topic Re: 'Banded' Photo Rendering in Installation & update

'Banded' Photo Rendering

Scott Bulmer — Fri, 22 Jul 2005 01:07:15 GMT

I am at a loss for what causes (the attached) incomplete photo rendering made up of partial image bands, and am open to any suggestions. The PLN file is approximately 11 MB with the buildings as multi-story modules (5 stories total). The roof utilizes the Italian tile roof surfacer, however that layer is off for these renderings. The Open GL engine works as expected, but Lightworks does not fully render the image (even with low level settings). Light Sources is set to lamps (sun and sky objects that are turned on in the plan window), with shadow casting by lamp settings. Other smaller PLN project files photo render as expected.

Re: 'Banded' Photo Rendering

Scott Bulmer — Fri, 22 Jul 2005 01:14:30 GMT

The Open GL shaded image used prior to photo rendering.

Re: 'Banded' Photo Rendering

__archiben — Fri, 22 Jul 2005 07:22:06 GMT

each band looks to be stepping up in size and distance from the previous one by some kind of mathematical relationship . . . soooo:

in your photorendering/lightworks settings: are you by any chance using some kind of fancy 'foreground' rendering?

~/archiben

Re: 'Banded' Photo Rendering

Scott Bulmer — Fri, 22 Jul 2005 13:33:15 GMT

Excellent observation, but both fore and background are set to 'None'.

Re: 'Banded' Photo Rendering

Karl Ottenstein — Fri, 22 Jul 2005 17:29:50 GMT

Actually, the bands look like the results of one of your two processors. LW supports 2 processors, and you typically see two bands rendering at once, then leapfrogging.

I see you have dual Xeons, supporting this hunch.

So, the question is, why is there no visible output from the work of your second processor (if I'm correct)?

If what you have shown us is a screenshot, then I believe there is a problem with your graphics driver. If it is a saved file, then I have no clue at all! (After you see this banded result, SAVE the image via the File menu - then open the resulting JPG to view it: is it OK? No bands?)

Karl

Re: 'Banded' Photo Rendering

Scott Bulmer — Fri, 22 Jul 2005 17:50:50 GMT

Thanks Karl,
Both the original and this new attachment are from saved files. The differnence, today's image used a smaller size but same resolution. You can see the banding differs. Are you thinking that there may be a problem with one of the processors? If so, do you know how I would check for that?

Re: 'Banded' Photo Rendering

Scott Bulmer — Fri, 22 Jul 2005 18:07:46 GMT

Attached are portions of the model (3 building site) selected by marquee. Each building alone seems to photo render fine, and will render the roof surfacer as well if that layer is on. However, when attempting to render the entire site, banding occurs every time with surfacer layer off, and program becomes non-responsive/crash with surfacer layer on.

Re: 'Banded' Photo Rendering

Scott Bulmer — Fri, 22 Jul 2005 18:08:38 GMT

Part 2.

Re: 'Banded' Photo Rendering

Karl Ottenstein — Fri, 22 Jul 2005 18:26:39 GMT

Scott wrote:
Thanks Karl,
Both the original and this new attachment are from saved files. The differnence, today's image used a smaller size but same resolution. You can see the banding differs. Are you thinking that there may be a problem with one of the processors? If so, do you know how I would check for that?

Ah, the plot thickens! 😉

Well, the new results also suggest something involving the two processors, but the change could as easily be just due to the changed image size. Your subsequent comments, though, suggest that there could be a problem with LightWorks itself coping with the large number of polygons in the roof-as-surfaced.

Another diagnositic question: when you render, do you see more than one band making progress at once? If so, then both processors are doing their thing and the problem may be polygon count and Lightworks. If only one band progresses, then something processor-related could be amiss - but I can't see why. Works fine for me on my HT machine with 2 'virtual' processors.

I wonder if your BIOS has a setting that allows you to disable one of your processors, just like those of us with p4 HT machines have a setting to disable hyperthreading? If so, try disabling one and repeat. Or, since it sounds like you have multiple computers - take the model to one of your other computers that has one processor and see what happens there.

