Architectural Rendering Help Needed Please

[morph106]

hey guys,



here are some design pieces that I've been working on. At the mo its just scaffolding but I've really been having a lot of problems.

One of which is that there is so much geometry so my memory gets flushed constantly.

Another is the fact that any renders done (most of the geo assigned to a miaMaterial) fail to generate clean alpha channels to use as mattes to render image in passes.

Another is the render time of rendering an object with a geo duplicate or instanced duplicate.



Here is a render of the structure:

http://img90.imageshack.us/img90/6504/multicellrender01we8.jpg


but notice how I get a weird alpha which I don't know how to use as a mask in photoshop:

http://img218.imageshack.us/img218/8071/multicellalpha01dy2.jpg



attached is a render comparison of 2 rows only when I duplicate it as geo and then as geometry:

http://img218.imageshack.us/img218/702/dualcellrowcomparison01rg8.jpg



I'm curious to know why the instanced duplicate exploded my render? Is this simply the nature of the beast? If so, I'm faced with either having a heavy scene that devours my memory whenever I try to render it because of the geometry, or having MR hang for an unpractical length of time trying to render multiple instances.

You can see hw this can become ridiculous once I duplicate the rows 40 times and then house them in a glass cladded building rendered at 2k...

http://img228.imageshack.us/img228/1457/multientry01rp1.jpg


guys, I really am stumped. I love maya, I know that this type of thing is possible but its so depressing modelling in detail only to realise that I can't render it.

specs:

xp home edition

pentium D CPU 2.66GHz

2.00 GB of RAM

Maya 8.5

single row file size 7 mb

dual row file size(geo) 30 mb

dual row file size(inst) 13 mb

[flux]

i can only help with one of your problems.. the alpha channel wierdness happend to me and i found that it was happening to me because i was using MR materials.. as soon as i changed them to a blinn or whatever the problem was solved. kind of annoying. if anyone can explain why this happens itll help us both out :)

and how many polies is the scene?

[T_Low]

Have you already activated in the Render Settings/ Mental Ray >Custom Entities >Pass Custom Alpha Channel ?? This enables Alpha-output for MR-Mats

[morph106]

T-Low, you are the man!

I tried it and it worked!
http://img59.imageshack.us/img59/4245/cellandtraverse01ib6.jpg
http://img59.imageshack.us/img59/2469/cellandtraversealpha01ho0.jpg

I'm gna mess around with a couple seperate renders to see how they comp together but how would you comp a render of a glass building with an object inside. I don't get how I'd render the glass out to be able to comp it so I could see the object inside once I've taken it into After Effects.

If anyone can point me in the right direction, I would be very grateful.

Thanks for all your help guys, mymentalray ROCKS :D

[flux]

thanks heaps T-low!!!!

the glass should be like semi alpha so when you bring it in to after effects put it on the layer above the inside objects. and you will be able to see throu the glass.

[morph106]

Thanks Flux, damn I'm glad I have access to MR Gurus. Really makes a world of difference.

Does anyone have experience using mssive scenes with MR and getting render jumps when they use instances instead of duplicate geometry?

Anyway, I'm tryng to beak the structure into groups so that Maya won't crash during rendering. Any suggestions would be great!

[bmcaff]

I think the best thing you can do in this instance is to look at reducing the density of your geometry. Given the building design I can't really see that there would be any problem rendering it since you seem to have a good machine. You could keep a few detailed sections and replace the ones further away from the camera by more low res substitues. Especially since the structure is covered by the glass.

[temiroff]

Create a new Sufarce Shader and then put on color your material and then control alpha by Out Matte Opacity

[morph106]

@bmcaff
Oh man, I actually got a post from Brendan McCaffrey himself!

Brendan, the work you do is exactly what I want to do. I have gone through your car rendering tutorial countless times (sorry to say I need to keep going through it) but your architectural renders are exactly what I want to emulate. If I could create renders like anyone, I'd want it to be like you. When I started collecting images to keep as information, your "Calle Leon y Castillo" piece was one of my favs! Sadly, my knowledge of render passes is still at an intermediate level so I have a lot to learn.

Please if you could elaborate on how you created "Calle Leon y Castillo", I would be forever in your debt. Was the entire piece rendered out in passes and than comped in photoshop like your peugot piece? I was also wondering if you rendered out those cars and then scaled in photoshop to fit in the distance...
...like I sed before, I really admire your work because your doing renders on the same level and above that of 3dsmax and vray. Something I really applaud because I know I can get the same result one day. Your a testament to that.

I'll dumb down my geometry so that Maya doesn't crash from rendering 50 pieces of geometry that are 1500 units away from the camera.

Again, please impart any knowledge you can..

@ temiroff
thanks for the tip about the surface shader. as soon as maya stops crashing, I'll try out and post my results.

-Josh

[bmcaff]

:o erm.. ok... haha.. thanks.
Well to answer you question, that image is a photomontage with the building integrated into an existing photo which I shot. I do tend to break down images like cars more than arch viz stuff cos the materials are more complex. However there are several benefits to doing additional passes for arch viz too. Glass being a major issue. With exteriors (and also interiors) I try to get a one shot beauty pass to have as a starting point in PS to do the final image. You could break it down into passes if you want but i feel for arch it is a bit overkill. I can generally get what I want in one pass. I nearly always render a dirtmap pass to fill in small details. I do mask a lot of it out so it is only applied where it should be though.

