What I don't like about iRay

hphoenix

TheKD said:

mjc1016 said:

TheKD said:

I find I understand iray seetings fairly easily, but I am coming from a houdini backround, so I am very used to PBR. It was a pain in the ass to learn though for the first time, same with the light settings, learning to use the camera as you would a real camera, setting ISO and Fstop, and shutter speed.

The thing that really bugs me, is that iray seems to be poorly optimized for texture maps or something. I started out testing stuff, rendering one full figure with clothes and hair fit in my 2Gb Vram just fine, but two will not. Somehow I can play fallout 4 at ultra settings, with lots of 4k texture mods, CBBE people running around no problem, never dipping below 50 FPS expcept when it gets really crouded. But two genesis 3 girls, and it chokes. 

I think that vendors should start offering more texture resolution setting option, with the push toward GPU rendering. Sure, end user can do it, but the vendor already knows where they put the maps, and we have to hunt for them. CPU iray is flat out garbage, iray made to sell high end nvidia cards, period. In mantra(A CPU PBR) I can render two full genesis 3 girls way faster than iray can render one with CPU.

The speed of iray when it works got me interested, plus it's a lot easier than having to pose > export > locate all the maps that don't export properly with the export map option(pisses me off to no end that bug), import, set up lighting > build new shaders, plug in the maps > render. I was really interested in Iray until I actually stopped testing it, and started trying to make art with it.

I am running a test now, had to export, locate all maps, now in the process of halfing them, see if that helps it fit in the Vram. 

1.  Games, especially hi-res replacement textures make use of mipmapped/compressed textures.  Art rendering is an etriely different beast.  You DO NOT want to compromise testures...so yes, they will take up much more video memory.  Plus in a game there is a lot more reuse of the textures and a lot more swapping them in and out.  It is not a flaw nor is it something that the vendors should have to worry about.  2 GB is reather low for art rendering...4 GB is really the bottom end.

2.  It is not a bug that not all maps are loaded/'exported properly'.  It is a limitation of the format used. If it is an obj export, that is very limited and very few maps will actually be used (diffuse, bump and transparency (and that one may/maynot be 'right') are the 'standards specified' ones).

3. Shader/material set up should never be considered when looking at whether or not the export 'worked'.  No two renderers speak the same materials language, so saying that you have to set up materials again when using a different renderer, when using something other than the one they are native to, is not a bug/fault/problem...it's just a fact of life. There are open/'common formats that can be used instead of the proprietary shading languages that are currently used.  They just aren't...it is not something that Daz can do much about, they didn't create the problem and don't make any of the renderers used.

1) I disagree, to a certain point. You do not really need a 4k map for rendering a midground or background person/clothing/whatever, unless you are kinda crazy like me and like to render at insane resloutions a lot. I guess I am just sick and tired of it all really. I have been trying to find a great pipeline to make my art for years, always hitting brick walls everywhere lol. I wish I was rich enough to afford the kinds of machines I see some people using, might make things a lot easier. I don't have a crappy PC, I don't think, but certainly not one of those 16 core beasts with 10 980Ti cards haha.

2)Is there any one format I can choose to get it to spit all the maps out, or even a combo? As it stands now, I export as obj, and mostly I get diffuse maps, some transmaps, rarely get bump or spec though, and have to go hunting for them. I would love just an export all texture used button, that would be helpful.

3) I understand that about renders, used cycles(in fact, if I recall correctly, you wrote a very helpful script that exported figures to blender, thanks, I used that at one time), maya mray, maya vray, houdini mantra now, just getting into iray. I wish I was really good at coding, and could write my own export/import stuff for say houdini. My big probelm with houdini is getting skin looking anything near realistic. I saw Iray renders, and was like woah. Now I am hitting the vram brick wall, and the brick wall of no dynamic strand hair. I can't win, maybe I should just give up this realism kick and just do stylized :D 

I've put together a set of scripts for DAZ that do the resizing (using ImageMagick, free).....you just select the items in the scene, run the script, and presto!  All the images used by that item (but NOT any child items unless you multi-selected them too) are resized in half and quarter sizes (medium and small).  The original size images are untouched.  And the other script allows you to select items and switch all the images used on those items to use the full, medium, or small sized textures.

I'm still polishing up the UI parts of them.  And there is an issue with ImageMagick resizing greyscale PNGs with an alpha layer embedded that I'm trying to find a solution to.  But the rest works just fine.

Going from full size to half-size saved me about 450MB of VRAM.  Of course, it will vary GREATLY from scene to scene.  But using it on figures is where the majority of the savings will come in, as the images are usually 4k x 4k, and unless you are rendering at enormous sizes or doing extreme closeups, some or all of those are going to be way larger than needed to still maintain sub-pixel details.

(as an interesting aside, the Iray compression thresholds have a big effect here.  At the default settings, almost ALL images get compressed, and use the high-compression settings.  But once some images start falling below that into the low compression or no compression ranges, you may not see much benefit in the resizing (compression is like that, trying to compress a small item even smaller often ends up using MORE space) so you will need to adjust some stuff manually.  Also, optimizing for memory or using high compression on the images do both slow down rendering in Iray.....If you have plenty of VRAM left in the scene, up your compression thresholds and let all the images load full size.  You will see a speed up, though it may not be very noticeable if you have a really fast GPU rig.)

 

ETA:  The scene the above was referenced from contained a set (four walls with details and windows), various props (some simple, some complex, some instanced), and one G2F figure with clothes and hair.  There were both 3DL surfaces and Iray surfaces/shaders.  Total VRAM used with DS and the scene loaded was just above 1200MB.  Max used while Iray was running was 3080MB with full sized images, 2600MB with half-resolution images.