[3dtrialpractice]

I've seen some nice Mxi emmiter renders here on the forum, but I have yet to see a MXi as emmiter that gives correct shadows and portrays the Brights of the image into the render. What I mean is that all the Mxi renders posted have very soft shadows, great for that cloudy overcast look, or indoor difffuse lighting, but bad for harsh light scene setups.

I shoot my own hdri's and always have had good results in mental ray, yet when I try to convert the Hdri to mxi it looks like its converted great untill the render, and then there's a clear loss of the light sources intensity in respect to shadows, now reflections look great, but the shadows are lost an become soft.

heres and example:




this image is rendered in maxwell and mental ray, as you can see the maxwell reflections look good, but this hdri I shot in the Harsh midDay light and the render looks very ovrcast, the Mental ray render had no problem rendering out the matching harsh shadows of the sun.

So first I thiough ok, maybe I jsut messed up the conversion from hdri to mxi,, in respect to the intensity, fstop and shutter speed, and yes I recorded all this during the shoot and reinput it into the mxi creatiion inputs in the maxwell viewer.

so I went and reconverted the Hdri to mxi, using different Intensity and even tried different shutterspeed values,

in the brightest of these the intensity was 10,000 very high, but still no harsh shadows.

My next thought was that i screwed up my hdri exposures,, so I went out on my parging garage and reShot a new set of exposures, this time getting more exposures in the underexposed ranges to capture the sun at more stops
and here ar the results..



In this set, you can see a more Directional look to the shadows, but they still look nothing as harsh as they are in the real scene...
again I did a test on lots of different combos of Intensities and Shutterspeed setting in creating the mxi...

here is a image of the spherical map so you can see the harsh shadows on the ground from the cars and the walls...




so can anyone fill me in.
to me this is a clear shortcoming on mxi dynamic range preservation, since mental ray had no problem with any of the Hdri images in creating the harsh shadows of the scene.

so what am I doing wrong, or what should I understand that I dont, anyone with any success in recreating a harsh sunlight setup with mxi?


The main point of rendering the scene with the hdri is to get the exact light situation of that time, something that is tought to even match with physical sky due to its limits at this time, plus with clipmaps broken I can get the surrounding in unless its composited, and compositing it with physical sky brings up its own difficulties, such as trying to match the colors of the physical sky to the colors of the sky and seperating it, color matching to the surrounding trees, clouds, powerlines, etc.

anyone have any comment for me,, did I miss something crucial?
has anyone gottten correct harsh shadows from mxi emmiters?

thanks in advance, I would love to completely render with maxwell instead of having to render some shots in maxwell while all my outdoor hdri scenes in mentalray, i love how maxwell treats colors, bump and all properties of shaders, so this is the cause of my frustration.

love to be rendereding 100% maxwell.

thanks again,
luke

[Mihai]

In the mental ray version did you use any other light sources besides the hdri? Because it looks like the sharp shadow does not correspond with the sun position and also it looks like you have two 'suns' in the reflection.

[true]

I have the same problems!

I always feel the convertion of the hdri to mxi will make the hdri loss information. I tried so many test too, but it is difficult to tell from the eyes.

I only realize once you convert the hdri to mxi, it will stay in that particular exposure, no matter if later change the shutter speed of fstop of the camera, it will not affect the mxi ....

I am so confuse too, I hope someone can kindly explain if they know.

Finally one more question, so is a high resolution image better than a small hdri for converting to mxi???

Thanks thanks

[andronikos916]

hmmm...

under tesrting...

cy later,
Andronikos

[3dtrialpractice]

In the mental ray version did you use any other light sources besides the hdri? Because it looks like the sharp shadow does not correspond with the sun position and also it looks like you have two 'suns' in the reflection.

yes, your right, there is a second spec on the mental ray, I think its from not turning off default light in maya on this one, but that default light isnt casting shadows, the shadows in the mental ray scene are falling in the same direction as the shadows in the scene though,

Im gonna edit this post, to make it more organised and show screen caps of my mxi creation settings next to each render, and I have updated images of the mental ray renders too to be more clear.

Its gonna take me a few days to update it, probably over the weekend, since i need to get other projets finihsed this week.

Also I think I can creat a "fake" for this mxi scen, basically, replace the face on the sphere where the sun lies in the image and replace that face with a new face (or maybe a polygon circle) with an B type emmiter at a high intensity to fake sunlight in the scene while keeping the beauty of the mxi reflections from the mxi emmiter dome.

-thanks for noticing, and Ill post a update in the weekend.

-Luke



-------------------------------------------------------------------------------
quick Edit

ok I quickly rendered some more Mental ray renders,, and This time, I made sure the maya default light was off, so no lights exept the hdri.

This is a mental ray render of the Parking garage Hdri from the second set of maxwell renders,, will do alot more on this on the weekend.

[jep]

mihai - great eye!

3drtrial - thanks for bringing this up... I've been looking for a solution for this for a while - let me know what you find. I did the same thing... meaning, tried an HDR render in Mental Ray to see if I'd get the "sourcey" shadows... man, I just like the wya Maxwell looks so much more than mental ray - I', jaded!

let me know if you a solution - I'll do the same...

