[prodviz]

Hi all,

setting the image output to exr and 'output image depth' to 16BPP renders out a 32 bit image.

How do we go about rendering out a Half Float files?

cheers,

Steve

[prodviz]

I noticed on the recent Maxell webinar that there was no half float option for exr's in SoftImage.

Is this the case for Maya?

[prodviz]

The 'Compression' button is greyed out.

Is there a way/option to select this?

cheers,

Steve

[Mihnea Balta]

How did you determine the EXR is full-float even though you set 16-bit in the render options? We've just tested now and it seems to render to half-float correctly.

The compression button is greyed out because we're not using it. :) Maya does not give plug-ins an "official" way to customize output formats and change what the compression button does (and when it's enabled or not). We edit the list of supported formats with a hack. On the other hand, Maxwell does not support specifying the compression for EXR output yet, so there's no point for adding a compression button in the plug-in.

[prodviz]

Hi Mihnea,

Thanks for the info.

The top RGB layer has a range of:

-6.5 to +1EVs

and some of the light layers go to:

-15 EVs.

Do half float images hold this sort of range?
Great, if so.

cheers,

Steve

[Mihnea Balta]

Half floats can store numeric values between -65504 and 65504 (although the precision is lousy when the numbers are large, e.g. 64500 is "rounded" to 64512). I'm not sure how the EV range is computed for images (and which software you've used for it), but if it's just a log scale, a range of 15 would mean a difference of 32000 units, which can be represented in half float (although again, with bad precision).

You can use an image viewer with support for EXR (such as djv_view) to check the actual depth of an output file.

[prodviz]

I used Photoshop for the EV info.
(When I import images into Photoshop, 1 EV seems to equate to 1 stop.)

Cheers for the info on djv_view.

I've opened the file in djv_view and the info says F32.

Where would I see if the layers of the exr are in 16bits?

[raduc]

I used Photoshop for the EV info.
(When I import images into Photoshop, 1 EV seems to equate to 1 stop.)

Cheers for the info on djv_view.

I've opened the file in djv_view and the info says F32.

Where would I see if the layers of the exr are in 16bits?

If djv_view info says the channels are F32 then it's not half float, have you set the Output Image Depth to 16 bpp in the Maxwell Render tab in Maya ?

[prodviz]

cool, cheers.

I think I slipped up here. Looks like I missed the 'Output Image Depth' option.

This, set at 16BPP and rendered, shows as F16 in djv.

Still shows as 32bit in photoshop though.

Cheers again for your help.

Steve.