends on the file format that I'm saving to?

 

So:

If I save to a JPG, TIF, BMP, any-8-bit-format, set OUTPUT GAMMA to 1.8

If I save to a HDR, EXR, or any 32-bit format, set OUTPUT GAMMA to 1.0

 

Hope I can wrap my head around this.

 

[time passes - experiments performed]

 

Okay - I think I finally get it.

I click Customise -> Preferences -> Gamma/Lut -> set gamma input and output both to 1.0

I click Render -> Renderer tab -> Frame Buffer set to 32-bit

I did a very basic render with a HDRI and a primitive.

 

If I set the OUTPUT GAMMA to 1.0 and save it as a HDR, then it looks just like it does in 3DS.

 

JUST CHANGING THE FILETYPE TO JPG yields a very dark image - wrong gamma.

 

If I set the OUTPUT GAMMA to 1.8 and save it as a JPG, then it looks just like it does in 3DS.

 

So, I need to adjust my OUTPUT GAMMA according to what my file type is going to be.

 

[SgWRX]

YIKES! ugh, the 2nd image originally in the post was NOT mrsun/sky it was in fact just regular daylight system. i forgot to switch to mrsun/sky. i just opened that scene again and discovered that. so i added the acutal mrsun/sky render, but also left the standard daylight system.

 

the order is this:

 

1. mr omni and spot (no fg, no exp control)

2. (updated) mr sun/sky with fg and 100 on the contrast

3. (accident) standard daylight system, however with a mr physical sky, contrast 100

4. (accident) standard daylight system, mr phys sky and contrast at 55.

 

sorry... it's been one of those of days.

[SgWRX]

well, anyway. what's funny is, autodesk has a display gamma. that contradicts the gamma that my display is already calibrated to, so i'm doubling up the gamma. then, it's not reading the gamma saved in a "bitmap" (jpg, png whatever image you choose to use a map).

 

ultimately, they need to be able to read a monitor profile, read other color profiles (aRGB, prophoto, sRGB, ntsc) and save rendered images in whatever profiles are installed. heck, then you could print right from the rendered frame window using a paper profile. that would put them on the right track for color matching.

 

i've got a friend who's loaded the demo version of max2009. i'm going over there to play with it tomorrow.

 

thanks for everyone's input (again. b/c i've seen and read a lot on this).

[SgWRX]

i re-read the "note on gamma" in the mental ray arch&design manual and i think something clicked. at least so far as to let me match colors in the material editor and color selectors and my mrsun/sky rendered frame window. seems to get pretty close except for the mrsun color and mrsky color changing them a bit which can be controlled with saturation controls in those components. (to retain the blue sky, i just use the mr physical sky and unlink it from the mrsky).

 

and saving the rendered frame window as a jpg, i have to override the gamma setting and use 2.2 instead of 1.0. it will for the most part look accurate in a windows environment.

 

it's also interesting to note how the a&d materials change in color value depending on other properties such as reflectivity. for example a matte finish shows nice and saturated dark colors whereas a glossy finish will reflect a lot of environment light and appear lighter and more blue.

 

in the case of trying to take a an RGB value from a paint mfg. and applying it to a material, it still falls short. for example, 165,56,48, still looks too bright or 'faded'. perhaps there is a way around this by loading up the color in a program and tweaking the gamma then using a color picker to read the RGB values.

 

hm. well, at least i'm closer and have a better understanding.