introduction and some questions

[texturama]

hi to everyone! i thought i'd introduce myself and shoot some questions rightaway..

 

i am a third year interior design student who experienced with autocad and rhinoceros (both in 2d and 3d) for some time now. eventually last summer i decided to learn maya (main reason being my interest in character design) and did that through tutorial videos and through experiencing (with school projects going on and some free time work). of course still have a lot to learn, still continuing. and got a load of questions...

 

since i loaded maya i had a problem while importing iges format files into it. i know geometry gets lost through this operation or just gets messy. so what i did was to decrease geometry, for instance in one of my projects i did that by creating one closed polyline for inner wall line and another closed one for outer wall line. then i imported them to maya though i had to group and rotate them in order to get them flat on the ground. and eventhough i changed my grid size the lines stood too big. so i had to scale it. my question is is there any other way which is more accurate then this one? would it be better to open it in some image format and placing it as an image plane? (which i tried and ended up with a very glitchy weird look. is it me?)

 

for rendering i first experienced with maya software and got my head around the workflow then i wanted to take my renders into mental ray to get more realistic results. i know mental ray is able to render maya nodes but is there a reason why i should choose them over mental ray nodes while rendering in mental ray?

 

also i still do not understand how mental ray lights differ from maya lights. do i have to connect those nodes somewhere somehow because they have fewer attributes? and how do i use physical light node?

 

 

i guess that's it for now. i'd be very grateful if you could help me clear my mind a bit.

 

thanks in advance and hi!

[Karlfucious]

Welcome.

 

First off the reason why you have to group and rotate is because by default Maya's up axis is in the Y direction where as in most other software its Z. You can change your up axis in the preferences.

 

Mental Ray Materials are better because they are more accurate. Also in most cases they render faster than the Maya equivalent because they do not have as many attributes to calculate. For arch vis work you should primarily use the MIA material. It has neat little features and a lot of presets that make your life easier.

 

Mental Ray Lights are also more accurate. With Mental ray lights you still have to use regular maya lights but you have to connect a mental ray node to the light shader.

[HamburgerTrain]

There's a nice little rule you can use to get physical photometric lights in Maya using IES profiles.

 

It's some work to do though.

 

- First you have to use Sun + Sky with the mia_photographic lens shader (read up on the Maya docs how to set this up).

- When that is set up and you have point lights distributed throughout your scene, attach a mib_light_photometric to the color slot of your lights

- Attach a mib_cie_d node to the mib_light_photometric's color slot.

- Set it to an intensity of 3180 on the mib_cie_d node and adjust the temperature to whatever you want

- In the mib_light_photometric node, create a Light Profile and load in your IES file.

- Once you have selected your IES light, you need to know it's intensity, so using a program called IESviewer, find out the cd value of the IES light

(You have to make sure the Show Orthogonal Diagram in the program is turned on as well as Fit Goniogram). Once you get the cd value, enter this exact value into the profile light's intensity and change falloff to Quadratic

- If you did all these steps and render you should get an accurate result but you will have to change the Star/Stop attributes of the mib_light_photometric node until it renders properly

- Of course, make sure your scene is modelled in real world units (ALWAYS leave Maya's units at CM's no matter what!!!!!! ALWAYS!!!) It's a pain but many things do not work like curve intersections when you change the measurement units...funny bug!

 

I'm happy to help if you don't understand any of that.

 

It sounds like a lot of work and it is compared to other packages...but this is mental ray we are talking about. Vray for Maya is a hundred times easier!

[texturama]

i think my main problem is i dont know my way around the connection editor. i dont know how to connect mental ray lights and materials to other stuff. and i dont seem to understand how those connections work and how some does not without connections. i want to know what those nodes do exactly and how they work within each other. so if there is some sort of tutorial link or something you could post feel free because i always end up with somehow irrelevant tutors and they make me more confused then before.

 

for instance consider a rectangular shaped light fixture on the ceiling. how do i make it look like its illuminated and make it emit light the correct way? is it the point where i would be needing ies lights?

[Karlfucious]

Connecting mental ray lights is pretty easy. In the lights attributes there is a slot called light shader. In that slot is where you connect the mental ray light in most cases. There are a few exceptions as Hamburger Train mentioned about the mib_cie_d and such. Also If you are using GI you need to attach photonic lights to the Photon shader slots as well.

 

Here are a few useful links that should help you out a lot.

 

Here is a great set of tutorials for interiors

www.floze.org/2008/07/six-tuts-on-light-and-shade-part-i.html

 

video tutorials, shaders, exc.

www.mymentalray.com

 

CGTalk which is probably the most active maya forum that I have found anywhere. Also full of great imformation from professionals.

http://forums.cgsociety.org/forumdisplay.php?f=87

 

Digital Tutors. A great site with tons of DVD training. Also Quite a few free videos as well.

http://www.digitaltutors.com/digital_tutors/index.php

 

Gnomon. Great DVD training. Not Free but well worth it.

http://www.thegnomonworkshop.com/

 

I hope those help out a little.

[texturama]

sorry about the delay, been busy with school.

 

karlfucious, i checked a couple of floze's light tutorial and they have been very heplful eventhough i could not finish them all. i'll go back to them when i have more time.

 

but there is a part i did not understand, in the part about gamma correction it says:

"If we use “value” textures however (like for bump maps, displacement maps, or anywhere where a texture rather feeds a value than an actual color), we'd have to disable this mechanism for the particular “value” texture by switching a gammaCorrect node in front of it, with the desired gamma compensation (2.2 in our case) filled into the gammaCorrect's Gamma attribute "

 

how do i do that?

 

also when i'm using GI, is it "mib_light_photometric1" that i have to connect to photon emitter slot?