Rendering and the "optimize on" option - learning the hard way

[Barton Brown]

What follows is the sad tale of wasted time due to a faulty "problem debugging" decision followed with a recommendation for others that may experience similar failures with rendered views.

the problem:
For quite some time (back in CA 9.5 days until now with CA 10.05) I have experienced rendering failures on one particular plan. The failure mode has always been the same, even when using two different computers, and would appear as a basically blue screen with some slight representations of the desired scene showing as faint, ghosty white images. But, depending upon the scene to be rendered the failures may or may not occur (indoors usually worked, outdoors usually failed).

my faulty debug decision:
Last weekend I had finally had enough with not being able to consistently render scenes on this plan. I assumed that since I was getting similar failures on more than one PC AND since this plan had been migrated forward from CA 8, that somehow it must have gotten some subtle corruption and that I could fix it by redrawing the plan.

So, 10-12 hours later the plan was pretty much back to the level of detail of the original plan, and what I noticed was that as more detail was added I started to get the same old failures - dang!

Solution/recommendation:
Tonight I decided to RTFM a little regarding rendering options (actually, I didn't RTFM until I had changed a number of different rending options in the "preferences dbx" and found one that fixed my problem ). Guess what? Even though my video card has 512 MB of RAM on board, it wasn't enough for the level of detail the plan contained for outdoor scenes. By unchecking the "optimizations on" option, my problems went away.

Here is what the help screen says about this option:

"The Use Optimizations option directs your computer to save rendering data to memory. On some OpenGL graphics cards, this may cause problems if the rendering data for your model is greater than the amount of memory on the card. If your computer stops responding when rendering, try clearing this check box. This slows down the rendering time considerably, however: if the problem is not solved, leave the check box selected."

I had read this a while back but somehow my blue/ghosty screen and "computer stops responding" didn't equate in my brain.

On a positive note, with my new computer with a fast PCI-express nVidia 7800 GTX video card, I can't really tell any difference in the rendering times (and I'm not going to measure it either )

Anyway, if you are having strange rendering issues, don't be afraid to change the options and as a last resort RTFM

Barton

[mcqueenhomes]

Thanks for that little piece of knowledge. That may come in useful someday.

It's like where I used to work, knowing that kind of thing eventually made one the guy they called to get the thing running, even though the solution may have been seemingly ridiculous.

[dstig1]

The maintenance guy with 40yrs experience retired one day. They gave him a big celebration as he was always the guy who could fix anything in the plant that stumped others.

Several months later one of the major lines broke down and none of the maintenance guys on staff could fix it. So they decided to call the retired guy back to see if he could fix it. They agreed to pay him whatever he wanted to come back in to fix it.

He agreed and arrived with his small tool box. He listened to the machine for a couple minutes, turned a couple of knobs, grumbled a bit and dug into his bag. He grabbed a small hammer and started climbing up into the equipment. The other folks followed him to see what he was doing. He arrived at a valve, took the hammer and gave it a whack. Suddenly the machine started working correctly. Everyone was happy.

A few days later his invoice arrived: $1000. The plant manager was outraged and demanded an itemized bill. So he submitted the following bill:

1. Hitting valve $1.00
2. Knowing which valve to hit $999.00
Total $1000.

They paid it...

(optimizations off )

-Dave