First Mental Ray Render

[iaga]

Hi People,

 

Here's my first Mental Ray render from Max Design 2009. I've been using V-Ray for a year and a half and now for efficiency reasons at work (we've started using Revit Architecture Suite), I've had to export FBX models from Revit and bring it into max to render some decent shots.

 

I'm such a beginner in Mental Ray, as you can tell from the rendered image, therefore, all help is most welcome.

 

I'm using Mr Daylight system with Mr Sun, Sky and atmosphere. BTW the sky went missing as i accidently saved it as a PNG file after a 2 and a half hour render. Any help with any aspect of the image to improve etc is most welcome and I look forward to it...

 

Thanks

[ABK]

Hi,

 

Looking at the image, my approach would be to take each element at a time. Get each one right and then look at the whole image.

 

To light the scene I often use the 'material overide' option in the 'processing' tab of the render toolbar. You can create a standard material with ambient occlusion and drag this into the material override material slot. This will then render your scene as with ambient occlusion. It allows you to get quick renders to get the highlight, shadow balance correct. You can also check the softness of your shadows easily. After this is correct turn material override off and focus on other areas. (Also turn down your indirect illumination settings for test renders and use low anti-aliasing. this will speed things up).

 

I'd check your brick is the right scale. it looks a bit small to me. When it's the right scale apply a bumpmap and ambient occlusion. try some close up renders of the bricks and tweak your values until it's looking good. Maybe also think about using a reflectivity map (arch&design materials) and put the glossiness down to about ~0.3. This will give you the specular you see on brick wall and add the variation you need.

 

For the glass, render small window sections and check your reflections are looking right. (at the moment you don't seem to have much reflection). I usually use a standard material for the windows but also mainly do interior stuff so not sure what's best for architectural glass...

Further to that, if you make the windows transparent and add a basic interior (with lights) you'll see a world of difference.

 

For the entrance (round section on right hand side) I'm not sure what the material is meant to be. Let me know and I'll try my best to send you an appropriate material.

 

Other things:

1. while working on the render I'd ignore any montaging - get the render good and then work on the post.

2. I'd get a better grass texture. The one at the moment repeats a lot. This throws the whole image.

3. Use ambient occlusion! It really makes a difference. I often do a seperate ambient occlusion pass for my renders (material override - ambient occlusion) and then comp it over the standard render in photoshop. This gives you more control over your ambient occlusion settings.

 

Hope this helps.

[iaga]

Hi Antony.... Many thanks for such a brilliantly detailed reply. I'm currently working on the AO passes and material overrides to correct the lighting and shadows.

 

In regards to your query about the material on the round area on the left - It's supposed to be copper/ zinc cladding.

 

Once again many thanks... I'll post some more shots up once i've worked on your tips.

[iaga]

Received email Antony - Many Thanks... Exactly what I was looking for

 

Still working on the render - One problem I've realised is that no matter however much i try to increase the sun/ sky lights the shadows are really, really dark - any idea's ... anyone?

 

Thanks.

[ABK]

Try upping the number of diffuse bounces in the 'indirect illumination' tab on the render menu. will increase render time though.

 

In the past i have cheated by putting four shadowless target spots in the scene, each pointing towards the centre at 90 degrees to each other. I give them a low low value (0.05 to 0.15). This isn't good practice but it has worked for me to help fill the dark areas with light.

[Stan Zaslavsky]

my 2c worth will be to be careful with 2d photoshop elements and their shadows - it seems your tree shadows are going in the other direction vs people's shadows

 

keep going

[Justin Hunt]

Exposure control is your best friend with regards to controling the darkness of the shadows.

 

Please post your render settings, especially the FG (and Photons if your using them) because this should render in under 10 minutes

 

jhv

[iaga]

Thanks for your help guy's... I'm testing all your tips right now...

 

Here's my render settings:

[Justin Hunt]

OK

 

FG density of 1.5 is too much, often there is no need to go over 0.8

Diffuse bounces could go up to 2 although if you need to go above 3 its time to use Photons.

 

What res are you rendering to?

 

jhv

[iaga]

Cheers Justin,

 

Was rendering to 2400x1800 res

[iaga]

This is my latest rendering and working with MR is really frustrating me... I'm trying to correct the scene lightings but every time i switch the materials back on from the override the grass always seems so saturated, it's so annoying... pls help someone...

[iaga]

BTW I use RPC content as this is all we have subscription to at work.

[iaga]

Here's my daylight and environment settings:

[Justin Hunt]

For the grass, you can drop the Diffuse level (of cause you are using A&D shaders right?) to 0.8. it will darken but the colour bleed will be less

 

Exposure control, use mrPhotographic instead. and adjust the EV values to suit

 

Sun and Sky

 

Leave them both a multiply 1, increasing these is adding alot to the grass colour bleed issues and increaseing rendertimes. Use expose control to brighten the scene instead.

 

Just to be sure, are all the materails A&D or Pro materials? and all objects been assigned a material?

 

jhv

[iaga]

Thanks Justin... starting to make those amendments already and starting to notice the difference.

 

As the model is an import from Revit, the materials are all pro materials and now I'm using A&D materials on some so its a bit of a mix.

[iaga]

Guys... A quick question ...(well the question's quick, dont know how long it'll take to do:D).

 

I'm trying to do a clean white render with high amount of reflection from the sky... the problem is what I've been trying so far has given me really grainy images, and the reflections look really flat which I cant seem to sort it out.

[SandmanNinja]

That almost looks like an AO render pass.

Try upping the samples on the white material.

What AA settings are you using for this particular render?

[iaga]

Sandman... Here's my AA settings:

 

Thanks.

[SandmanNinja]

Those settings should give you good renders.

So what are your number of samples on your material?

[iaga]

i've just up'd the samples and the renders aint too bad now ... AO in diffue = 30 and AO in special effects = 16.

 

The only prob now is that the windows look too flat... how can I improve this please.

 

Thanks for all that have helped BTW.

[hockley91]

How did the final image turn out? The shadows were looking much better as well as the lighting on that last image.