Large render

[Peter Milner]

Here is virtually the same scene rendered at two different sizes.

The first is to go in a brochure (5080 x 1878 pixels) and the second is to go on the side of a large lorry (10808 x 5404 pixels).

As you can see, the large rendering is virtually black and even if I increase the brightness to maximum in the nXt image editor, it makes very little difference.

[Roy Hirshkowitz]

If you don't mind-- try comparing a few pixel values to help see if the problem is in the image or the rendering.  Use the cursor and the status bar to compare-- I'm most interested in the Lum field.

[Roy Hirshkowitz]

Actually-- I can see a problem already.   There's a field towards the bottom of the info box which is mislabeled (I need to fix this)-- it contains the average luminance value of the image.  It's very different (and incorrect) in the dark image.  This is calculated in the image editor where I'm guessing the problem is happening-- although a bad pixel in the rendering could be causing this as well.

I probably need to get a hold of this image if possible.  Will likely require dropbox or eq. since it's large.

[Peter Milner]

I'll send it by wetransfer.

Can you remind me of your email address.

[Roy Hirshkowitz]

You can use [e-mail]

[Peter Milner]

Just to let you know, it's not specific to this rendering. It's happened on another one as well which also has a minimum luminance of 0.0001.

[Roy Hirshkowitz]

I'm not sure I can debug this one-- it brought my machine to its knees yesterday.

It's not the minimum luminance field that's bad-- that one is no problem.  The line above the max, which is mislabeled but is supposed to be the average luminance, is the one that's busted.  That's calculated by the Image Editor and is clearly having some indeterminate problem in this image.

*********

Have you tried running the thing interactively on your main box? It's possible this is a problem with the image editor-- running it in AutoCAD might allow you to save a png.

[Peter Milner]

It's way to big to run on my local machine. It took 52.5 hours to render on the farm with 80 cores. I ran 2000 passes split into 20 tasks and then added them together in the image editor.

[Roy Hirshkowitz]

It still might be worth running it for a few passes and see if the display looks normal-- that would confirm for me that the problem is in the image editor.

*****

I can take another look, probably early next week, but I can't promise anything.  I'll need to run it under the scope and disable large portions of memory allocation code just so I can work with the thing.  Altering it this much may make it impossible to find the problem.

[Peter Milner]

Everything renders fine on my local machine and I can save it as a tiff or png without any problems.

But if I save it as an nXt and open it in the image editor, I get the same problem.

[Roy Hirshkowitz]

Thanks-- that's helpful (and as expected).  I'll take a look at it in a couple of days and see what I can find.

[Roy Hirshkowitz]

Still unable to debug this one-- it's just too large for my system.  I can't even get it to load into the image editor-- several hours later it's still trying.

If you have something smaller exhibiting the same problem let me know-- I may be able to run it.  Otherwise I may be stuck.  It may be possible to make the farm save a png directly-- that might work.

[Peter Milner]

That's strange. It only takes about 30 seconds to load on mine, but it does take up 10Gb of RAM.