That will eliminate the computer from the equation, bring us back to Lightworks.

Interesting problem.

Karl

Re: 'Banded' Photo Rendering

Scott Bulmer — Fri, 22 Jul 2005 19:14:05 GMT

Karl,
The polygon congestion starts when trying to render the entire 3 building site with the roof surfacer layer on in Open GL shaded mode, and/or wire frame (it never gets to the Lightworks stage). When marqueed, each building alone renders fine in both Open GL shaded and Lightworks with the roof surfacer layer on. See attached.

Karl wrote: when you render, do you see more than one band making progress at once.

For the entire site without roof surfacer, Lightworks renders the image starting at the top, then skips with a blank band, then repeats band/no band down the image. For the entire site with roof surfacer, the program becomes non-responsive at the Open GL stage. For marqueed portions of the site one building at a time, Open GL & Lightworks render as expected (see attached).

I will try to test render on another workstation in addition to having a tech remove one of the processors and test as you suggested. This may not happen today unfortunately.
One other thing, I monitored the Task Manager Performance tab durnig the rendering process where it showed both CPU's having activity.
Thank you so much for your insights.
Scott

Re: 'Banded' Photo Rendering

Karl Ottenstein — Sat, 23 Jul 2005 19:21:47 GMT

Interesting, Scott. There's lots of polygons in them there tiles! (Nice looking model, by the way.)

So, if it never fully displays in OpenGL or wireframe, it does sound like polygon overload. I'll be interested to hear what happens on another computer.

Not being able to view the model in 3D blocks all kinds of other options. For example, Artlantis R deals with large polygon count models very well, by all accounts. While you could download the demo version (30 day trial) to check it out ... you have to export to ATL from the 3D window ... and you can't display in the 3D window...

That you observe what you do (banding) when the roof surfacer layer is turned off makes this more puzzling. I would have thought the all of the tiles were the problem. So, there may be more than one issue going on. Look forward to hearing what happens on a different computer.

(Re: your earlier message, I don't think you have to have a tech remove a processor - not worth the risks of physical removal. If there is not a BIOS setting to logically disable one processor, just continue your tests on a different computer.)

Karl

PS One last idea. I had a problem with a 128 MB graphics card once when I stretched my 3D window to span multiple monitors, or even placed it on my secondary monitor. Have you gotten the same results (not able to display in OpenGL) if you place the 3D window on the primary monitor only, and reduced in size to be maybe 800 x 600 pixels worth of whatever your total screen space is?

Re: 'Banded' Photo Rendering

Scott Bulmer — Mon, 25 Jul 2005 15:26:58 GMT

Karl,
Thanks, alot of blood, sweat & tears have gone into that project (no growth California policies).

On a Pent 4 – 253GHz – 1MB ram, Lightworks engine rendered the image with roof surfacer layer off as expected without banding. So that isolates the Dual Xeon having some issue.

On the Pent 4 with roof surfacer on, Shaded Open GL engine rendered the image (no crash as on Dual) in a little more that 3 hours. THEN commenced the LW Photo Rendering process, waited 4 hours finally going to bed. The image was unable to render with the attached error message. You are correct; there must be too many roof tile polygons in the 3-building model.

There appears to be some exponential relationship of rendering time with roof tile surface area; each building alone will render with Open GL in approx. 5 minutes, then an additional 5 minutes in Lightworks (one would estimate 30 minutes total if 3 equal buildings). Attempting to render all 3 equal size buildings at once takes hours with Open GL, and then cannot be completed in LW.

I still haven’t any ideas on the banding issue other than it’s isolated to the Dual Xeon. AFA bios settings, I am willing to try but am not terribly experienced with system settings.

To complete this project I will try to render each building alone, then reassemble in Photoshop, or will isolate & turn off distant roof tile surfaces.
Thanks again for your thoughtful comments.
Scott

Re: 'Banded' Photo Rendering

Anonymous — Mon, 25 Jul 2005 16:26:40 GMT

Karl wrote:
Interesting, Scott. There's lots of polygons in them there tiles! ...

