'Banded' Photo Rendering

[Scott Bulmer]

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.

[Scott Bulmer]

The Open GL shaded image used prior to photo rendering.

[__archiben]

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

[Scott Bulmer]

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

[Karl Ottenstein]

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

[Scott Bulmer]

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?

[Scott Bulmer]

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.

[Scott Bulmer]

Part 2.

[Karl Ottenstein]

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

[Scott Bulmer]

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