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Poser Technical F.A.Q (Last Updated: 2024 Nov 13 12:50 am)

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Subject: HDRI explained continued...


prixat ( ) posted Mon, 10 January 2005 at 4:33 PM · edited Fri, 29 November 2024 at 5:09 AM

Operaguy The output (often called probes) from HDRshop and other such progs. are not really for use as stills. They attempt to contain the extra intensity information that real world lighting has. This can not be re-produced on a monitor or photo. Once you have got hold of your probes (stop sniggering at the back) It still takes a 3D program to interpret them. At its simplest a program could just interpret the 20 brightest points of the probe and create a light set mapped on a sphere. With more sophistication you can use the information in the probe to control the percentage intensity of individual lights in your light set. So having set up your HDRI environment you animate in the normal way. Apologies if this was too simplistic, someone may find it useful!

regards
prixat


prixat ( ) posted Mon, 10 January 2005 at 4:48 PM

If you wanted to create a probe, one way would be to use a digital camera and a mirrored sphere. In the location of your choice you take a series of shots of the sphere at different exposures. It is these very specific set of tifs that HDRshop requires to produce a single probe. When you look at a picture of the sun on your monitor there is no danger of burning your retina as in the real world! If you make a HDRI probe of the sun (it will contain that intensity) then use the HDRviewer there is still no way your monitor could harm your retina! Thats what is meant by "not reproducible on a photo or monitor".

regards
prixat


maxxxmodelz ( ) posted Mon, 10 January 2005 at 4:52 PM

It should be pointed out, there's a big difference between low dyanmic range lighting and true HDRI, which is calculated using GI light "physics" in advanced renderers. The lighting you generate from the lightgen utility utilizes standard 3D lights and approximates the intensity and colors to match the probe. it's a way to "fake" HDRI in applications that do not support rendering with light probes natively. In applications that do support HDRI, no actual direct lights need to be added to the scene when using HDRI (unless you want to add them). All the light in the scene would come from the probe itself.


Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.


prixat ( ) posted Mon, 10 January 2005 at 5:00 PM

Interestingly, PoseRay has real radiosity but has to fake HDRI!

regards
prixat


operaguy ( ) posted Mon, 10 January 2005 at 5:37 PM

max, thanks for the HDRI-for-poets level explanation! well, I am starting to catch on. Very fascinating. Since Poser is an app that does NOT have native or 'true' HDRI lighting, and leaving aside for the moment the option of rendering your poser scene and animation in an app that does, I wonder if the game is worth the candle. Several products already exist that fake GI, I've acquired two of them, and they do produce superior results under certain circumstances. For an animator, however, unless you are big-studio'ed up, it's far too costly in render time, of course. There is no free lunch. Since you can get HDRShop1 for free for non-comercial, and stewer's python script, I'll try it some time soon. ::::: Opera :::::


maxxxmodelz ( ) posted Mon, 10 January 2005 at 7:00 PM

Yeah, even big studios don't often use actual GI/HDRI calculations in their renders. For years, the meathod of choice has always been to fake the look using standard lighting. It's faster, and can be made to fake the look of actual GI quite well (if you know how to set up the light rigs). Nowadays, there are renderers out there for higher end programs that make true GI and HDRI rendering "production-capable", but it's still much slower per frame than using standard lights, and also... HDRI rendering for animation requires your GI sampling to be set quite high to avoid artifacting and flickering. HDRI lighting is still unpredictable at lower settings for animation, even in the best renderers. I've used Vray for 3dsmax (which boasts some of the fastest GI calculations in the biz), and still it was up to 3 times slower than using a standard light dome to fake GI, and when I tried HDRI lighting on anything less than very high settings, I got problems with flickering and surface issues. Looked really GREAT though at high settings, but the frames were just taking too long to render.


Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.


maxxxmodelz ( ) posted Mon, 10 January 2005 at 7:15 PM

"Interestingly, PoseRay has real radiosity but has to fake HDRI!" That's actually not surprising. 3dsMax 5 had real radiosity calculations as well, but no direct support for HDRI using it's standard scanline renderer without a plugin. Of course, versions 6 and up do support it directly through the integrated Mental Ray engine.


Tools :  3dsmax 2015, Daz Studio 4.6, PoserPro 2012, Blender v2.74

System: Pentium QuadCore i7, under Win 8, GeForce GTX 780 / 2GB GPU.


operaguy ( ) posted Mon, 10 January 2005 at 7:26 PM

i suspected as much about the flicker, that's why I asked about it explicitly in the prior thread. Thanks max. I am learning to get the most out of three white lights and the shaders in the material room. ::::: Opera :::::


Iefke ( ) posted Wed, 12 January 2005 at 12:53 PM

Attached Link: http://megapov.inetart.net/

Using Poseray you can get real HDRI lighting around a Poser scene for free by rendering with Megapov instead of Povray. Megapov is an unofficial version of Povray with extra features like HDRI. In short: - create your Poserscene, lights are not important, save it. - export to .obj - start Poseray and import your scene, ignore the lights. - save as .pov scene - open .pov scene with Megapov, delete lights that remain and replace with a HDRI light (examples are included with Megapov). - render ! Povray scenes give nice results with Megapov and HDRI. I wasn't able to get the same 'stunning' results with a Poser scene. I suspect that the small scale of Poser scenes has something to do with it. (even Poser 5's Firefly has problems with it). I have to experiment some more with scaling the poser scene 100 times or so. Time, time, time ... ;=) Yvo


prixat ( ) posted Wed, 12 January 2005 at 7:29 PM

Do you think the HDRI feature will be in the next release of POVRay?

regards
prixat


Iefke ( ) posted Fri, 14 January 2005 at 11:27 AM

I don't know prixat. I believe POVray is completely rewritten at the moment. In the past features of Megapov have been included with POVray, so I expect HDRI in POVray sooner or later. Yvo


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