What helps with rendering---RAM or Processor speed.

[hdjohnson]

I have the following computer setup:

Dell Precision WorkStation 450
Processor: Intel(R) Xeon(TM) CPU 2.80GHz Clock Speed 2.8GHz
Memory
Memory Slot 1 Description [DIMM_A]: 512Mb
Memory Slot 2 Description [DIMM_B]: 512Mb

Display Adapters ATI FireGL X1 AGP Pro 128Mb
ATI FireGL X1 AGP Pro Secondary 128Mb

I'm having tons of problems rendering and doing walkthroughs.
I'm trying to do a rendering at 9900 x 7500 (which technical support said Revit can handle) and my computer runs out of memory.


When I try to do a rendering, my system will only do about 30 frames on a walkthrough before running out of memory.

My question is: Would it be better to get a faster CPU or should I keep the same system and upgrade to 2 gigs of RAM?

Any advice or suggestions would be greatly appreciated.

[hand471037]

Well, the processor speed is how fast the render job will go, whereas the RAM will be how big of a job your computer can handle. In your case a faster processor isn't going to do anything for you, it's the lack of RAM on your computer and your extremely high DPI demands that are choking your computer.

You can try going to 2 gigs of RAM and see if it helps, I know my old machine that had 2 gigs never choked on any rendering job. However, you might want to revisit your DPI demands. They seem *very* unrealistic IMHO. Why do you need such high DPI? Are these images & walkthroughs going to be on a Sony Jumbotron? :)

Remember that every time you double the DPI of an rendered image, your quadrupiling the file size, and therefore the amount of computer effort to generate that image. With Rendering you always want to make the image the *minimum* size you can get away with, otherwise it's going to take way to long to be practical.

The only other thing I can think of, if you really need your images to be so large, is to not use Revit to render them. Revit's rendering engine is not up to such high demands, and there are a lot of things available for MAX/Maya (including stand-alone render servers & 'bucket' rendering) that would make generating such huge images much more efficent.

[Scott D Davis]

Someone correct me if I'm wrong, but isn't it true that a 9900x7500 image will contain 74250000 bytes of information? Thats 74 megs for ONE image! If you are trying to render a walkthough at this resolution, at 30 frames per second, one second of uncompressed video would be 2.2 Gigs of information.

I think this is why your renderings are choking. When Revit supprt said it could handle 9900x7500, I believe they meant one image, not video!

I would try rendering one frame of what you are trying to do, and see how big it is, then do some calcs on your own. What you are trying to do would be best handled by Pixar!

[Archman]

I agree with Scott. 9900 x 7500 is huge. I don't think even the highest quality HD TV's can display resolutions that high.

In fact, I do renderings at 3300 x 2550, and they print remarkably crisp even at large scales.

I can get away with even less resolution for video.

What are you trying to achieve with such high resolution?

[hdjohnson]

Sorry, I think I should have clarified the information better....

The walkthrough and the still image are of the same project but different sizes. Here is the correction:

The still image we need to plot at 40" x 30". I was using the 9900 x 7500 so that this would give my a high print quality. The plotter is a HP 5500 color plotter. So do you think I could render at a lower resolution and still get the same quality?

The walkthrough is going to be displayed on a TV. I was hoping to make the rendering broadcast quality. These are the settings I'm using: Pixel dimensions are 720x432 (I'm following the 10" x 6" crop region according to Cyril's book). My Rendering settings are set to Good for Raytracing. What settings do you typically use?

Thank you for your earlier responses. I really do appreciate all the help...

[hand471037]

Currently, your big rendering is at 250 DPI. That's a nice resolution. You might be able to go as low as 100-150 before you would notice a big difference in quality IMHO. Keep in mind that most glossy magizines are around 150 DPI, and that newspapers & billboards are somewhere around 32! Also going from 250 DPI to 125 DPI would make the file size 1/4 as big, and it would take 1/4 the time to render. Pick your final DPI wisely!

Depends on how far away the people viewing this large image will be. :)

Also another thing to keep in mind is that rendering an image at a very large DPI is going to take a very long time, for you're also increasing the level of detail and number of light paths the raytracer has to think about. But if you need an image that's really 250 DPI and that big you might try to first render the image at whatever your computer will support, size-wise, like at 150 DPI- and then increase the size in Photoshop to the final image size. When you increase an image's size in Photoshop, Photoshop will try it's best to 'fill in the bits' so that it still looks decent. I've been able to almost double image sizes in photoshop and keep the same level of visual quality.

Another thing to keep in mind is that while your printer is a 600 DPI printer, that doesn't mean that you want to print at 600 DPI; it just means that the printer will render things like color and shading much much better than a lesser printer. Try this: take a 200 DPI image, and send it to your color printer using the printer's best quality settings; then send the same image again but this time with the printer settings at a much lower DPI/quality. You'll see that the image is just as 'sharp' but now the shades and colors will look crappyer.

[GuyR]

The walkthrough is going to be displayed on a TV. I was hoping to make the rendering broadcast quality. These are the settings I'm using: Pixel dimensions are 720x432

Isn't NTSC 720x480? Why 432? Anyway I can render about 30sec of DVD-PAL (720x576/25fps) walkthrough on a 3Ghz/1GB ram laptop overnight. I rely on sunlight only, so day scenes only in this timeframe. Turning on lights slows things down considerably. If I want lights I run the rendering over the weekend.

Don't render pauses /still frames in revit. You can add these wiith a decent video editor when you add the titles, transitions etc. You can also do nice B/W movies by rendering in colour and using a B/W video filter when creating the MPEG2's. Much quicker than changing materials in revit.

Guy

[hdjohnson]

Thanks to both of you for your responses.

jeffrey mcgrew, I'll give 200 dpi a shot after I finish my walkthrough...

Guy, would you mind telling me what you render settings are?

Thank you in advance.

[GuyR]

Guy, would you mind telling me what you render settings are?

Here's a screen dump. I use a plain background and I'm not trying to achieve a photo realistic image. On TV it's just not worth trying.

Guy