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OldMan
11-21-2008, 03:28 AM
Hi.

I am working on an application where I need a render target with at least 14 bits of precision on 3 channels. Th e logical choice would be RGBA16. But I know GF 6 and 7 series at least do not support those natively, they convert those trough 8 bit per channel. And that is supported by this ..

http://developer.nvidia.com/object/nv_ogl_texture_formats.html


Unfortunately that is quite old, lacks DX10 class hardware and I could not find anything similar for ATI cards.

Is there any hardware that support that natively or should I have to render to 32 bit floating target? If possible I would like to avoid that since those target textures are to be returned to system memory to be analysed by a CPU level algorithm (on such high volume that wasting bandwidth would not be good practice).

Also any different ideas on how to achieve that precision in a render target would be appreciated.

Thanks for any help.

PkK
11-21-2008, 04:22 AM
Looking at the hardware documentation of the latest intel graphics chips it seems they support such a render target (and a RGB16 render target).
However it is not exposed in the Linux drivers (they convert to RGBA8, too) and Intel's Windows drivers tend to be worse than their Linux drivers.

Philipp

IneQuation.pl
11-21-2008, 06:15 AM
Floating point render target is the obvious answer, then.

OldMan
11-21-2008, 06:40 AM
The problem is FP16 has only 10 bit precision while FP32 doubles the bandwidth usage. This is for medical application so DEMANDING a specific hardware would not be a problem, as long as that hardware existed :P

Groovounet
11-21-2008, 07:26 AM
Why not using a GeForce 8 then ? Oo

zeoverlord
11-21-2008, 09:04 AM
Well if bandwidth is the problem and hardware is not, then just double the hardware bandwidth through SLI.

The problem with the intel chips is that they are not high performance parts, i would rather use a good quad Nvidia SLI setup with the latest hardware, that way you would probably not have to drop down to the "cpu level algorithm" as you could just use cuda for that.

Warshade
11-21-2008, 09:05 AM
With FBO and GLSL you can attach RGBA8 to slot 0 and another RGBA8 to slot 1. You'll have to pack/unpack though.

OldMan
11-24-2008, 02:38 AM
That is what i waned to know. GF8 do have NATIVE support for it?


The double target idea is a nice one. Think will try it. Thanks.

Nicolai de Haan
11-25-2008, 04:57 AM
Last I checked, GF8 and later do support FBO rendering to RGB16/RGBA16 (but LUMINANCE16 was unsupported).