memory cost of 3 bw masks vs 1 RGB mask

gregsandor · May 20, 2010, 06:58:37 PM

Hey guys -- I have a lot of large black and white masks for a scene. If I combine three at a time, as RGB channels, then split them via functions once in TG, would that reduce the memory consumption or is it the same cost?

gregsandor · May 23, 2010, 11:51:38 AM

Anyone?

Tangled-Universe · May 23, 2010, 02:15:42 PM

I don't know, why don't you try it yourself?

Oshyan · May 27, 2010, 03:09:39 AM

I would think it should be the same memory cost. TG2 needs to store everything in memory at full bit depth, no compression, and all channels. So whether it's 1 image with 3 channels or 3 with 1 each, it should be similar. There should only be a minimal difference due to file container overhead.

- Oshyan

gregsandor · May 27, 2010, 03:48:48 AM

Excellent news. Thanks, Oshyan.

gregsandor · June 03, 2010, 06:45:38 PM

Hang on, if I currently have 3 images, that's 9 channels. If I combine them it reduces to 3 channels, so the overall cost is less. Right?

Currently reading http://forums.planetside.co.uk/index.php?topic=2519.0 as I work on this. I've combined my masks for a test and will post updates.

Oshyan · June 04, 2010, 02:11:27 AM

I was assuming you were using 1 channel images. But come to think of it, I'm not certain TG2 supports them, at least not for all formats. Maybe TIF, SGI, and/or EXR.

- Oshyan

gregsandor · June 04, 2010, 02:26:04 AM

How do you reduce an image to a single channel? When I split to RGB then save one, on opening it seems to have 3.

Meanwhile, can anyone help me figure out how to seperate a RGB image into the separate channels. I've tried constant Colour Red ---> Subtract Colour ---> Blend by Shader but get weird results. Is there a function to do this better?

I think I've found it: Red to scalar, Green to scalar, Blue to scalar seems to work so far. What does scalar mean?

Tangled-Universe · June 04, 2010, 03:43:16 AM

Here's some info about scalars:

http://en.wikipedia.org/wiki/Scalar_(mathematics)
http://en.wikipedia.org/wiki/Scalar_multiplication

gregsandor · June 04, 2010, 04:02:33 AM

Thanks. I've converted some of my masks and updated the tgd. Running my first test render now. If it doesn't crash I'll consider it a success. Meanwhile I'll read up on the links you posted.

gregsandor · June 04, 2010, 04:03:28 AM

Damn. Back to the drawing board.