Keep up the good work,
Jep

[Mihai]

Could it have to do with the way the emitting sphere is set up in Maxwell? The size of it I mean. Perhaps Maxwell is treating it as a huge area light, while the environment setup in Mental Ray is specifically for IBL, no sphere tricks hence no giant area light fading the shadows.

So looks like Maxwell needs a dedicated mxi environment setup.

[3dtrialpractice]

Could it have to do with the way the emitting sphere is set up in Maxwell? The size of it I mean. Perhaps Maxwell is treating it as a huge area light, while the environment setup in Mental Ray is specifically for IBL, no sphere tricks hence no giant area light fading the shadows.

So looks like Maxwell needs a dedicated mxi environment setup.

Right, thats a great point,
Its what it looks like, that it takes it in as an area light, emmiting from all around, becasue oll the faces are emmiters, with the same mxi map emmiting at the specified intensity, so you get the great richness of the colors from all the blues in the sky, and the various other hues of the env, but all these great colors emmited tend to fade the shadows out.

and this reminds me of a wish list topic, of an infinte horizon like brazil, maybe as part of like you said a dedicated environment setup,
in fact maxwell kinda does have this just early, the sky dome.
If I understand you right, your almost saying, plug the mxi file not on a geometry in the scen,hence sphere, but plug the mxi file directly into maxwell's existing sky dome.

thanks for those thoughts,,

i now understand..
and what also is a big factor, Sunlight is Parrallel light, while this geo dome approach only casts dome lights that converge not parrallel.

-Luke

[3dtrialpractice]

Could it have to do with the way the emitting sphere is set up in Maxwell? The size of it I mean. Perhaps Maxwell is treating it as a huge area light, while the environment setup in Mental Ray is specifically for IBL, no sphere tricks hence no giant area light fading the shadows.

So looks like Maxwell needs a dedicated mxi environment setup.

THANKS you For B***h Slapin ME into thinking about this clearly!
after reading your post i dint want to wait to the weekend, i needed to make sure now!

your awsome, ,
Here is THE NOW SUCCESSFULL RENDER of harsh shadows in maxwell with MXI emmiter on poly dome --





ok this technique on these renders is quite a bit more noisy, but thats due to the poly count, now we can just optimise the geometry on the dome.

goodbye Mental ray,, HELLO MAXWELL your beautiful,,
Skreen caps of the mxi scene comming soon!

Basically, I thought, what makes parrallel light rays in maxwell?

duh,, Ye' 'OL Flashlight Technique!!!

So i mapped a poly sphere with a jopg of the mxi, saw where the sun was on the faces, Extruded , smoothed, and set back the faces, creating a "spike" in the Sphere, and that spike is where the sun is in my picture, only the paralel light rays from those emmitted faces escape the sun tunnel.

so it turns out, mxi's Do hold the dynamic range, its just a matter of implemintation.



-L

[3dtrialpractice]

screen shots of the Mxi "sun sphere"

Very very simple and not too poly efficent right now, but it does the job, now to optimise that geo!






-luke

[Jun In Gi]

nice result!
oh,i just have read this thread.
as you explain

creating a "spike" in the Sphere

in the quote, spike mean emitter object as separate one exclude mxi emitter you did hemi sphere? if yes, what object did you use? plain

[3dtrialpractice]

nice result!
oh,i just have read this thread.
as you explain

creating a "spike" in the Sphere

in the quote, spike mean emitter object as separate one exclude mxi emitter you did hemi sphere? if yes, what object did you use? plain

OHH!, great thanks for asking,

ya, the spike, is just the few vextexes of the sphere pulled back into a spike like in the screen cap above, and then I Extracted(w/ seperate) those pulled out face, so they are a sepret piece of geo, and then you assign it with a B type emmiter at a high intensity ie:10,000 or 100,000

so texture the spike with a Intense emmiter or an intense mxi map


now if you look into the sun spike then you shoud assing the spike with a lowlez but hiintensity mxi texture so that there wont be a seam where the sunspike tunnel starts on the sphere.

hope this is clear, Ill put together something else on this soon!
for now experiment with face count, and simplifying this geo sphere, so that render is as noise free as possible (less faces,faster noise cleans up)

happy maxwelling!

-Luke

[Jun In Gi]

i understood

thanks for the kind explain.

keep it up!

[Maya69]

thank pat

nice technique

but you don't directly capture intensity and color of light (sun)

i seach a technique for otain this




http://gl.ict.usc.edu/skyprobes/

this movie capture the intentity and strong of shadow produce by hdri sky cloud

i hope a maxwell render compute this ibl technique


but i repeat your technique is very good for hdri render env

thank you

[3dtrialpractice]

**This setup is obviously way too many polys for that spike,, It would work way better to extrude just the face there with the sun, I got a web of too may faces for that spike, so recreating that spike should only have 5 faces to it.

thank pat

http://gl.ict.usc.edu/skyprobes/

this movie capture the intentity and strong of shadow produce by hdri sky cloud

i hope a maxwell render compute this ibl technique


but i repeat your technique is very good for hdri render env

thank you

DUDE!
wow now THAT's exactly what I wanna acomplish!
Thats a great technique, and to do it with the video, brilliant!
http://gl.ict.usc.edu/skyprobes/skycapture_poster.mov

thanks for linking to this!
-Luke