I hope that v7...

[GeneCrucean]

I really hope that SI is updating the scene units for v7. I'm sure with all of the new ICE stuff this will really start to become important.

IMO, you know something is wrong when the gravity setting is set to 98.1 when gravity in the real world is 9.8. Or when everything that's stuck in there like Mental Ray has to have it's default units scaled to match XSI. Case in point: Take a look at the Physical Sun node and look at the multiplier. 1? This needs to be scaled to .01 for the correct scale every time you use it.

Is there any word on updating this unit stuff for v7?

[Zafar Iqbal]

Hear hear! Infinity +1

[Zac-Donald]

They claim it makes easier cause the user can have it been what ever they want? thats total bs, it'd be easier if you could seamlessly use different units of measurements together. Like type in 10cm for one objects height, then be able to use 5 ft for another just by typing it in, this way people wouldn't have to convert their units before going into xsi. (just make sure the user can define the default units he sees.)

[wurp]

I do agree that sometimes the scale can be a bit off, but keep in mind that physical values never quite work in CG, just because the gravity is 9.8 in real life doesnt mean a value like that would give you the results you want, even if the application was designed to work like in real life.

As for the physical sun node, that value has nothing to do with scene scale at all, it has been designed to work with a tonemapper that will take care of overbright values. If you find it doesn't work for your needs simply edit the SPDL.



I really hope that SI is updating the scene units for v7. I'm sure with all of the new ICE stuff this will really start to become important.

IMO, you know something is wrong when the gravity setting is set to 98.1 when gravity in the real world is 9.8. Or when everything that's stuck in there like Mental Ray has to have it's default units scaled to match XSI. Case in point: Take a look at the Physical Sun node and look at the multiplier. 1? This needs to be scaled to .01 for the correct scale every time you use it.

Is there any word on updating this unit stuff for v7?

[GeneCrucean]

I do agree that sometimes the scale can be a bit off, but keep in mind that physical values never quite work in CG, just because the gravity is 9.8 in real life doesnt mean a value like that would give you the results you want, even if the application was designed to work like in real life.
The point is that the real world scales would give you a good base to start things off at. Of course, if you want to create a unique effect... sure, bump the gravity up to 50 if you want, 1million, whatever. What's your point with this? Of course we need the flexibility to adjust the gravity amount, but do you disagree that it should at least be a physically correct number to start from?


As for the physical sun node, that value has nothing to do with scene scale at all, it has been designed to work with a tonemapper that will take care of overbright values. If you find it doesn't work for your needs simply edit the SPDL.
Can you show me how to do that? (trick question fyi)

I do. I edit a LOT of spdl's actually. Like default render options, and AO so that it works like it should. But this brings me to another bug (if you want to call it that). "Some" spdl's don't work well if you edit them. For eg. if you edit a soft_light so that the default settings are 0 umbra (like any real world light) and check shadows on. Now if you save a scene and open up that file on a machine with un-edited spdl's. It doesn't tag these settings as being changed and will use the default .75 umbra and no shadows. Fun times.

[wurp]

The point is that the real world scales would give you a good base to start things off at. Of course, if you want to create a unique effect... sure, bump the gravity up to 50 if you want, 1million, whatever. What's your point with this? Of course we need the flexibility to adjust the gravity amount, but do you disagree that it should at least be a physically correct number to start from?


My point is if a value is set to 9.8 or 0.25 or whatever it is doesn't really matter, I do agree that having default values that looks nice is a good idea but I don't really care what those values are, I simply adjust things until I'm happy, having the sliders range set to something reasonable is more important than physically correct values really.



Can you show me how to do that? (trick question fyi)


Add the "simple_tone_mapping" shader to your camera and play with the compression value, a tonemappers job is to basically make sure that a HDR image can be displayed on an 8bit monitor without too many blownout areas, sunlight is really strong and you might find that you want surfaces hit by direct sunlight to be almost blownout, hence the reason why the default value is set to 1.0.

[GeneCrucean]

I guess the "physical sun" is supposed to create toon lighting then ;)

http://www.genecrucean.com/misc/tone_mapping/



... just sayin

[wurp]

yes, thats true, the mia_photographic_exposure does a better job at this actually, it's the same method, just a different shader, I just tried it and it does indeed work, it doesn't give you that toon feel you showed.

1.0 might be a bit high, but the range is ok, with a tonemapper you might set it to something between 0.2 and 1 rather than 0.01, these are the values suggested by mental images and when you use the shaders correctly they do make sense.



