How to create a saved GI map using irradiance/lightcache configuration in Mental Ray

[R.Stewart]

How to create a saved GI map using irradiance/lightcache configuration in Mental Ray

 

Hello,

 

I'm working through the 3DATS 2009 book and progress has come to a grinding halt. I'm in the compositing section which is done using vray along with fusion for the post work. It states b4 the exercise that it can be done with mental ray and any other after effects program. I have Adobe After Effects so I'll be using that.

 

The first step is creating a saved GI map and there is a step by step process in the appendix on how to set this up but it is for Vray. The first move is to set the primary and secondary bounces to light cache, step two is In the global switches rollout enable the don't render final image option. So there is 23 steps here and I don't know where to start. I went to the Indirect Illumination rollout, I know you can make photon maps there but I don't think that's what i'm after as there are very few options available there. I've searched the internet but can only find Vray help.

 

If you can give me any insight into where I can start with this that would be awesome. I'm using Max Design 2012, Mental Ray.

 

Thank you,

[Dave Buckley]

Irradiance map and light cache are vray gi methods, in mental ray you have final gather and global illumination. Each of which have there own options to save out the calcs as separate maps as described. There is no don't render final image option in mental ray but you can just generate an fg map or gi map without rendering the final image

[R.Stewart]

Hey nice one Dave,

 

So I just go to the -

Reuse (FG & GI Disk Caching)

Under mode change the drop down to - Single file only (best for walkthroughs and stills)

Should I check - Calculate FG/GI skip final rendering?

Then in the Final Gather Map section drop down - Incrementally add FG points to map files

Then choose where to save it

Then generate the map

 

That should be it for the FG?

 

Then for the GI just select - Read/write photons to map files

 

So basically the point of this is to have a separate file to mess with in Adobe After Effects right? So it won't effect the rest of the scene. Or the other way round? I gotta read over it again

 

Thanks for the help Dave

[R.Stewart]

Also it's a outdoor scene. A bridge going over water so I shouldn't even use GI hey? Just the FG map. So I made the map. I thought it was going to go through the animation but the camera didn't seem to move i guess it does it in it's head.

 

I got these warnings too. Anything I should worry about there? the materials and the shadows are a bit of a concern.

 

SYSTEM: Production renderer is changed to mental ray Renderer. Previous messages are cleared.

MSG 0.0 error: Texture map "Map #135979680 ( Missing TextureMap )" is not supported by mental ray and will not render.

MSG 0.0 error: Material "Material #30 ( Missing Material )" not supported by the translator. Will render black.

MSG 0.0 error: Shadow generator "Missing Shadow Type" on light "road lamp 02" is unsupported (mental ray only supports raytraced and shadow maps). Using raytraced shadows.

MSG 0.0 error: Shadow generator "Missing Shadow Type" on light "car_headlight_01" is unsupported (mental ray only supports raytraced and shadow maps). Using raytraced shadows.

 

 

Thanks again

[R.Stewart]

It just get's to be more and more of a nightmare with each step. I think I'll just try and install a free version of Vray. Tomorrow.

[Justin Hunt]

You will have to convert all Vray materials to Ach&Design and all shadow types from Vray shadow to Raytrace shadow.

 

Simply changing the renderer from Vray to mentalray is not enough.

 

Not sure whats going on with the camera though.

 

jhv

[R.Stewart]

You will have to convert all Vray materials to Ach&Design and all shadow types from Vray shadow to Raytrace shadow.

jhv

 

Thanks Justin do you know an easy way to do this. I tried using a script I found but I think it's a bit old, I did this http://mentalraytips.blogspot.com/2007/02/max-9-converting-other-materials-to.html

 

But still got this...

MSG 0.0 error: Material "Material #25 ( Missing Material )" not supported by the translator. Will render black.

 

I do really want to get this done in mental ray, because it's my ray. We'll be using it for animation next semester so I have to get this happening. The book was so easy to follow till now! I think I need to learn a lot more about animation and Adobe after effects before trying to take this on. Even thought this is supposed to be a starting point. ha. Also I'm missing the last few support files for the tutorials and they can't be found anywhere. I've messaged Brian Smith the author to try and get some assistance with no luck.

 

I'd still like to know about material conversion though if you'd like to share.

 

Thanks again,

 

Richard

[Justin Hunt]

I used to use that script to some success, although nower days I prefer to do it manualy as the script isn't a 1 for 1 conversion.

 

Generally I load the material into the editor, make a copy of it, change the original material to and A&D and copy and past the maps from the vray version into the A&D version. Its tediouse but doesn't take too long.

 

Be sure to have "Incompatable" ticked in the Material/Map Brouser, otherwise you wont see any of the vray materials/shaders

 

jhv

[R.Stewart]

hey a small victory : )

 

got all the Vray materials to show but they are just a boring matt grey so no bitmaps to copy. At least I know how to do it now.

 

Good man thank you

[Justin Hunt]

too easy.

 

When gernerating the photon and FG maps, generate the Photon map first then the FG map.

 

jhv

[Dan Norfolk]

Or you can just use FG and no GI, makes your life a lot easier.

[Dave Buckley]

Or you can just use FG and no GI, makes your life a lot easier.

 

But doesn't always give you the desired results.

[carlotristan3d]

But doesn't always give you the desired results.

 

I learned mental ray thru jaime cardoso's book 'realistic architectural visualization with 3dmax and mental ray', he's only using FG and no GI. So i've been doing the same too, and quite saisfied with the result. So there's merit to what the previous poser said. I queried jaime on this and let me quote his reply: "Numerous productions companies have stopped using Global illumination parameters years ago!

 

Final gather solution alone can now produce better and faster results than the global illumination alone or/and combined with FG.

For most mental ray veterans, the Global illumination parameters are there merely for legacy reasons.

When mental ray was first introduced to Max, it was utterly imperative to use both methods (i.e. FG and GI) as the solutions were not as accurate.

Global illumination parameters take too long to compute, and the final results are often less plausible than FG alone or combined.

 

Final gather settings and its accuracy had been improved so much over the years, that it has become difficult to see the purpose of the GI parameters.

 

You can test the above theory without having to follow what other users are doing".

Although I'm more of a sketchup+vray user now, whenever I get back to MR I only use FG. If you're just starting with MR, I'd suggest you use FG only. If you're not satisfied with the result, then go back with GI+FG.

[Justin Hunt]

Whist what jaimie is saying is true in that FG only is easier to set up initially, to get a really detailed FG only lighting solution, it can take ages to render.

 

Jaimie is also taking about the "old school" Photon/FG set-up. Where one uses fewer photons, a large radius and more samples. This is very slow to compute and render.

 

However by using more photons, a small radius and very few samples, one can get a very detailed and accurate solution that calculates and renders quickly. jhv

[R.Stewart]

I learned mental ray thru jaime cardoso's book 'realistic architectural visualization with 3dmax and mental ray', he's only using FG and no GI. So i've been doing the same too, and quite saisfied with the result.

 

Nice I've got that book here but I'm waiting until I finish the last 3DATS book which I'm on now. Good to hear you're getting good results from the lessons learned, I can't wait to get into it.

 

 

"However by using more photons, a small radius and very few samples, one can get a very detailed and accurate solution that calculates and renders quickly" Very good advice thank you Justin I remember doing a tutorial that used this technique and it looked great.

 

Cheers guys.