Realtime Render solves funky render problem

[Speedster]

Hi all;

I have one SolidWorks model that has always refused to render out, always stopping at between 66% to 73%.  This has happened all the way back to oldShot three years ago. For some reason the CAD model (one of my first back in 2004, now upgraded to 2010) is funky or something.  Other similiar subjects, same relative size, same materials, etc. all render fine, with a 4800 x 6000 in about three hours on 8 cpu's, 16 gigs.  This model is 2.3 million polys, not really that large by KS standards.

Anyway, I gave it a try in KS Pro, 2.2.45.  Same stoppage issue.  73% at about 4 hours.

Then a small but firm voice in my head said "try Realtime Rendering".  I think I was channeling Thomas!  So I did a test at 1000 wide, set for 180 seconds.  Bingo, and it looked fine at that size.  I then set it for 4200 x 4800, my target print size, and set the time for 30 minutes, or 1800 seconds, clicked render, and headed out for a cup of coffee.

When it was finished out, it was perfectly OK for a large format print, and I could see no difference in the raw render quality with others that were fully rendered out "the old way".

So what really happens?  What's the real difference between rendering and realtime rendering?  Here's a Photoshoped image and two details of same to show the render quality.
Bill G
www.GouldStudios.com

[Admin]

Great to see that you got some very nice images with the realtime option.

The standard renderer uses more memory as time goes, and it could be that it hit a limit? Are you using the 64 bit version, which is significantly less sensitive to this issue? The realtime renderer once started will not use more memory.

-- Henrik

[Speedster]

Yes, 64 bit version.  Win7 x 64, 16 GB of ram, dual quads, or 8 cpu's.  What's odd is that other similiar projects, which I have posted before, are all about the same size (2-3.5 million polys) and same materials, HDR's, etc. all render just fine.  Overall I'm pleased with the realtimes, and I will know later today when I print some up on my Epson 4880 to actual size.
Bill G

[azonicbruce]

First off, VERY nice render. Second, how many passes are you setting the renders for using realtime? I'm finding the default 64 passes is way too "noisy". How many did you use?

[guest84672]

Use time - not frames.

[Speedster]

I used time, not frames, due to my tests showing excessive noise as was noted when above 64 frames.  I set the time for 1800 seconds (30 minutes) which seemed to do the trick.

But...  I just did another one, and a very strange thing happened, which I was going to post under materials, but it may also be a render problem in 2.2.45 so I'll post it here.

This render was 6000 wide, and set for 2700 seconds, or 45 minutes.  After pulling my beauty pass (which looked great at size!), I saved the file but left it open, with lock camera checked.  My practice in the past has been to render the beauty shot, save, then drag clay onto the model in the scene tree for the difuse pass, followed by chrome for the specular pass, both of which render very fast.  Then I close without saving.

What happened is that the clay applied to the scene (model) fine, but the render was all black.  I had disabled Real Time Render, to do it the old way.  Puzzled, I tried to apply chrome, but it would not take, even though it was noted as chrome in the material column of the scene tree.  No new material would take, period.

So I closed out and will try again later.

Any clues?
Bill G

[guest84672]

Trying to reproduce, but can't. Sounds strange.

[Speedster]

I can't reproduce it on other bips either.  It appears to be limited to this particular model, which as I mentioned, has always been funky and refused to render normally.  I closed the file (without saving so not to lose my work), then reopened it.  Dragged another clay on it, and it was fine, but still would not accept a "drag onto scene" with anything else.  Closed it again, reopened it, and it took chrome just fine.  I did render out the clay and chrome while I was at it.

But, with six other bips of different subjects all was fine.  Drag onto Scene worked just like it should.

Chalk it up to "funky stuff", and no matter- we just move on.

Bill G

[justindustrial]

This post stood out for me simply because of the context. What a contrasting idea it is to render an old Locomotive in 2011's industry-leading digital rendering software! Very cool connection between old and new, I'm sure the founding fathers of our industrial society would have appreciated some CAD software when designing the first locomotives!

[Speedster]

Thanks for the comments on context.  I do a lot of work for museums, scholars and historians in the field of Industrial Archeology.  You can see a lot of it on my website www.GouldStudios.com, and many of my models are on Turbosquid, where they have been well received, especially for period films.

It always amazes me at the exceptional craftsmanship of our forefathers.  And, most of the CAD tools we use are grounded in ancient practice, like "Revolve" (bells), "Lofts" (ships, etc.  I still have my lofting templates from 40 years ago), and "sweeps", which we used to "run" in plaster against templates.  SO much easier today, but... are we losing something in the process?  The great Industrial Designer Henry Dreyfuss (for whom I did modelmaking for in the late 1960's) said "Just because we have the tools does not mean we should use them".

Bill G