I have a standard light rig I use for generic arch viz jobs that don't require anything unusual. It is a daylight system and is pretty much the same as in my Peugeot image except even simpler. Basically it is a light dome and a sun. I still use maya 7 so have not explored and sun/sky setups but have used Vray system in max and what I do is similar. I do use the physical light and the colour temp node and on the dome I use a ray type (much mo versatile than IBL for me) and FG rays have a colour temp node applied also and a HDR for reflection rays.

With every image I always do a lot of finishing in photoshop and I have posted this video build up of one of my interior rendering. (scrub through the timeline to see the buildup a bit slower)

http://www.bmcaff.com/articles/movies/interior.mov

I will try to do an exterior breakdown in the same way soon. I hope you can see what goes on here. The initial work is usually to sort out the tone and general brightness contrast of the image. I sometimes apply a shadow highlight effect to remove any ugly blackness from the shadows. Then I duplicate the layer several times and play around with blending modes in PS to get a nice tone going. Then sometimes like in this video I add a direct light pass (no FG or GI) or a reflection pass to boost my highlights. Then the masked dirtmap/AO pass. The it is details like plants. The blooms and flares (see the article on my site for info on how I do this). The final colour grading to set the mood, usually hue/saturation or photo filters to make images warm or cool.

I hope this answers you question. If you want to clarify anything just shout out.

[lee griggs]

nice movie Brendan. The difference between the first and last images is startling. I sure would love to see the layers in photoshop. Thanks for sharing that.

What looks like the reflection pass really brings the image to life.

I wasnt sure what you meant by this though?:

I sometimes apply a shadow highlight effect to remove any ugly blackness from the shadows.

sounds intriguing :)

[bmcaff]

Shadow/highlight is an image adjustment in photoshop which operates on shadows and highlights of an image. It works like levels but with a built in selecter which you can let you to determine the tonal range that is affected as well as the spread of the selection (how the effect blends into the rest of the image) Default values are usually too high but it is a matter of taste how much or how little you use. (I did not need to use it in this case at all, but the bathroom from the same project needed it badly).

Here is an screen grab of the layering in PS. Most of my PSDs look like this but with more layers.
http://www.bmcaff.com/post/interiorlayers.jpg

Obviously getting the perfect render out of MR is the ideal but when time is an issue (when is it ever not?) then anything goes. Render time on interiors at large sizes can be very long indeed. From a production and comercial point of view there is a trade-off between speed and quality. Hopefully you make up the difference in PS.

[lee griggs]

cool, I will try out some of these post techniques the next time I do an aec render. Even though I dont have the same deadlines that you guys have, it looks like it gives a lot more control on the end result.

Thanks again Brendan :)

[MasterZap]

Does anyone have experience using mssive scenes with MR and getting render jumps when they use instances instead of duplicate geometry?

Have you tried switching to the "GRID" BSP?

mental ray performs better with instanced geometry when using the grid bsp, because it has sub-grids inside the instances, meaning, one grid is re-used for every instance, whereas the traditional BSP is global, so it gets duplicated for every instance.

/Z

[morph106]

Thanks for the tip Master Zap. I thought the general rule was to stick to either BSP or Large BSP only but sure enough, my instance test render resulted in the Grid method being the faster of the three as you can see:
http://img141.imageshack.us/img141/8513/columncomparison01zq5.jpg

I noticed however that I lost a little shadow information in certain places and am unsure as to why. EDIT: Though I didn't have any direct shadows in this scene. Only fg.

I'm also aware that removing geo that isn't in plain site would go a long way to easing the burden but I'm mindful that a lot of Arch Vis rendering that comes from AutoCAD for example, includes every piece of geometry when rendered for animation with MR. Could anyone correct me on this. I've just seen so many arch viz movies where it appears they had to render every detail for fly thrus and the like.

[morph106]

hey yall,

well I've lost a couple nights tryin' to brainstorm how I can get my rendertimes down while retaining all geometry in my scene. To date I've tried to render a 10 row column of geometry and instances, both times resulting in Maya just freezing. I'll post the instance file for anyone willing to give me the smackdown for yet another obscure MR setting...hopefully I'll be growled for using instances or geometry and someone can explain what I was doing wrong..

http://www.badongo.com/file/2546529

I hope you guys can impart but a little of your knowledge to me one last time.

its too late to stare at Maya tonight so I'll try again tomorrow

[iddidy]

Hi morph106,

Just a quick question on your scene setup with the white environment. Can cou post a simple scene or tell me how you achieve this look? When I try to get a product sittling on a white floor with a shaddow and in a white environment it never looks right. everything is blown out!

Thanks

[morph106]

Hi iddidy,

If you check out my posted scene file, you'll notice that it is just a white bg and a plane with use background shader assigned to it. then its largely the default fg settings lighting the scene. I've also added a directional light if you notice any direct shadowing in some of the renders.