Not being able to view the model in 3D blocks all kinds of other options. For example, Artlantis R deals with large polygon count models very well, by all accounts. While you could download the demo version (30 day trial) to check it out ... you have to export to ATL from the 3D window ... and you can't display in the 3D window...

You used to be able to set up a camera view looking away from the model and then export that empty view to Artlantis. I assume that this is still possible with Artlantis R.

Re: 'Banded' Photo Rendering

Karl Ottenstein — Tue, 26 Jul 2005 04:08:25 GMT

Millard wrote:
You used to be able to set up a camera view looking away from the model and then export that empty view to Artlantis. I assume that this is still possible with Artlantis R.

Thanks for the reminder, Millard! I'm always forgetting that old trick! A friend sent me this quote this morning, which seems remarkably appropriate: "Right now I'm having amnesia and deja-vu at the same time. I think I've forgotten this before." -- Steven Wright

Scott: Do you have shadow casting turned off for the tile objects? Should help some. (If you are using the SkyObject and SunObject with multiple light sources, the total shadow computation would be enormous if the tiles are casting shadows.) And, of course, the obvious as a workaround: are the tiles really necessary at the zoom/scale of the final image? Would a bump mapped tile image work just as well at your output scale?

Karl

Re: 'Banded' Photo Rendering

Dwight — Tue, 26 Jul 2005 04:14:08 GMT

I have done renderings with buzzillions of Onyx Tree leaves and no trouble.

My suspicion is that there is a problem with the machine or the RAM.

Re: 'Banded' Photo Rendering

Scott Bulmer — Tue, 26 Jul 2005 15:16:59 GMT

To summarize:
1) LW Banding is isolated to Dual Xeon. DX performs normal for all other tasks. Recommendation: Run some form of further diagnostics to be determined.
2) LW will not render excessive Roof Surfacer Italian tiles on either machine. Too many polygons. Recommendation: Punt!
3) Shadow casting was off for all Italian tiles, 3D was set to simple. Lighting sources are sun & sky objects w/ shadow casting by lamp setting.
4) For LW, Karl’s recommendation to change to bump mapped tiles for the distant buildings and Roof Surfacer on for the closest building to the camera. Will try.
5) For Artlantis, Millard’s/Karl’s recommendation to download trial version & export empty view of model (in theory the Open GL shaded view should render much faster looking away from the model, and Artlantis allegedly can handle more polygons than LW).
Thank you all again for your valuable time and insights.
Scott

Re: 'Banded' Photo Rendering

Dwight — Tue, 26 Jul 2005 15:21:03 GMT

how many light sources in your sunandskyobjects?

did you reduce them?

Re: 'Banded' Photo Rendering

Scott Bulmer — Tue, 26 Jul 2005 16:48:59 GMT

Dwight wrote:

how many light sources in your sunandskyobjects?

Interesting question:
15 in the sun, 46 is greyed out in sky with 5 latitude, 15 longitude, shadow quality is 5 and soft (but shadow casting setting for tiles is off).
I haven't tried a reduction of light sources as yet. Could you please recommend a realistic setting at your convenience?

Re: 'Banded' Photo Rendering

Dwight — Tue, 26 Jul 2005 20:09:40 GMT

4-6 suns - for soft light 45 divergence

lat 3 long 6 on the skyobject

what you using?

or give up and use the built-in sun with weak intensity and lots of ambient

Re: 'Banded' Photo Rendering

Scott Bulmer — Wed, 27 Jul 2005 04:37:29 GMT

Dwight wrote:
give up and use the built-in sun with weak intensity and lots of ambient

Per your suggestion above, LW is able to render on the Dual Xeon (see attached). However, it still produces a banding pattern when the sun/sky objects are used, even when reducing the light sources as recommended. This Dual Xeon does not like this model when rendering in LW using the sun/sky objects.