Crop pixel problems

[AJ Jefferies]

Hello,

I'm trying to render a fairly hefty scene in sections using crop - something I've done many times before. Firstly, when I send the scene to our rendering Xeons I get a timeout after 600 minutes - yet I've set the 'wait for Max to render' value to 70000 minutes.

To get round this for now I'm sending smaller crops which are rendering fine - apart from each crop seems to be a slightly different size to the original render I'm overlaying them onto.

Hopefully these two images can explain a little clearer.





In the first image the fine lines on the right are aligned but the highlight on the left does not. In the second image the highlight on the left is aligned but the lines are not.

This isn't the first time I've experienced this problem & I wondered if anyone could shed any light on it?

[vlado]

There was a thread somewhere on the 3dsmax forum how to set the timeout to more than 600 minutes, maybe you can still find it.

Otherwise, you can try the stripe rendering with backburner.

Best regards,
Vlado

[AJ Jefferies]

Cool - any word/idea on why the crops don't seem to line up with a full render from the same camera...?

We get it a lot with architectural work - the bricks from a crop or region fix not quite lining up with the original image.

[Clifton Santiago]

Don't render using crop. Use Split Scanlines in Backburner instead, as Vlado suggested. This will eliminate the problem.

[AJ Jefferies]

So, for example, if I need to render a 300x300 pixel area from a 8'000x8'000 render - I would need to render the entire image again - but in strips?

[Clifton Santiago]

You don't have to, I'm just saying it will fix your alignment problem.

But I don't think in terms of region/crop rendering anymore. I will usually re-render entire large renders using render strips in backburner overnight on my render farm.

If I have to change just one thing, like the color of a brick wall, I would render an alpha channel of the brick wall and merge it into the image to comp out the brick and change the color manually. Or I might re-render just the brick wall, with all other objects as matte shadow so as to match the lighting, and then just drop the new brick wall into the old rendered image. You shouldn't have any alignment problems with either method, because in terms of pixels you are rendering the "whole" image, but only calculating the parts that need to be changed.