I guess the "physical sun" is supposed to create toon lighting then ;)

http://www.genecrucean.com/misc/tone_mapping/



... just sayin

[Jesse]

I was under the impression that based on the simulation nodes and the size of objects like the camera and a spot light a single XSI Unit was 10 centimeters or a decimeter. Which makes perfect sense with the gravity at 98.1 units or 9.81 meters/second^2

*shrug* never had a problem with any scale issues when I assume this.

[pablo]

I never have problems with xsi units, but if the goal of Softimage is make new users from Maya/Max they need a real world unit to prevent all the problem that users have.

[nixx]

Like I 've said before in other discussions, if SI themselves suggest that 1 SI unit = 10cm, then the interface should reflect that.

The "assume whatever scale you want" excuse is in direct conflict with their own 1 SI = 10cm suggestion !

nick

[Zac-Donald]

if they say something they should stick to it, and it'd be nice if it'd auto convert to what units you set in the prefs.

[GeneCrucean]

yes, thats true, the mia_photographic_exposure does a better job at this actually, it's the same method, just a different shader, I just tried it and it does indeed work, it doesn't give you that toon feel you showed.

1.0 might be a bit high, but the range is ok, with a tonemapper you might set it to something between 0.2 and 1 rather than 0.01, these are the values suggested by mental images and when you use the shaders correctly they do make sense.

Yes mia_photographic_exposure does let you bring down the values enough so it's not blown out, but it's still wrong.

Here is a render of Maya's default settings (I'm not saying this is a good render btw ;) ):
http://www.genecrucean.com/misc/PS/MayaPS_Default.jpg


Here is a render of XSI's default settings (with mia_exposure_simple). Also note the sky and shadows:
http://www.genecrucean.com/misc/PS/XSIPS_Default.jpg


This is an XSI render with Maya's mia_exposure_simple settings:
http://www.genecrucean.com/misc/PS/XSIPS_MayaSettings.jpg


This is a render with mia_exposure_photographic:
http://www.genecrucean.com/misc/PS/XSIPS_photo.jpg


Here is one with your suggested .2 multiplier:
http://www.genecrucean.com/misc/PS/XSIPS_photo_.2.jpg


And here is .01 multiplier:
http://www.genecrucean.com/misc/PS/XSIPS_photo_.01.jpg

Yes, not perfect either (not going for good looking)... but look at the contrast and overall lighting range in this one. You see shadows, sky, highlights etc. Much much easier to get correct from this point.

Ok I understand that you can tweak the lens shader for different looks but even in this scene's simplicity... I think you can tell my point. Also, I want to point out because it's relevant to the point behind the thread. To even use the mia_exposure_photographic lens shader... you have to tweak the settings really really far from the defaults. Why is that? Interesting huh? In Maya the Cm2 factor at 100 is equal to XSI's 1000.

If the physical sun's multiplier is set to .01, you can use these lens shaders and get good results. It's imo impossible when set to 1 or .2

Not to mention that the photographic lens shader doesn't even come with XSI.

Having said all this... this is getting a bit OT and this specific example probably wasn't the best choice for the topic at hand. Hopefully everyone understands my point.


-g

[GeneCrucean]

Sorry I forgot to attach a quick render of the same scene with NO tone mapping and the multiplier set to .01 for reference.

http://www.genecrucean.com/misc/PS/XSIPS.jpg

[wurp]

i see your point yes, however i can get pretty much exactly the same result in xsi as the first picture in maya simply by first setting the intensity of the light to 0.1 and then adding the mia_Photographic_Exposure shader. Also, the difference in color you're seing in the sky are due to the fact that you're not gammacorrecting your render (gamma should be set to 2.2)

Im not sure why you are seing different results with the same settings, it could be that you have a different version of the shader (unlikely) or that there is something else in the scene that effects the render (more likely) but either way, mental ray is mental ray and you will get the same results if you're using the same shaders with the same settings, period.

[GeneCrucean]

Are you referring to the Cm2 factor? When Maya is set to 100 and XSI is set to 1000, you get identical results. So then what is causing this?

.xsi is attached. Talk is cheap :D

[wurp]

I don't have maya installed here so I'm afraid I can't try these settings out, the weird thing is if you look in the mi definition file the default for that parameter is 1(scalar "cm2_factor" default 1.0,), not 100 or 1000. Anyway, here is a link with some more interesting info:
http://mentalraytips.blogspot.com/search/label/photometry

I could be wrong and this parameter depends on the scale of the scene since it's per square meter, so if maya does use a different scale that might change things, I'm not sure.